Symptomatic myoclonus

Case report: Unilateral GPi DBS in secondary myoclonus-dystonia syndrome after acute disseminated encephalomyelitis

Introduction

Deep brain stimulation (DBS) is an established and effective therapy for movement disorders. Here, we present a case of secondary myoclonus-dystonia syndrome following acute disseminated encephalomyelitis (ADEM) in childhood, which was alleviated by DBS. Using a patient-specific connectome analysis, we sought to characterise the fibres and circuits affected by stimulation.

Case report

We report a case of a 20-year-old man with progressive dystonia, myoclonic jerks, and impaired concentration following childhood ADEM. Motor assessments utilising the Unified Myoclonus Rating Scale (UMRS) and the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) revealed a greater improvement in dystonia compared to myoclonus following adjustments of DBS parameters. These adjustments were based on visualisation of electrode position and volume of tissue activated (VTA) 3 years after surgery. A patient-specific connectome analysis using the VTA as a region of interest revealed fibre tracts connecting to the cerebello-thalamo-cortical network and the superior frontal gyrus in addition to basal ganglia circuits as particularly effective.

Conclusion

Globus pallidus internus (GPi) DBS shows promise as a treatment for secondary myoclonus-dystonia syndromes. Personalised structural considerations, tailored to individual symptoms and clinical characteristics, can provide significant benefits. Patient-specific connectome analysis, specifically, offers insights into the structures involved and may enable a favourable treatment response.

Electrophysiological characteristics and anatomical differentiation of epileptic and non-epileptic myoclonus

Background

Electrophysiological techniques have been used for discriminating myoclonus from other hyperkinetic movement disorders and for classifying the myoclonus subtype. This study was carried out on patients with different subtypes of myoclonus to determine the electrophysiological characteristics and the anatomical classification of myoclonus of different etiologies. This study included 20 patients with different subtypes of myoclonus compared with 30 control participants. Electrophysiological study was carried out for all patients by somatosensory evoked potential (SSEP) and electroencephalography (EEG) while the control group underwent SSEP. SSEP was evaluated in patients and control groups by stimulation of right and left median nerves.

Results

This study included 50 cases with myoclonus of different causes with mean age of 39.3 ± 15.7 and consisted of 23 males and 27 females. Twenty-nine (58%) of the patients were epileptics, while 21 (42%) were non-epileptics. Cases were classified anatomically into ten cases with cortical myoclonus (20%), 12 cases with subcortical myoclonus (24%), and 28 cases with cortical–subcortical myoclonus (56%). There was a significant difference regarding the presence of EEG findings in epileptic myoclonic and non-epileptic myoclonic groups (P = 0.005). Also, there were significant differences regarding P24 amplitude, N33 amplitude, P24–N33 peak-to-peak complex amplitude regarding all types of myoclonus. Primary myoclonic epilepsy (PME) demonstrated significant giant response, juvenile myoclonic epilepsy (JME) demonstrated no enhancement compared to controls, while secondary myoclonus demonstrated lower giant response compared to PME.

Conclusion

Somatosensory evoked potential and electroencephalography are important for the diagnosis and anatomical sub-classification of myoclonus and so may help in decision-making regarding to the subsequent management.

Myoclonus- A Review

Myoclonus is a hyperkinetic movement disorder characterized by a sudden, brief, involuntary jerk. Positive myoclonus is caused by abrupt muscle contractions, while negative myoclonus by sudden cessation of ongoing muscular contractions. Myoclonus can be classified in various ways according to body distribution, relation to activity, neurophysiology, and etiology. The neurophysiological classification of myoclonus by means of electrophysiological tests is helpful in guiding the best therapeutic strategy. Given the diverse etiologies of myoclonus, a thorough history and detailed physical examination are key to the evaluation of myoclonus. These along with basic laboratory testing and neurophysiological studies help in narrowing down the clinical possibilities. Though symptomatic treatment is required in the majority of cases, treatment of the underlying etiology should be the primary aim whenever possible. Symptomatic treatment is often not satisfactory, and a combination of different drugs is often required to control the myoclonus. This review addresses the etiology, classification, clinical approach, and management of myoclonus.

