Understanding Functional Neurological Disorder: Recent Insights and Diagnostic Challenges

Functional neurological disorder (FND), formerly called conversion disorder, is a condition characterized by neurological symptoms that lack an identifiable organic purpose. These signs, which can consist of motor, sensory, or cognitive disturbances, are not deliberately produced and often vary in severity. Its diagnosis is predicated on clinical evaluation and the exclusion of other medical or psychiatric situations. Its treatment typically involves a multidisciplinary technique addressing each of the neurological symptoms and underlying psychological factors via a mixture of medical management, psychotherapy, and supportive interventions. Recent advances in neuroimaging and a deeper exploration of its epidemiology, pathophysiology, and clinical presentation have shed new light on this disorder. This paper synthesizes the current knowledge on FND, focusing on its epidemiology and underlying mechanisms, neuroimaging insights, and the differentiation of FND from feigning or malingering. This review highlights the phenotypic heterogeneity of FND and the diagnostic challenges it presents. It also discusses the significant role of neuroimaging in unraveling the complex neural underpinnings of FND and its potential in predicting treatment response. This paper underscores the importance of a nuanced understanding of FND in informing clinical practice and guiding future research. With advancements in neuroimaging techniques and growing recognition of the disorder's multifaceted nature, the paper suggests a promising trajectory toward more effective, personalized treatment strategies and a better overall understanding of the disorder.

How Positive Are Conversion Disorder Diagnoses?: Patterns of Referral to a Functional Neurology Clinic

ABSTRACT

The Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) diagnostic criteria for conversion disorder have replaced the criterion of evidence of a "psychogenic" etiology with a criterion that patients must be "positively" diagnosed on the basis of their neurological assessment. We retrospectively studied referrals to a specialist functional neurology clinic to see how commonly the new criteria were met since DSM-5's introduction. Positive signs were reported in a quarter of referrals (26.5%), which was associated with diagnosticians' confidence (p = 0.001) and with the clinic confirming the diagnosis (p = 0.01). Our clinic found positive signs in 28.6% of the referrals. In 13 (13.3%) patients, the new criterion was not met. In conclusion, positive signs are diagnostically helpful but are only reported in a minority of assessments. A significant group of those currently believed to have conversion disorder would not meet the revised diagnostic criteria based on this.

Management of functional communication, swallowing, cough and related disorders: consensus recommendations for speech and language therapy

Communication problems (eg, dysphonia, dysfluency and language and articulation disorders), swallowing disorders (dysphagia and globus), cough and upper airway symptoms, resulting from functional neurological disorder (FND), are commonly encountered by speech and language professionals. However, there are few descriptions in the literature of the most effective practical management approaches. This consensus document aims to provide recommendations for assessment and intervention that are relevant to both adults and young people. An international panel of speech and language professionals with expertise in FND were approached to take part. Participants responded individually by email to a set of key questions regarding best practice for assessment and interventions. Next, a video conference was held in which participants discussed and debated the answers to these key questions, aiming to achieve consensus on each issue. Drafts of the collated consensus recommendations were circulated until consensus was achieved. FND should be diagnosed on the basis of positive clinical features. Speech and language therapy for FND should address illness beliefs, self-directed attention and abnormal movement patterns through a process of education, symptomatic treatment and cognitive behavioural therapy within a supportive therapeutic environment. We provide specific examples of these strategies for different symptoms. Speech and language professionals have a key role in the management of people with communication and related symptoms of FND. It is intended that these expert recommendations serve as both a practical toolkit and a starting point for further research into evidence-based treatments.

The auditory startle response in relation to outcome in functional movement disorders

BACKGROUND

The auditory startle reflex (ASR) is enlarged in patients with functional movement disorders (FMD).

OBJECTIVES

To study whether the ASR relates to symptom reduction in FMD patients, who participated in a placebo controlled double blind treatment trial with Botulinum Neurotoxin (BoNT).

METHODS

Response to treatment in the BoNT study was assessed using the Clinical Global Impression - Improvement scale (CGI-I). The electromyography (EMG) muscle activity of 7 muscles following 110 dB tones was measured in 14 FMD patients before and after one-year treatment and compared to 11 matched controls. The early and a late (behaviorally affected) component of the ASR and the sympathetic skin response (SSR) were assessed.

RESULTS

10 of 14 patients (71.4%) showed symptom improvement, which was believed to be mainly caused by placebo effects. The early total response probability of the ASR at baseline tended to be larger in patients compared to controls (p = 0.08), but normalized at follow-up (p = 0.84). The late total response probability was larger in patients vs. controls at baseline (p < 0.05), a trend that still was present at follow-up (p = 0.08). The SSR was higher in patients vs. controls at baseline (p < 0.01), and normalized at follow-up (p = 0.71).

CONCLUSIONS

On a group level 71.4% of the patients showed clinical symptom improvement after treatment. The early part of the ASR, most likely reflecting anxiety and hyperarousal, normalized in line with the clinical improvement. Interestingly, the augmented late component of the ASR remained enlarged suggesting persistent altered behavioral processing in functional patients despite motor improvement.

Effects of TPH2 gene variation and childhood trauma on the clinical and circuit-level phenotype of functional movement disorders

BACKGROUND

Functional movement disorders (FMDs), part of the wide spectrum of functional neurological disorders (conversion disorders), are common and often associated with a poor prognosis. Nevertheless, little is known about their neurobiological underpinnings, particularly with regard to the contribution of genetic factors. Because FMD and stress-related disorders share a common core of biobehavioural manifestations, we investigated whether variants in stress-related genes also contributed, directly and interactively with childhood trauma, to the clinical and circuit-level phenotypes of FMD.

METHODS

Sixty-nine patients with a 'clinically defined' diagnosis of FMD were genotyped for 18 single-nucleotide polymorphisms (SNPs) from 14 candidate genes. FMD clinical characteristics, psychiatric comorbidity and symptomatology, and childhood trauma exposure were assessed. Resting-state functional connectivity data were obtained in a subgroup of 38 patients with FMD and 38 age-matched and sex-matched healthy controls. Amygdala-frontal connectivity was analysed using a whole-brain seed-based approach.

RESULTS

Among the SNPs analysed, a tryptophan hydroxylase 2 (TPH2) gene polymorphism-G703T-significantly predicted clinical and neurocircuitry manifestations of FMD. Relative to GG homozygotes, T carriers were characterised by earlier FMD age of onset and decreased connectivity between the right amygdala and the middle frontal gyrus. Furthermore, the TPH2 genotype showed a significant interaction with childhood trauma in predicting worse symptom severity.

CONCLUSIONS

This is, to our knowledge, the first study showing that the TPH2 genotype may modulate FMD both directly and interactively with childhood trauma. Because both this polymorphism and early-life stress alter serotonin levels, our findings support a potential molecular mechanism modulating FMD phenotype.