Unusual Movement Disorders and Atypical Magnetic Resonance Imaging (MRI) Findings in Patients with West Nile Encephalitis: Case Reports of 2 Patients with Evidence of Clinical and Imaging Resolution with IVIG

BACKGROUND West Nile virus (WNv) is the leading cause of epidemic arbovirus encephalitis in the continental United States. Movement disorders (MDs) have been reported in 20% to 40% of patients with WNv and about 37% of patients with WNv encephalitis have changes on magnetic resonance imaging (MRI). We report 2 unusual cases of neuroinvasive WNv in patients with unusual MDs and unreported MRI findings. CASE REPORT In the first case, a 34-year-old man presented with a 1-week history of disinhibition, agitation, opsoclonus-myoclonus and ataxia syndrome (OMAS), tremor, and facial agnosia. Evaluation of his cerebrospinal fluid (CSF) revealed elevated immunoglobulin (Ig)M against WNv, a high level of protein (98 mg/dL), and an elevated white blood cell (WBC) count (134, 37% lymphocytes). An MRI of the brain showed an area of diffusion restriction in the splenium of the corpus callosum. The patient's MRI findings and OMA improved significantly after 2 treatments with i.v. IG (IVIG). In the second case, a 57-year-old woman presented with fever, headaches, psychosis, and ataxia; she was subsequently intubated for airway protection. Analysis of her CSF showed elevated IgM against WNv, a high level of protein (79 mg/dL), and elevated WBC count (106, 90% lymphocytes). One week after the onset of symptoms, the patient experienced facial dyskinesia. Later, she developed proximal bilateral lower extremity weakness. An MRI of her lumbar spine showed evidence of myeloradiculitis with contrast enhancement of the conus medullaris and ventral nerve roots. After a single treatment with IVIG, she had partial improvement in weakness. CONCLUSIONS MDs and changes on MRI have been reported in patients with neuroinvasive WNv disease. Our patient with OMAS also had transient splenial diffusion restriction on imaging, which, to the best of our knowledge, has not been previously reported with WNv infection. In both patients, treatment with IVIG resulted in improvement in symptoms.

Post-stroke Movement Disorders: Clinical Spectrum, Pathogenesis, and Management

Involuntary movements develop after 1-4% of strokes and they have been reported in patients with ischemic and hemorrhagic strokes affecting the basal ganglia, thalamus, and/or their connections. Hemichorea-hemiballism is the most common movement disorder following a stroke in adults while dystonia is most common in children. Tremor, myoclonus, asterixis, stereotypies, and vascular parkinsonism are other movement disorders seen following stroke. Some of them occur immediately after acute stroke, some can develop later, and others may have delayed onset progressive course. Proposed pathophysiological mechanisms include neuronal plasticity, functional diaschisis, and age-related differences in brain metabolism. There are no guidelines regarding the management of post-stroke movement disorders, mainly because of their heterogeneity.

Myoclonus-Ataxia Syndromes: A Diagnostic Approach

Background

A myriad of disorders combine myoclonus and ataxia. Most causes are genetic and an increasing number of genes are being associated with myoclonus-ataxia syndromes (MAS), due to recent advances in genetic techniques. A proper etiologic diagnosis of MAS is clinically relevant, given the consequences for genetic counseling, treatment, and prognosis.

Objectives

To review the causes of MAS and to propose a diagnostic algorithm.

Methods

A comprehensive and structured literature search following PRISMA criteria was conducted to identify those disorders that may combine myoclonus with ataxia.

Results

A total of 135 causes of combined myoclonus and ataxia were identified, of which 30 were charted as the main causes of MAS. These include four acquired entities: opsoclonus-myoclonus-ataxia syndrome, celiac disease, multiple system atrophy, and sporadic prion diseases. The distinction between progressive myoclonus epilepsy and progressive myoclonus ataxia poses one of the main diagnostic dilemmas.

Conclusions

Diagnostic algorithms for pediatric and adult patients, based on clinical manifestations including epilepsy, are proposed to guide the differential diagnosis and corresponding work-up of the most important and frequent causes of MAS. A list of genes associated with MAS to guide genetic testing strategies is provided. Priority should be given to diagnose or exclude acquired or treatable disorders.

Tremor and myoclonus

Tremor and myoclonus are two common hyperkinetic movement disorders. Tremor is characterized by rhythmic oscillatory movements while myoclonic jerks are usually arrhythmic. Tremor can be classified into subtypes including the most common types: essential, enhanced physiological, and parkinsonian tremor. Myoclonus classification is based on its anatomic origin: cortical, subcortical, spinal, and peripheral myoclonus. The clinical presentations are unfortunately not always classic and electrophysiologic investigations can be helpful in making a phenotypic diagnosis. Video-polymyography is the main technique to (sub)classify the involuntary movements. In myoclonus, advanced electrophysiologic testing, such as back-averaging, coherence analysis, somatosensory-evoked potentials, and the C-reflex can be of additional value. Recent developments in tremor point toward a role for intermuscular coherence analysis to differentiate between tremor subtypes. Classification of the movement disorder based on clinical and electrophysiologic features is important, as it enables the search for an etiological diagnosis and guides tailored treatment.

Stimulus Sensitive Foot Myoclonus: A Clue to Coeliac Disease

Background

Coeliac disease (CD) is an autoimmune enteropathy that may feature extraintestinal manifestations including cerebellar ataxia and myoclonus.

Methods and Results

A descriptive series of five patients with CD who presented with prominent stimulus-sensitive foot myoclonus.

Conclusions

Stimulus-sensitive foot myoclonus is a distinct clinical sign and may be a useful clue to the diagnosis of CD.

Progressive myoclonus ataxia: Time for a new definition?

BACKGROUND

The clinical demarcation of the syndrome progressive myoclonus ataxia is unclear, leading to a lack of recognition and difficult differentiation from other neurological syndromes.

OBJECTIVES

The objective of this study was to apply a refined definition of progressive myoclonus ataxia and describe the clinical characteristics in patients with progressive myoclonus ataxia and with isolated cortical myoclonus.

METHODS

A retro- and prospective analysis was performed in our tertiary referral center between 1994 and 2014. Inclusion criteria for progressive myoclonus ataxia patients were the presence of myoclonus and ataxia with or without infrequent (all types, treatment responsive) epileptic seizures. Inclusion criteria for isolated cortical myoclonus was the presence of isolated cortical myoclonus. Clinical and electrophysiological characteristics data were systematically scored.

RESULTS

A total of 14 progressive myoclonus ataxia patients (males, 7; females, 7), median age 14.5 years, and 8 isolated cortical myoclonus patients (males, 2; females, 6), median age 23.5 years, were identified. In 93% of the progressive myoclonus ataxia patients, ataxia started first (median 2 years) followed by myoclonus (4 years) and finally infrequent epilepsy (9.3 years), with a progressive course in 93%. In 64% of the progressive myoclonus ataxia patients, a genetic underlying etiology was identified, including 3 not earlier reported causative progressive myoclonus ataxia genes. In isolated cortical myoclonus patients, myoclonus started at (median) 12 years with progression over time in 63% and a single epileptic seizure in 1 patient. No genetic causes were identified.