Functional gait disorders, clinical phenomenology, and classification

BACKGROUND

Functional gait disorders (FGDs) are relatively common in patients presenting for evaluation of a functional movement disorder (FMD). The diagnosis and classification of FGDs is complex because patients may have a primary FGD or a FMD interfering with gait.

METHODS

We performed a detailed evaluation of clinical information and video recordings of gait in patients diagnosed with FMDs.

RESULTS

We studied a total of 153 patients with FMDs, 68% females, with a mean age at onset of 36.4 years. A primary FGD was observed in 39.2% of patients; among these patients, 13 (8.5%) had an isolated FGD (a gait disorder without other FMDs). FMDs presented in 34% of patients with otherwise normal gait. Tremor was the most common FMD appearing during gait, but dystonia was the most common FMD interfering with gait. Patients with FGD had a higher frequency of slow-hesitant gait, astasia-abasia, bouncing, wide-based gait and scissoring compared with patients with FMDs occurring during gait. Bouncing gait with knee buckling was more frequently observed in patients with isolated FGD (P = 0.017). Patients with FGDs had a trend for higher frequency of wheelchair dependency (P = 0.073) than those with FMDs interfering with gait.

CONCLUSIONS

Abnormal gait may be observed as a primary FGD or in patients with other FMDs appearing during gait; both conditions are common and may cause disability.

Prevalence of restless legs syndrome in functional movement disorders: a case-control study from the Czech Republic

OBJECTIVES

The prevalence of restless legs syndrome (RLS) in functional movement disorders (FMD) is not known. Patients with FMD often present with multiple motor and sensory symptoms. Some of these symptoms might be due to comorbid RLS. Therefore, our objective was to evaluate possible association between FMD and RLS.

DESIGN

Case-control study.

SETTING

Movement Disorders Center, 1st Faculty of Medicine and General University Hospital in Prague, Czech Republic.

PARTICIPANTS

96 consecutive patients with clinically established FMD (80 females, mean age (SD) 45.0 (13) years), and 76 matched controls.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome measure was prevalence of RLS based on updated International RLS Study Group criteria. Secondary outcome measures included prevalence of periodic limb movements (PLM) using actigraphy; pain, motor and sensory symptoms in lower limbs; organic comorbidities and medication affecting RLS.

RESULTS

RLS criteria were fulfilled in 43.8% of patients (95% CI 34 to 54) and in 7.9% of controls (95% CI 3 to 17, p<0.00001). Both RLS and PLM indices (PLMi) ≥22.5/hour were found in 21.2% of patients with FMD and 2.6% of controls. Patients with FMD with RLS had a higher mean PLMi (p<0.001) and a higher proportion of PLMi ≥22.5/hour (p<0.01) than RLS-negative patients. Patients with RLS had higher prevalence of pain and sensory symptoms in lower limbs, no difference was found in medication and prevalence of organic comorbidities in patients with FMD with and without RLS.

CONCLUSIONS

We found an increased prevalence of RLS in patients with FMD. Clinical diagnosis of RLS was supported by actigraphic measurement of clinically relevant PLM in a significant proportion of patients with FMD. Although functional motor and sensory symptoms may mimic RLS, RLS may be unrecognised in patients with FMD. This finding may have clinical implications in management of FMD, and it raises the possibility of common pathophysiological mechanisms of FMD and RLS/PLM.

Characteristics of Children Hospitalized for Psychogenic Nonepileptic Seizures Due to Conversion Disorder Versus Epilepsy

OBJECTIVES

Psychogenic nonepileptic seizures (PNES) are a manifestation of conversion disorder among children but can be difficult to distinguish from epilepsy. We sought to identify characteristics that differentiate children with PNES from those with epilepsy.

METHODS

We conducted a retrospective cohort study of children admitted with epilepsy or PNES to 45 children's hospitals from 2004 to 2014. Children with PNES (n = 399) versus those with epilepsy (n = 13 241) were compared on demographic and clinical characteristics, testing, treatment, and health care use. Hierarchical multivariable logistic regression was used to identify characteristics associated with PNES diagnosis.

RESULTS

Children with PNES were more likely to be female (adjusted odds ratio [aOR] 2.3; 95% confidence interval [CI] 1.8-3.0), older (aOR 3.8; 95% CI 2.7-5.3 for 14-16 years old), African American (aOR 2.0; 95% CI 1.5-2.7), and have diagnosis codes for psychiatric disorders (aOR 7.1; 95% CI 5.6-9.1) and pain (aOR 2.6; 95% CI 1.9-3.4). They were also more likely to be admitted in the fall (aOR 2.0; 95% CI 1.4-2.8) or spring (aOR 1.9; 95% CI 1.4-2.6) versus summer. Total adjusted hospitalization costs were greater for children with epilepsy ($4724, 95% CI $4413-$5057 vs $5326, 95% CI $5259-$5393; P = .001); length of stay was similar.

CONCLUSIONS

Demographic and clinical characteristics differed among children with PNES versus those with epilepsy, including significantly increased odds of psychiatric and pain diagnoses among children with PNES. To better inform treatment and prognostication for children with PNES, research is needed to understand reasons for these differences, seasonal admission patterns, and the relationship between PNES and other psychiatric disorders.

Conversion, Factitious Disorder and Malingering: A Distinct Pattern or a Continuum?

This chapter is aimed at highlighting the recent findings concerning physiopathology, diagnosis, and management of conversion, factitious disorder, and malingering. Conversion disorder is the unintentional production of neurological symptom, whereas malingering and factitious disorder represent the voluntary production of symptoms with internal or external incentives. They have a close history and this has been frequently confounded. Practitioners are often confronted to medically unexplained symptoms; they represent almost 30% of neurologist's consultation. The first challenge is to detect them, and recent studies have confirmed the importance of "positive" clinical bedside signs based on incoherence and discordance, such as the Hoover's sign for the diagnosis of conversion disorder. Functional neuroimaging has allowed a better understanding of the pathophysiology, and highlighted abnormal cerebral activation patterns in conversion disorder in relation to motor, emotional, and limbic networks, different from feigners. This supports the theory evoked by Charcot of a "psychodynamic lesion," which is also reflected by the new term introduced in the DSM-5: functional neurological disorder. Multidisciplinary therapy is recommended with behavioral cognitive therapy, antidepressant to treat frequent comorbid anxiety or depression, and physiotherapy. Factitious disorder and malingering should be clearly delineated from conversion disorder. Factitious disorder should be considered as a mental illness and more research on its physiopathology and treatment is needed, when malingering is a non-medical condition encountered in medico-legal cases.

Impaired awareness of motor intention in functional neurological disorder: implications for voluntary and functional movement

BACKGROUND

Functional neurological disorders (FNDs), also known as conversion disorder, are unexplained neurological symptoms unrelated to a neurological cause. The disorder is common, yet poorly understood. The symptoms are experienced as involuntary but have similarities to voluntary processes. Here we studied intention awareness in FND.