CONCLUSION

Using a refined definition, we could create a rather homogenous progressive myoclonus ataxia group. Patients with isolated cortical myoclonus have a different course and do not appear to evolve in progressive myoclonus ataxia. The refined progressive myoclonus ataxia definition is a successful first step toward creating a separate syndrome for both clinical practice and future genetic research. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Neurophysiology of the "Celiac Brain": Disentangling Gut-Brain Connections

Celiac disease (CD) can be considered a complex multi-organ disorder with highly variable extra-intestinal, including neurological, involvement. Cerebellar ataxia, peripheral neuropathy, seizures, headache, cognitive impairment, and neuropsychiatric diseases are complications frequently reported. These manifestations may be present at the onset of the typical disease or become clinically evident during its course. However, CD subjects with subclinical neurological involvement have also been described, as well as patients with clear central and/or peripheral nervous system and intestinal histopathological disease features in the absence of typical CD manifestations. Based on these considerations, a sensitive and specific diagnostic method that is able to detect early disease process, progression, and complications is desirable. In this context, neurophysiological techniques play a crucial role in the non-invasive assessment of central nervous system (CNS) excitability and conductivity. Moreover, some of these tools are known for their valuable role in early diagnosis and follow-up of several neurological diseases or systemic disorders, such as CD with nervous system involvement, even at the subclinical level. This review provides an up-to-date summary of the neurophysiological basis of CD using electroencephalography (EEG), multimodal evoked potentials, and transcranial magnetic stimulation (TMS). The evidence examined here seems to converge on an overall profile of "hyperexcitable celiac brain," which partially recovers after institution of a gluten-free diet (GFD). The main translational correlate is that in case of subclinical neurological involvement or overt unexplained symptoms, neurophysiology could contribute to the diagnosis, assessment, and monitoring of a potentially underlying CD.

Neurophysiology of the "Celiac Brain": Disentangling Gut-Brain Connections

Celiac disease (CD) can be considered a complex multi-organ disorder with highly variable extra-intestinal, including neurological, involvement. Cerebellar ataxia, peripheral neuropathy, seizures, headache, cognitive impairment, and neuropsychiatric diseases are complications frequently reported. These manifestations may be present at the onset of the typical disease or become clinically evident during its course. However, CD subjects with subclinical neurological involvement have also been described, as well as patients with clear central and/or peripheral nervous system and intestinal histopathological disease features in the absence of typical CD manifestations. Based on these considerations, a sensitive and specific diagnostic method that is able to detect early disease process, progression, and complications is desirable. In this context, neurophysiological techniques play a crucial role in the non-invasive assessment of central nervous system (CNS) excitability and conductivity. Moreover, some of these tools are known for their valuable role in early diagnosis and follow-up of several neurological diseases or systemic disorders, such as CD with nervous system involvement, even at the subclinical level. This review provides an up-to-date summary of the neurophysiological basis of CD using electroencephalography (EEG), multimodal evoked potentials, and transcranial magnetic stimulation (TMS). The evidence examined here seems to converge on an overall profile of "hyperexcitable celiac brain," which partially recovers after institution of a gluten-free diet (GFD). The main translational correlate is that in case of subclinical neurological involvement or overt unexplained symptoms, neurophysiology could contribute to the diagnosis, assessment, and monitoring of a potentially underlying CD.

Myoclonic Disorders

Few movement disorders seem to make a straightforward approach to diagnosis and treatment more difficult and frustrating than myoclonus, due to its plethora of causes and its variable classifications. Nevertheless, in recent years, exciting advances have been made in the elucidation of the pathophysiology and genetic basis of many disorders presenting with myoclonus. Here, we provide a review of all of the important types of myoclonus encountered in pediatric and adult neurology, with an emphasis on the recent developments that have led to a deeper understanding of this intriguing phenomenon. An up-to-date list of the genetic basis of all major myoclonic disorders is presented. Randomized studies are scarce in myoclonus therapy, but helpful pragmatic approaches at diagnosis as well as treatment have been recently suggested.