METHOD

A total of 26 FND patients and 25 healthy volunteers participated in this functional magnetic resonance study using Libet's clock.

RESULTS

FND is characterized by delayed awareness of the intention to move relative to the movement itself. The reporting of intention was more precise, suggesting that these findings are reliable and unrelated to non-specific attentional deficits. That these findings were more prominent with aberrant positive functional movement symptoms rather than negative symptoms may be relevant to impairments in timing for an inhibitory veto process. Attention towards intention relative to movement was associated with lower right inferior parietal cortex activity in FND, a region early in the processing of intention. During rest, aberrant functional connectivity was observed with the right inferior parietal cortex and other motor intention regions.

CONCLUSIONS

The results converge with observations of low inferior parietal activity comparing involuntary with voluntary movement in FND, emphasizing core deficiencies in intention. Heightened precision of this impaired intention is consistent with Bayesian theories of impaired top-down priors that might influence the sense of involuntariness. A primary impairment in voluntary motor intention at an early processing stage might explain clinical observations of slowed effortful voluntary movement, heightened self-directed attention and underlie functional movements. These findings further suggest novel therapeutic targets.

Neurobiologic theories of functional neurologic disorders

Although neurobiologic theories to explain functional neurologic symptoms have a long history, a relative lack of interest in the 20th century left them far behind neurobiologic understanding of other illness. Here we review the proposals for neurobiologic mechanisms of functional neurologic symptoms that have been made over time and consider how they might inform our diagnostic and treatment methods, and how they integrate with psychologic formulations of functional symptoms. Modern approaches map on to recent developments in theoretic models of brain function, and suggest a key role for processes affecting attention, beliefs/expectations, and a resultant impairment of sense of agency.

Diagnosis of Laryngopharyngeal Reflux Among Globus Patients

OBJECTIVES: Laryngopharyngeal reflux (LPR) is suggested as one of the most common etiologic factors of globus; currently, however, only a few tools are available to carry out effective diagnosis of LPR in clinics. The goal of this study was to assess the validity of reflux finding score (RFS), reflux symptom index (RSI), and symptom checklist-90-revision (SCL-90-R) as diagnostic methods for LPR.

STUDY DESIGN AND SETTING: We selected 57 globus patients who were divided into test and control groups according to the results of 24-hour double-probe ambulatory pH monitoring. RFS, RSI, and SCL-90-R were then compared between the 2 groups, and the logical products of the 3 tests were also compared.

RESULTS: RFS and RSI showed low specificity and there was no significant difference between the test and control groups. However, SCL-90-R revealed significantly high scores in the control group. The logical product of combining positive RFS and negative SCL-90-R was significantly different between the groups.

CONCLUSION: RFS and RSI are less valid as diagnostic tools for LPR when used independently. Patients with LPR are found to exhibit weaker psychological symptoms than non-LPR patients.

EBM rating: B-2b

Somatic symptoms scale: Psychometric properties in clinical and normal sample

OBJECTIVE

To develop a Somatic Symptoms Scale based on the criteria of standard symptoms, and to examine its psychometric properties through exploratory factor analysis.

METHODS

The study was conducted from January, 2010 to May, 2011 at two teaching hospitals in Lahore city and comprised female adolescents with somatic symptoms diagnosed by a psychiatrist, and an equal number of adolescents with minor physical disability. All patients were recruited from psychiatric out-door units of different hospitals. All subjects were unmarried. Translated Urdu version of the Somatic Symptoms Scale was administered to each participant individually. They were instructed to read the scale carefully and select the response that was most appropriate. The assessment procedure was done in a separate room on the hospital premises.

RESULTS

There were 150 female adolescents with somatic symptoms and equal number of females with minor disability. The overall mean age was 15.50+/-1.67 years (range: 14-17 years).Exploratory factor analysis showed that the two groups were significantly different on conversion motor symptoms (p<0.001), conversion sensory symptoms (p<0.001), pain symptoms (p<0.001), hypochondriacal symptoms (p<0.001) and body dysmorphic symptoms (p<0.001).

CONCLUSIONS

The Somatic Symptoms Scale was found to be a valid and reliable measure which can be used as screening instrument for non-clinical population and as a diagnostic measure in clinical population.

Emotion-motion interactions in conversion disorder: an FMRI study

Objectives

To evaluate the neural correlates of implicit processing of negative emotions in motor conversion disorder (CD) patients.

Methods

An event related fMRI task was completed by 12 motor CD patients and 14 matched healthy controls using standardised stimuli of faces with fearful and sad emotional expressions in comparison to faces with neutral expressions. Temporal changes in the sensitivity to stimuli were also modelled and tested in the two groups.

Results

We found increased amygdala activation to negative emotions in CD compared to healthy controls in region of interest analyses, which persisted over time consistent with previous findings using emotional paradigms. Furthermore during whole brain analyses we found significantly increased activation in CD patients in areas involved in the ‘freeze response’ to fear (periaqueductal grey matter), and areas involved in self-awareness and motor control (cingulate gyrus and supplementary motor area).

Conclusions

In contrast to healthy controls, CD patients exhibited increased response amplitude to fearful stimuli over time, suggesting abnormal emotional regulation (failure of habituation / sensitization). Patients with CD also activated midbrain and frontal structures that could reflect an abnormal behavioral-motor response to negative including threatening stimuli. This suggests a mechanism linking emotions to motor dysfunction in CD.

I wept for four years and when I stopped I was blind

The conversion phenomena of hysteria were the subject of intense study in the late nineteenth and early twentieth centuries, after which work on the subject went into decline. The patients are still with us, however, and I cite an epidemic of hysterical blindness among Cambodian refugees living in the U.S. as a poignant example. Since the advent of brain imaging technology, conversion hysteria has been receiving renewed attention. In this paper, I suggest that examining the ideas about hysteria from the past, especially those of Charcot and Janet are fertile areas of study, including the illness and its relation to hypnosis, shock, suggestion, and dissociation theory. I also address the role of the imaginary and the imagination in the illness and critique the implicit dualist model used in most brain imaging studies that distorts the integration of psyche and soma. I summon Merleau-Ponty's body-subject, infant research on intersubjectivity, and Vittorio Gallese's "embodied simulation" as possible windows onto the problem of hysterical conversion, and finally I suggest that along with imaging studies, more dynamic narrative strategies should be used if we hope to understand the metamorphoses, mimesis, and powerful emotions that all play a part in this mysterious disease.