Lance–Adams syndrome: A special case of a mother

Predicting the neurological outcome in survivors of cardiorespiratory arrest is difficult. A distinction has been made between acute and chronic posthypoxic myoclonus, called myoclonic status epilepticus and Lance–Adams syndrome (LAS), respectively, with the acute condition carrying a bad prognosis. Here, we report a case of a 37-year-old female who developed seizures after a successful cardiopulmonary resuscitation. The available literature on such cases is very rare and has generally mentioned a poor outcome. However, our patient was successfully managed and showed clinical features of LAS. Thus, making an early diagnosis and proper management of hypoxic brain insults is positively related to improving the patient's functional outcome.

Intermittent head drops: the differential spectrum

Intermittent Head Drops are episodic head flexion movements that can occur in a number of conditions. Typically, the term has mainly been related to epileptic episodes, but the spectrum of clinical conditions associated with this feature is wide-ranging even if never discussed in detail. By searching the electronic database, we may find that apart from the epileptic conditions, Intermittent Head Drops have been in fact reported in the setting of movement disorders, sleep disorders and even internal medicine disorders, such as Sandifer syndrome. We render an in-depth description of this characteristic phenomenon in different diseases, describing the clinical clues and neurophysiological patterns that may help the clinician to distinguish between the different settings of occurrence.

A novel diagnostic approach to patients with myoclonus

Myoclonus is a hyperkinetic movement disorder characterized by brief, involuntary muscular jerks. Recognition of myoclonus and determination of the underlying aetiology remains challenging given that both acquired and genetically determined disorders have varied manifestations. The diagnostic work-up in myoclonus is often time-consuming and costly, and a definitive diagnosis is reached in only a minority of patients. On the basis of a systematic literature review up to June 2015, we propose a novel diagnostic eight-step algorithm to help clinicians accurately, efficiently and cost-effectively diagnose myoclonus. The large number of genes implicated in myoclonus and the wide clinical variation of these genetic disorders emphasize the need for novel diagnostic techniques. Therefore, and for the first time, we incorporate next-generation sequencing (NGS) in a diagnostic algorithm for myoclonus. The initial step of the algorithm is to confirm whether the movement disorder phenotype is consistent with, myoclonus, and to define its anatomical subtype. The next steps are aimed at identification of both treatable acquired causes and those genetic causes of myoclonus that require a diagnostic approach other than NGS. Finally, other genetic diseases that could cause myoclonus can be investigated simultaneously by NGS techniques. To facilitate NGS diagnostics, we provide a comprehensive list of genes associated with myoclonus.

Clinical characteristics and etiology of transient myoclonic state in the elderly

OBJECTIVES

To clarify clinical picture of transient myoclonic state in elderly patients.

METHODS

The Aizawa Hospital database was searched to identify all patients with transient myoclonic state with or without asterixis between April 2006 and June 2013. Medical records, brain images and laboratory data including electroencephalograms and electromyograms were reviewed.

RESULTS

We found 26 patients: 10 women and 16 men, and their ages ranged from 56 to 96 years (79.7 ± 9.9 years, mean ± standard deviation). The affected sites of the myoclonic jerks were predominantly the lower face, neck and upper extremities. The myoclonus appeared at conscious resting condition, slightly exaggerated by posturing or action. Asterixis was observed in eight patients. Single myoclonic bursts were 1.70 ± 0.94 s long. The interval of myoclonic bursts was 4.47 ± 2.44 s. Single myoclonic bursts were composed of 9.5 ± 2.5 Hz myoclonic contractions, and single myoclonic contractions were 44.4 ± 12.3 ms in duration. Most of the patients suffered from chronic diseases, but they were basically independent in activity of daily living. Oral administration of clonazepam was effective.

CONCLUSIONS

Transient myoclonic state has relatively stereotyped features. The pathophysiology may include some metabolic abnormality on a background of age-related arteriosclerotic changes. Its prognosis is benign, and prompt oral administration of clonazepam abolishes it. Further investigations will be needed to clarify its cause and pathophysiology.