[Neurology of hysteria (conversion disorder)]

Hysteria has served as an important driving force in the development of both neurology and psychiatry. Jean Martin Charcot's devotion to mesmerism for treating hysterical patients evoked the invention of psychoanalysis by Sigmund Freud. Meanwhile, Joseph Babinski took over the challenge to discriminate between organic and hysterical patients from Charcot and found Babinski's sign, the greatest milestone in modern neurological symptomatology. Nowadays, the usage of the term hysteria is avoided. However, new terms and new classifications are complicated and inconsistent between the two representative taxonomies, the DSM-IV and ICD-10. In the ICD-10, even the alternative term conversion disorder, which was becoming familiar to neurologists, has also disappeared as a group name. The diagnosis of hysteria remains important in clinical neurology. Extensive exclusive diagnoses and over investigation, including various imaging studies, should be avoided because they may prolong the disease course and fix their symptoms. Psychological reasons that seem to explain the conversion are not considered reliable. Positive neurological signs suggesting nonorganic etiologies are the most reliable measures for diagnosing hysteria, as Babinski first argued. Hysterical paresis has several characteristics, such as giving-way weakness or peculiar distributions of weakness. Signs to uncover nonorganic paresis utilizing synergy include Hoover's test and the Sonoo abductor test.

Distinct modulation of event-related potentials during motor preparation in patients with motor conversion disorder

Objective

Conversion paresis patients and healthy people feigning weakness both exhibit weak voluntary movement without detectable neuropathology. Uniquely, conversion patients lack a sense of conscious awareness of the origin of their impairment. We investigated whether conversion paresis patients show distinct electroencephalographic (EEG) markers associated with their unconscious movement deficits.

Methods

Six unilateral upper limb conversion paresis patients, 12 feigning participants asked to mimic weakness and 12 control participants performed a precued reaction time task, requiring movements of either hand, depending on precue information. Performance measures (force, reaction and movement time), and event-related EEG potentials (ERP) were compared, between groups and across hands or hemisphere, using linear mixed models.

Results

Feigners generated the same inter-hand difference in reaction and movement time as expressed by patients, even though no specific targets were set nor feedback given on these measures. We found novel ERP signatures specific to patients. When the symptomatic hand was precued, the P3 ERP component accompanying the precue was dramatically larger in patients than in feigning participants. Additionally, in patients the earlier N1 ERP component was diminished when the precue signalled either the symptomatic or asymptomatic hand.

Conclusions

These results are consistent with previous suggestions that lack of awareness of the origin of their symptoms in conversion disorder patients may result from suppression of brain activity normally related to self-agency. In patients the diminished N1 to all precues is consistent with a generalised reduction in cognitive processing of movement-related precues. The P3 enhancement in patients is unlikely to simply reflect changes required for generation of impaired movements, because it was not seen in feigners showing the same behavioural deficits. Rather, this P3 enhancement in patients may represent a neural biomarker of unconscious processes, including additional emotional loading, related to active suppression of brain circuits involved in the attribution of self-agency.

Common imitators of epilepsy

Many episodic phenomena involving motor, sensory, autonomic, and behavioral functions may imitate epilepsy. The aim of this article is to focus on the various manifestations and the diagnostic and therapeutic challenges of the most common of these disorders, as well as their relationship to emotional aspects. Syncope is caused by reduced global cerebral perfusion. Convulsive movements are sometimes released from subcortical structures, but do not follow the characteristic sequence of tonic-clonic seizures, and postictal symptoms are minimal. Hyperventilation attacks are caused by the metabolic consequences of hypocapnia. Altered blood pH and cerebral vasoconstriction may cause a range of peripheral and central nervous system symptoms. Psychogenic non-epileptic seizures (PNES) are attacks of reduced self-control associated with various behavioral phenomena, usually beyond voluntary control. A detailed clinical history is the most important tool in the differential diagnosis. Various emotional factors may act as immediate triggers in reflex syncope and hyperventilation attacks, whereas in PNES, emotional traumas may be remote and suppressed. Patient education with appropriate explanation of the underlying mechanisms is a fundamental part of the management of these disorders.

One-stop evaluation of globus pharyngeus symptoms with transnasal esophagoscopy and swallowing function test

OBJECTIVE

To evaluate the feasibility of a one-stop assessment of patients complaining of globus sensation with transnasal esophagoscopy (TNE) and functional endoscopic evaluation of swallowing (FEES).

DESIGN

Prospective, nonrandomized, experimental investigation.

SETTING

Tertiary referral centre.

METHODS

Sixty-three consecutive patients complaining of a lump in the throat were evaluated by this combined approach.

MAIN OUTCOME MEASURES

The safety and feasibility of performing a one-stop TNE plus FEES were explored by subjective measurement of the patients' tolerance and satisfaction and comments from surgeons. The possible therapeutic effects were also assessed 2 months after the procedure.

RESULTS

All 63 patients completed the TNE and FEES without any complications. The average duration of the examination was 6.27 ± 2.52 (95% CI 5.63-6.91) minutes. The findings included arytenoid cyst, epiglottic cyst, vocal cord nodules, vocal cord palsy, esophageal reflux, and foveolar gland hyperplasia. Two patients (3.2%) demonstrated some degree of fluid penetration or aspiration. Nine specialists all scored highly on a visual analogue scale on the manipulation, visualization, and satisfaction of the TNE procedure (median  =  8 of 10). Patients also rated a low pain score (median  =  1 of 10) and a high satisfaction score (median  =  9 of 10).

CONCLUSION

The combined technique of TNE and FEES can be used safely as a one-stop examination tool for patients with globus pharyngeus symptoms.

[Assessment and treatment of conversion disorder: the most fascinating borderline of psychiatry and neurology]

Conversion disorder or functional neurological disorder is a neurological symptom complex originating from psychological factors, which manifests in voluntary motor and sensory functions or as unexplained epilepsy-like seizures. Until the 1980's the disorder was called hysterical neurosis. Later on, various general terms, such as unexplained somatic symptoms, pseudoneurological, somatoformic, psychogenic, or psychosomatic symptoms, have been applied. The latest phrase, functional neurological symptoms, emphasizes the change in the functioning of the nervous system rather than in its structure.

Chronic headaches and the neurobiology of somatization

Pain sensitivity is an adaptive process affected by expectation, mood, coping, operant conditioning, and the preconscious allocation of attention. Underlying mechanisms may include encoding of similar experiences (eg, depression, loss, pain-distress) in overlapping patterns of activation, failure of common regulatory mechanisms, direct top-down activation of the pain matrix, and changes in descending pain facilitatory and inhibitory tone. In theory, the combination of glial cell activation from psychological stress and neural firing from nociceptive input may be particularly likely to lead to pain sensitization and long-term structural changes in pain processing regions of the brain. In these ways, headaches in which chronicity, diffuseness, and distress seem better accounted for by psychological than by medical variables can be understood in neurobiological terms. This can allow psychological treatment of physical distress to be objective, nonthreatening, and relatively precise.