Corticostriatal interactions in the generation of tic-like behaviors after local striatal disinhibition

The pathophysiology of the tics that define Gilles de la Tourette syndrome (TS) is not well understood. Local disinhibition within the striatum has been hypothesized to play a pathogenic role. In support of this, experimental disinhibition by local antagonism of GABA-A receptors within the striatum produces tic-like phenomenology in monkey and rat. We replicated this effect in mice via local picrotoxin infusion into the dorsal striatum. Infusion of picrotoxin into sensorimotor cortex produced similar movements, accompanied by signs of behavioral activation; higher-dose picrotoxin in the cortex produced seizures. Striatal inhibition with local muscimol completely abolished tic-like movements after either striatal or cortical picrotoxin, confirming their dependence on the striatal circuitry; in contrast, cortical muscimol attenuated but did not abolish movements produced by striatal picrotoxin. Striatal glutamate blockade eliminated tic-like movements after striatal picrotoxin, indicating that glutamatergic afferents are critical for their generation. These studies replicate and extend previous work in monkey and rat, providing additional validation for the local disinhibition model of tic generation. Our results reveal a key role for corticostriatal glutamatergic afferents in the generation of tic-like movements in this model.

Opsoclonus-myoclonus syndrome attributable to West Nile encephalitis: a case report

Introduction

Opsoclonus-myoclonus syndrome is a very rare neurological disorder associated with some viral infections and exceptionally with the West Nile virus.

Case presentation

A 57-year-old Caucasian woman presented with fever, dizziness, balance difficulties, vomiting, dancing eye, altered speech, tremor, generalized myoclonus and failure to rise or stand. Our objective is to describe a patient with West Nile infection, which was identified both in her serum and cerebrospinal fluid and was associated with encephalitis and opsoclonus-myoclonus-ataxia syndrome.

Conclusions

Opsoclonus-myoclonus-ataxia syndrome continued for 4 weeks after onset, when she died. There was no evidence for any other etiology responsible for her opsoclonus-myoclonus syndrome. Her opsoclonus-myoclonus syndrome appeared associated with West Nile encephalitis and had an unfavorable evolution despite treatment.

Myoclonus in renal failure: Two cases of gabapentin toxicity

Gabapentin, an AED approved for the adjunctive treatment of partial seizures with/without secondary generalization and for the treatment of postherpetic neuralgia, is frequently used off-label for the treatment of both psychiatric and pain disorders. Since gabapentin is cleared solely by renal excretion, dosing requires consideration of the patient's renal function. Myoclonic activity may occur as a complication of gabapentin toxicity, especially with acute kidney injury or end-stage renal disease. We report 2 cases of myoclonic activity associated with gabapentin toxicity in the setting of renal disease which resolved with discontinuation of gabapentin and treatment with hemodialysis and peritoneal dialysis. As gabapentin has multiple indications and off-label uses, an understanding of myoclonus, neurotoxicity, and renal dosing is important to clinicians in multiple specialties.

Oculopalatal tremor: current concepts and new observations

PURPOSE OF REVIEW

Oculopalatal tremor (OPT) is an acquired disorder resulting from the interruption of a specific brainstem circuitry, the dentato-rubro-olivary pathway or Guillain-Mollaret triangle. The recent literature on OPT and olivary hypertrophy was reviewed with specific interest regarding causes, diagnostic procedures, physiopathology and therapies.

RECENT FINDINGS

OPT is associated with inferior olivary hypertrophy, and recent findings have provided a better understanding of its intimate mechanisms. A dual-mechanism model, combining an oscillator (inferior olive) and a modulator/amplifier (cerebellum), best explains the development of OPT. Electrotonic coupling and specific Ca channels contribute to oscillations of inferior olivary nucleus neurons in OPT. Improvement of visual symptoms can be achieved with oral gabapentin or memantine.

SUMMARY

Both the neuronal circuitry and the physiopathology of OPT are now better understood. This opens up an era of specific therapy for this rare cause of disabling oscillopsia.