The involuntary nature of conversion disorder

BACKGROUND

What makes a movement feel voluntary, and what might make it feel involuntary? Motor conversion disorders are characterized by movement symptoms without a neurologic cause. Conversion movements use normal voluntary motor pathways, but the symptoms are paradoxically experienced as involuntary, or lacking in self-agency. Self-agency is the experience that one is the cause of one's own actions. The matched comparison between the prediction of the action consequences (feed-forward signal) and actual sensory feedback is believed to give rise to self-agency and has been in part associated with the right inferior parietal cortex. Using fMRI, we assessed the correlates of self-agency during conversion tremor.

METHODS

We used a within-subject fMRI block design to compare brain activity during conversion tremor and during voluntary mimicked tremor in 8 patients.

RESULTS

The random effects group analysis showed that conversion tremor compared with voluntary tremor had right temporoparietal junction (TPJ) hypoactivity (p < 0.05 family-wise error whole brain corrected) and lower functional connectivity between the right TPJ, sensorimotor regions (sensorimotor cortices and cerebellar vermis), and limbic regions (ventral anterior cingulate and right ventral striatum).

CONCLUSIONS

The right TPJ has been implicated as a general comparator of internal predictions with actual events. We propose that the right TPJ hypoactivity and lower TPJ and sensorimotor cortex interactions may reflect the lack of an appropriate sensory prediction signal. The lack of a match for the proprioceptive feedback would lead to the perception that the conversion movement is not self-generated.

Relationship between globus sensation and esophageal clearance

CONCLUSIONS

Videofluoroscopy (VF) in the prone position can diagnose a range of esophageal pathologies in all age groups. These correlate with globus sensation in younger and middle-aged patients in prone and supine positions. Abnormal esophageal clearance appears to be associated with globus sensation in young and middle-aged persons, but not in the elderly.

OBJECTIVES

To assess the correlation between globus sensation and abnormal esophageal clearance by VF in relation to body position and to investigate age-related abnormal esophageal clearance, as well as to confirm the utility of VF in diagnosing globus sensation in patients.

SUBJECTS AND METHODS

This was a prospective study. In 72 patients with globus sensation and 33 controls, esophageal clearance was assessed by VF in the upright, supine, and prone positions, and transfer of barium through the esophagus was classified as normal, esophageal retention, esophageal reflux, or pharyngeal reflux. The detection rate of abnormal esophageal clearance was compared among all subjects by age.

RESULTS

In the upright position, VF detected no significant differences in the detection rate of abnormal esophageal clearance and reflux between the patients with globus sensation and controls; however, the detection rate of abnormal esophageal clearance was significantly higher in the prone than in the upright and supine positions (p<0.001), and in all positions was significantly higher among globus sensation patients (p<0.05). In the supine and prone positions, there were significantly higher detection rates of abnormal esophageal clearance in patients than in controls in the young group (p<0.05). Additionally in the prone position, there was a significantly higher detection rate of abnormal esophageal clearance and reflux in patients than in controls in the middle-aged group (p<0.05). In all positions, no significant differences were observed in the detection rate of abnormal esophageal clearance and reflux in the patients and controls in the elderly group.

[Acute hemiplegia and hemianesthesia together with decreased tendon reflexes mimicking acute stroke representing a conversion disorder]

Acute hemiplegia and hemianesthesia is commonly caused by obstruction of major cortical arteries. Such a presentation secondary to a conversion reaction is very rare, especially in the pediatric age group. The authors report an adolescent presenting with acute complete left-sided hemiplegia and sensory loss together with decreased tendon reflexes mimicking an acute arterial stroke. Examination revealed Hoover's sign was present and the patient was oblivious to his stern neurological state. Movement of his paralytic limbs was observed during sleep. Cortical and spinal CT, cortical MRI, motor and somatosensory evoked potentials and a PET study were all normal. As such, the diagnosis of psychogenic hemiplegia was established, apparently within a period that the patient had experienced severe emotional stress while questioning his gender identity. After three days, the adolescent began to move the paralytic limbs along gradual resolution of sensory deficit, leading to complete clinical recovering within two months. Although extremely rare, a conversion reaction should be taken into account in children presenting with acute hemiplegia and anaesthesia, even accompanied with decreased tendon reflexes, when the patient is oblivious to his alleged grave state, and when clinical observations such as Hoover's sign remain intact, substantiated by normal extensive radiological and neurophysiological investigation. Intact motor evoked potentials serve as a key for the diagnosis of psychogenic hemiplegia and, should therefore be performed in suspected cases.

[Hysteria: an historical entity, a psychiatric condition or a neurological disease?]

It has been suggested that hysteria had waned and was an old-fashioned, stigmatizing and false concept, reflecting the incapacity of the medical community to establish a diagnosis in certain situations. Nowadays, however, those disturbances, now referred to as conversion or dissociative disorders, still remain a frequent and incapacitating condition that every clinician faces. These past decades, several studies have tried to better describe their clinical presentation and their neurobiological mechanisms, with the help of the development of new neuroimaging techniques. If the neurobiological correlates are now better understood, efficient treatments are still lacking and only a multidisciplinary (general practitioners, neurologists and psychiatrists) and individually-tailored therapy might be beneficial to the patients.

Impact of psychogenic movement disorders versus Parkinson's on disability, quality of life, and psychopathology

Patients with psychogenic movement disorders (PMD) often report severe impairment, yet the impact of PMD on disability and quality of life has not been examined. We compared 66 patients with PMD and 704 patients with Parkinson's disease (PD) on measures of disability (Older Americans Resources and Services Scale, OARS); quality of life (QOL; SF-12v2 Health Survey) and psychiatric symptomatology (Brief Symptom Inventory 18, BSI-18). On the total OARS, PMD and PD patients reported similar levels of disability (17.6 +/- 6.6, 19.8 +/- 10.9, P = 0.490 at "best" function and 24.1 +/- 11.2, 26.2 +/- 14.3, P = 0.497 at their "worst" function). PMD patients reported similar Physical Health QOL to PD patients (38.9 +/- 14.5, 39.8 +/- 11.6, P = 0.652) but worse mental health QOL (41.6 +/- 13.4 vs. 48.9 +/- 11.0, P < 0.001). On the BSI-18, PMD patients reported higher levels of distress on the Global Symptom Index (62.03 +/- 9.6 vs. 53.7 +/- 9.9, P < 0.001) and on Anxiety, Depression and Somatization subscales (PMD vs. PD scores: Anxiety 58.9 +/- 12.0 vs. 52.3 +/- 10.1, P < 0.001; Depression 58.8 +/- 11.9 vs. 51.3 +/- 10.3, P < 0.001; Somatization 60.5 +/- 11.0 vs. 54.7 +/- 8.7, P < 0.001). Thus, severity of disability reported by the PMD group was equal to that seen in a progressive neurodegenerative condition. Quality of life and mental health implications of PMD were also evident. PMD impacts several aspects of patient function and daily life.

[Evoked potentials and regional cerebral blood flow changes in conversion disorder: a case report and review]

Conversion disorder is defined as the presence of functional impairment in motor, sensory or neurovegetative systems which cannot be explained by a general medical condition. Although the diagnostic systems emphasize the absence of an organic basis for the dysfunction in conversion disorder, there has been a growing interest in the specific functional brain correlates of conversion symptoms in recent years, particularly by examining neuroimaging and neurophysiological measures. In this case report, regional cerebral blood flow changes and evoked potentials of a patient with conversion symptoms are presented. Somatosensory evoked potentials (SEP) of this patient with conversion disorder who had signs of movement disorder revealed that the latency to N20, P 25 waves were in normal limits while the amplitudes of the P25 and N33 components were extremely high (giant SEP). Regional cerebral blood flow assessment revealed hypoperfusion in the left parietal and temporal lobes of the brain. Three months after the first assessment, the control scans showed that the left parietal hypoperfusion disappeared while the left temporal hypoperfusion was still present. The following SEP evaluations which were repeated twice in three months intervals after the initial recordings, showed the persistence of the abnormalities in somatosensorial measures. The neurophysiological and neuroimaging findings in conversion disorder were reviewed and the results of the evaluations of this case were discussed in this article.

Paul Blocq and (psychogenic) astasia abasia

The Greek term astasia-abasia literally translates to mean inability to stand and to walk. Although today we would classify the syndrome as a conversion disorder, it was considered a separate disease by Paul Blocq (1860-1896), who described this phenomenon as the inability to maintain an upright posture, despite normal function of the legs in the bed. Paul Blocq's original 1888 articles on astasia abasia were read, partly translated from French to English, and the cases were summarized. A review of a selection of the literature following Blocq's description on astasia abasia was performed. Present day literature was consulted as well. Blocq reviewed what was known about astasia abasia in two papers. Although he was the first to use the combined term astasia abasia, he referred to similar descriptions of Charcot, Richer, Mitchell, Jaccoud, Roméi, and Erlenmeyer. Blocq's contribution was in compiling the experiences and observations of preeminent 19th century neurologists. He recognized that paralysis, jumping, fits, tremor, and bizarre behavior could all be associated with the syndrome. He distinguished the disorder from hysteria. Moreover, he presented a formal delineation of the gait disorder and provided a pathophysiologic concept. Prognosis was considered favorable. Paul Blocq directed attention to psychogenic gait disorders by publishing a small case series on astasia abasia. Today, these case descriptions would be likely considered cases of conversion or psychogenic gait disorder, with or without other conversion/psychogenic movement disorders.

How does our brain constitute defense mechanisms? First-person neuroscience and psychoanalysis

Current progress in the cognitive and affective neurosciences is constantly influencing the development of psychoanalytic theory and practice. However, despite the emerging dialogue between neuroscience and psychoanalysis, the neuronal processes underlying psychoanalytic constructs such as defense mechanisms remain unclear. One of the main problems in investigating the psychodynamic-neuronal relationship consists in systematically linking the individual contents of first-person subjective experience to third-person observation of neuronal states. We therefore introduced an appropriate methodological strategy, 'first-person neuroscience', which aims at developing methods for systematically linking first- and third-person data. The utility of first-person neuroscience can be demonstrated by the example of the defense mechanism of sensorimotor regression as paradigmatically observed in catatonia. Combined psychodynamic and imaging studies suggest that sensorimotor regression might be associated with dysfunction in the neural network including the orbitofrontal, the medial prefrontal and the premotor cortices. In general sensorimotor regression and other defense mechanisms are psychoanalytic constructs that are hypothesized to be complex emotional-cognitive constellations. In this paper we suggest that specific functional mechanisms which integrate neuronal activity across several brain regions (i.e. neuronal integration) are the physiological substrates of defense mechanisms. We conclude that first-person neuroscience could be an appropriate methodological strategy for opening the door to a better understanding of the neuronal processes of defense mechanisms and their modulation in psychoanalytic psychotherapy.

Clinical profile and outcome of conversion disorder in children in a tertiary hospital of north India

The clinical profile, commonly involved precipitating factors, comorbid conditions, treatment options and outcome of conversion disorder in 40 children in a tertiary level hospital in North India were studied, retrospectively. Majority of the patients were from rural India. Most common presenting symptom was psychogenic non-epileptic seizures; depression and anxiety were among the commonest comorbid conditions. Precipitating factors were predominantly scholastic problems. Treatment option included either psychotherapy only or combination of psychotherapy and pharmacotherapy. No significant difference was found in terms of outcome between the in-patient and out-patient treatment groups. This observation could be cost effective for developing countries like India, where the resources are very limited.

Increased self-monitoring during imagined movements in conversion paralysis

Conversion paralysis is characterized by a loss of voluntary motor functioning without an organic cause. Despite its prevalence among neurological outpatients, little is known about the neurobiological basis of this motor dysfunction. We have examined whether the motor dysfunction in conversion paralysis can be linked to inhibition of the motor system, or rather to enhanced self-monitoring during motor behavior. We measured behavioral and cerebral responses (with fMRI) in eight conversion paralysis patients with a lateralized paresis of the arm as they were engaged in imagined actions of the affected and unaffected hand. We used a within-subjects design to compare cerebral activity during imagined movements of the affected and the unaffected hand. Motor imagery of the affected hand and the unaffected hand recruited comparable cerebral resources in the motor system, and generated equal behavioral performance. However, motor imagery of the affected limb recruited additional cerebral resources in the ventromedial prefrontal cortex and superior temporal cortex. These activation differences were caused by a failure to de-activate these regions during movement imagery of the affected hand. These findings lend support to the hypothesis that conversion paralysis is associated with heightened self-monitoring during actions with the affected arm.

Conversion disorder presenting as hemiplegia and hemianesthesia with loss of neurologic reflexes: a case report

Conversion disorders can present with a variety of sensorimotor signs and symptoms. We present the case of a young woman who presented with sudden onset hemiplegia and hemianesthesia including unilateral loss of deep tendon reflexes, Babinski reflex, and loss of rectal tone with bladder incontinence. The loss of rectal tone, loss of deep tendon reflexes, and a flaccid Babinski reflex are unusual signs in conversion disorders. A thorough medical workup including x-rays, CT scans, and magnetic resonance imaging revealed no organic causes for the neurologic deficits. Before the onset of symptoms, the patient was emotionally upset during an argument, which may have provided the psychologic stressor necessary for a conversion disorder. The young woman gradually regained full neurologic function over the next 14 hours. Conversion disorders should be considered when the neurologic findings do not correspond to known anatomic or physiologic pathways, although a thorough medical investigation must be performed to search for organic causes.