Reversible myoclonus in a patient undergoing transcervical hysteroscopic surgery

We describe a 58-year-old woman who underwent hysteroscopic myomectomy to treat a large submucosal leiomyoma. A hypotonic glycine solution was instilled to distend the uterus. At one hour after the distending medium infusion started for hysteroscopic resection an electrolytic imbalance developed. One hour later myoclonus developed predominantly involving the bilateral sternocleidomastoidei and abdominal muscles. The patient was alert and cooperative; jerks were spontaneous and triggered by sensory stimuli. The electroencephalographic and brain computed tomography was normal. The clinical characteristics of her myoclonus resemble reticular reflex myoclonus, a form of subcortical myoclonus originating from the lower brainstem reticular formation. Given her severe hyponatremia we conjecture that she had symptomatic metabolic myoclonus caused by electrolytic disturbance. The case report we present underlines the need to detect in time and promptly treat neurological symptoms such as myoclonus suggesting resorption syndrome, an uncommon event complicating transcervical hysteroscopic surgery and urologic procedures.

Myoclonic disorders: a practical approach for diagnosis and treatment

Myoclonus is a sudden, brief, involuntary muscle jerk. It is caused by abrupt muscle contraction, in the case of positive myoclonus, or by sudden cessation of ongoing muscular activity, in the case of negative myoclonus (NM). Myoclonus may be classified in a number of ways, although classification based on the underlying physiology is the most useful from the therapeutic viewpoint. Given the large number of possible causes of myoclonus, it is essential to take a good history, to clinically characterize myoclonus and to look for additional findings on examination in order to limit the list of possible investigations. With regards to the history, the age of onset, the character of myoclonus, precipitating or alleviating factors, family history and associated symptoms and signs are important. On examination, it is important to see whether the myoclonus appears at rest, on keeping posture or during action, to note the distribution of jerks and to look for the stimulus sensitivity. Electrophysiological tests are very helpful in determining whether myoclonus is cortical, subcortical or spinal. A single pharmacological agent rarely control myoclonus and therefore polytherapy with a combination of drugs, often in large dosages, is usually needed. Generally, antiepileptic drugs such as valproate, levetiracetam and piracetam are effective in cortical myoclonus, but less effective in other forms of myoclonus. Clonazepam may be helpful with all types of myoclonus. Focal and segmental myoclonus, irrespective of its origin, may be treated with botulinum toxin injections, with variable success.

Transient myoclonic state with asterixis: primary motor cortex hyperexcitability is correlated with myoclonus

OBJECTIVE

To clarify the clinical features and mechanism of the transience of myoclonus in patients with a transient myoclonic state with asterixis (TMA).

METHODS

We investigated the clinical and eletrophysiological profiles of 6 patients with TMA (age: 84±3 years). During an asymptomatic period, somatosensory evoked potentials (SEPs) were recorded in all 6 patients and motor evoked potentials (MEPs) were examined in 1 patient. SEPs were recorded and jerk-locked back averaging (JLA) was performed in 2 patients while symptomatic. SEPs were also recorded from 8 aged control subjects (age: 68±5 years).

RESULTS

All TMA patients had mild chronic systemic diseases. During an asymptomatic period, SEP amplitudes were not significantly enlarged in comparison with control subjects, and MEPs were normal. Examination of 2 patients during symptomatic period indicated no enlargement of SEP amplitudes and JLA disclosed a positive spike preceding myoclonic jerks. In one of these patients, the amplitude of the positive spike decreased once myoclonus improved.

CONCLUSION

TMA occurred in aged patients with mild chronic systemic diseases. JLA findings and the absence of giant SEPs further support that TMA is a cortical non-reflex myoclonus. In addition, transient hyperexcitability at the primary motor cortex disclosed by JLA correlated well with its transient symptoms.

Multifocal myoclonus induced by haloperidol

Haloperidol has long been used to manage agitation in dementia, but it is associated with increased side effects. We report the first case of a patient with severe Alzheimer's disease who presented with non-epileptic myoclonus just after haloperidol treatment was initiated.