Abnormal brain activation during movement observation in patients with conversion paralysis

Dissociative paralysis in conversion disorders has variably been attributed to a lack of movement initiation or an inhibition of movement. While psychodynamic theory suggests altered movement conceptualization, brain activation associated with observation and replication of movements has so far not been assessed neurobiologically. Here, we measured brain activation by functional magnetic resonance imaging during observation and subsequent imitative execution of movements in four patients with dissociative hand paralysis. Compared to healthy controls conversion disorder patients showed decreased activation of cortical hand areas during movement observation. This effect was specific to the side of their dissociative paralysis. No brain activation compatible with movement inhibition was observed. These findings indicate that in dissociative paralysis, there is not only derangement of movement initiation but already of movement conceptualization. This raises the possibility that strategies targeted at reestablishing appropriate movement conceptualization may contribute to the therapy of dissociative paralysis.

Evolution of the human fear-circuitry and acute sociogenic pseudoneurological symptoms: the Neolithic balanced-polymorphism hypothesis

In light of the increasing threat of large-scale massacres such as terrorism against non-combatants (civilians), more attention is warranted not only to posttraumatic stress disorder (PTSD) but also to acute sociogenic pseudoneurological ("conversion") symptoms, especially epidemic sociogenic symptoms. We posit that conversion disorders are etiologically related to specific evolutionary pressures (inescapable threats to life) in the late stage of the human environment of evolutionary adaptedness (EEA). Bracha et al. have recently argued that from the neuroevolutionary perspective, medically unexplained efferent vasovagal syncope and medically unexplained craniofacial musculoskeletal pain in young otherwise healthy individuals, may be taxonomized as stress and fear-circuitry disorders. In the present article, we extend neuroevolutionary perspectives to acute pseudoneurological sociogenic ("conversive") symptoms: psychogenic non-epileptic attacks ("pseudoseizures"), epidemic sociogenic disorders (DSM-IV-TR Epidemic "Hysteria"), conversive motor deficits (pseudo-paralysis and pseudo-cerebellar symptoms), and psychogenic blindness. We hypothesize that these perplexing pseudoneurological stress-triggered symptoms, which constitute psychopathology in extant humans, are traceable to allele-variant polymorphisms which spread during the Neolithic EEA. During Neolithic warfare, conversive symptoms may have increased the survival odds for some non-combatants by visually (i.e., "non-verbally") signaling to predatory conspecifics that one does not present a danger. This is consistent with the age and sex pattern of conversive disorders. Testable and falsifiable predictions are presented; e.g., at the genome-transcriptome interface, one of the major oligogenic loci involved in conversive spectrum disorders may carry a developmentally sensitive allele in a stable polymorphism (balanced polymorphism) in which the gene expression mechanism is gradually suppressed by pleiotropic androgens especially dehydroxyepiandrosterone sulfate (DHEA-S). Taxonomic implications for the much-needed rapprochement between the forthcoming Diagnostic and Statistical Manual for Mental Disorders, Fifth Edition (DSM-V) and the International Classification of Diseases (ICD) are discussed.

Hyperactive action monitoring during motor-initiation in conversion paralysis: an event-related potential study

Conversion paralysis (CP) is featured by a stress-induced tonic immobility. Although the neural correlates of this psychiatric condition remain largely unexplored, previous reports showed CP to be associated with anterior cingulate cortex (ACC) hyperactivity. We examined the ACC action monitoring function by recording event-related potentials (ERPs) when conversion patients (n = 6) with unilateral arm paresis made speeded responses with their affected and healthy arms on a flankers task. During this task, pre-response ACC action monitoring is reflected in the N2 ERP component, which is increased when incongruent stimuli lead to simultaneously activated competing response tendencies. The results showed that the N2 congruency effects were significantly increased for responses with affected hands compared to healthy hands. There were no such results for post-response monitoring. This study is the first to present electrophysiological correlates of action monitoring in CP and suggests ACC to be hyperactive when movements with affected arms are to be initiated.

Conversion disorder revisited

Conversion disorder is defined as a psychiatric illness whose symptoms or deficits, affecting voluntary motor or sensory function, cannot be explained by a neurological or general medical condition. Proposing a strategy in the search for the neural mechanisms underlying conversion disorder is a difficult task, partly because key features of the illness inherently lie on a continuum with other psychiatric disorders, such as depression and posttraumatic stress disorder. Recent brain imaging studies have revealed neural circuits involved in complex mental processes potentially related to conversion disorder. These studies are reviewed, together with neuroimaging work in conversion disorder and brain imaging studies that have enriched the conceptualization of memory and emotion in posttraumatic stress disorder and major depression. Analysis of this information from a symptom-based rather than a disease-category perspective leads to a brain-based cognitive model of conversion disorder. This model suggests that disconnected crosstalk between the individual subdivisions of the anterior cingulate and the prefrontal cortex might provide a neuroscientific basis for the psychodynamic dissociation hypothesis, traditionally the bedrock explanation of the relationship between internal conflict and physical deficit. The model also suggests novel research approaches, as well as opportunities for potential therapeutic interventions.

Hysterical conversion and brain function

Hysterical conversion disorders represent "functional" or unexplained neurological deficits such as paralysis or somatosensory losses that are not explained by organic lesions in the nervous system, but arise in the context of "psychogenic" stress or emotional conflicts. After more than a century of both clinical and theoretical interest, the exact nature of such emotional disorders responsible for hysterical symptoms, and their functional consequences on neural systems in the brain, still remain largely unknown. However, several recent studies have used functional brain imaging techniques (such as EEG, fMRI, PET, or SPECT) in the attempt to identify specific neural correlates associated with hysterical conversion symptoms. This article presents a general overview of these findings and of previous neuropsychologically based accounts of hysteria. Functional neuroimaging has revealed selective decreases in the activity of frontal and subcortical circuits involved in motor control during hysterical paralysis, decreases in somatosensory cortices during hysterical anesthesia, or decreases in visual cortex during hysterical blindness. Such changes are usually not accompanied by any significant changes in elementary stages of sensory or motor processing as measured by evoked potentials, although some changes in later stages of integration (such as P300 responses) have been reported. On the other hand, several neuroimaging results have shown increased activation in limbic regions, such as cingulate or orbitofrontal cortex during conversion symptoms affecting different sensory or motor modalities. Taken together, these data generally do not support previous proposals that hysteria might involve an exclusion of sensorimotor representations from awareness through attentional processes. They rather seem to point to a modulation of such representations by primary affective or stress-related factors, perhaps involving primitive reflexive mechanisms of protection and alertness that are partly independent of conscious control, and mediated by dynamic modulatory interactions between limbic and sensorimotor networks. A better understanding of the neuropsychobiological bases of hysterical conversion disorder might therefore be obtained by future imaging studies that compare different conversion symptoms and employ functional connectivity analyses. This should not only lead to improve clinical management of these patients, but also provide new insights on the brain mechanisms of self-awareness.

Salient findings: A potentially groundbreaking study on the neuroscience of hypnotizability, a critical review of hypnosis' efficacy, and the neurophysiology of conversion disorder

Three papers of special interest to researchers and clinicians alike have recently appeared in the general scientific and medical literatures. Two of these papers are original research studies that employ brain-imaging technologies, one using Magnetic Resonance Imaging (MRI), the other position emission tomography (PET). A third paper is a comprehensive review of the empirical findings on the clinical use of hypnosis in pediatric oncology. The research study using MRI technology is extraordinary, because it is the first to document differences in brain morphology between high hypnotizable and low hypnotizable individuals. Arguably, if its findings replicate, the study could be one of the most important developments in scientific hypnosis since the genesis of the Stanford scales 45 years ago. The PET study notes differences in brain activation during intentionally simulated and hypnotically experienced paralysis. The review article examines empirical work addressing the efficacy of hypnosis for procedural pain in pediatric oncology.

Healing the disembodied mind: contemporary models of conversion disorder

The cartesian separation of body and mind has underpinned medical conceptualization of conversion symptoms over the last four centuries. Eighteenth- and nineteenth-century models explained conversion symptoms on the basis of assumed organic lesions. Subsequent psychological formulations focused on mental phenomena, which were disembodied from underlying neurobiological processes. Contemporary theories challenge this disconnection. They place conversion symptoms within an evolutionary framework, arguing that mind is embodied in physical processes and confers significant survival advantage. Current neurobiological models explain conversation symptoms as part of the human emotional response to threat, reflecting either errors in how information about body state is processes and represented, or the motor component of an automatic emotional response. Patients with conversion disorder experience their body functions in a range of distressing and disturbing ways. In order to understand these phenomena, clinicians require conceptual models that expand the conventional dualistic mind-body paradigm, integrate multiple theoretical perspectives, and take into account environmental factors that shape evolutionary and individual development.

[Conversion disorders. From neurobiology to treatment]

The two international systems of diagnostic classification for psychiatric disorders, ICD-10 and DSM-IV, differentiate a variety of disorders or syndromes characterized by the common feature of the presence of physical symptoms without "organic correlate." Conversion disorders (DSM) or dissociative disorders (ICD) are historically related to the concept of hysteria. Like psychoanalytical theories, the DSM and ICD refer to a psychological conflict preceding the onset of physical symptoms, although in a purely descriptive manner. The etiology of these disorders is still not very well understood. This article summarizes present knowledge from clinical and epidemiological studies. Functional neuroimaging studies on conversion disorders, although still very rare, allow testing of hypotheses about neuronal mechanisms. Such studies question the traditional and often misinterpreted dichotomy between organic and psychogenic diseases.

Motor conversion disorders reviewed from a neuropsychiatric perspective

BACKGROUND

Conversion disorder is a somatoform disorder defined by the presence of pseudoneurologic symptoms relating to voluntary sensory or motor function. The correct diagnosis of conversion disorder presenting with motor symptoms is complicated by the lack of gold-standard diagnostic tests and the absence of a universally accepted set of positive diagnostic criteria. This article reviews the epidemiology, pathophysiology, presentation, differential diagnosis, treatment, and prognosis of motor conversion, placing emphasis on diagnostic validity, reliability, and utility, while evaluating the empirical evidence supporting diagnostic and treatment strategies.

DATA SOURCES AND STUDY SELECTION

Literature searches were carried out in PubMed using the keywords conversion disorder, motor conversion, dystonia, psychogenic, hysteria, somatization, motion disorder, movement disorder, and patho-physiology. Articles and book chapters in the author's personal collection were also utilized.

CONCLUSIONS

Advances in neuropsychiatric research are leading to significant improvements in the diagnosis and understanding of motor conversion disorders. Positive, objective, and quantitative diagnostic criteria show significant promise for enhancing diagnostic accuracy. Current pathophysiologic research has begun to provide mechanistic explanations for conversion symptoms, thus blurring the distinction between psychogenic and organic motor disorders.

Functional magnetic resonance imaging of the cerebral response to visual stimulation in medically unexplained visual loss

BACKGROUND

Medically unexplained visual loss occurs in 1 to 5% of patients attending ophthalmology clinics and for many it runs a chronic course. A psychogenic aetiology is presumed in such cases, but little is known about the underlying neural mechanisms. Recent studies have established the value of functional magnetic resonance imaging (fMRI) in understanding the mechanisms of unexplained motor and sensory symptoms. The purpose of this study was to use a similar strategy (fMRI) to evaluate the cerebral responses to visual stimulation in a group of patients with medically unexplained visual loss, in an attempt to determine the underlying neural mechanisms.

METHOD

Brain activation induced by periodic (monocular) 8 Hz visual stimulation was detected by fMRI in five patients with unexplained visual loss who fulfilled DSM-IV criteria for conversion disorder, and seven normal volunteers. Between-group differences in mean power of activation were estimated by fitting a one-way analysis of variance (ANOVA) model at each intracerebral voxel in standard space.

RESULTS

Compared with controls, patients showed reduced activation in visual cortices, but increased activation in left inferior frontal cortex, left insula-claustrum, bilateral striatum and thalami, left limbic structures, and left posterior cingulate cortex.

CONCLUSIONS

This preliminary study has identified novel neural correlates in patients with unexplained visual loss. The abnormal pattern of activation may reflect inhibition of primary visual cortex or a shift towards non-conscious (implicit) processing.

Functional neuroimaging of psychiatric disorders: exploring hidden behaviour

From the outset, people have had high expectations of functional neuroimaging. Many will have been disappointed. After roughly a decade of widespread use, even an enthusiastic advocate must be diffident about the impact of the two most frequently used techniques – positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) – upon clinical psychiatry. Perhaps this disappointment arises from an unrealistic expectation of what these techniques are able to tell us about the workings of the normal and the disordered brain. Anyone who hoped for intricate and unambiguous region-to-function mapping was always going to be disappointed. This expectation presupposes, among other things, a thorough understanding of the cognitive functions that are to be mapped onto the brain regions. This understanding, however, while developing, is still rudimentary. Mapping disorder along comparable lines is even more complex since it demands two levels of understanding. The first is of the healthy region-to-function mapping, the second of the disordered region-to-function mapping, which immediately demands a consideration of the nature of the function in the disordered state. After all, someone with schizophrenia, when confronted with a psychological task, might tackle it in a very different way, in terms of the cognitive strategies used, from a healthy person confronted with the same task. The observation that brain activity differs across the two individuals would only be interpretable insofar as one thoroughly understood the processes that each individual invoked in response to the task demands.