Gait apraxia: further clues to localization

Inhibitory control of gait initiation in humans: An electroencephalography study

Response inhibition is a crucial component of executive control. Although mainly studied in upper limb tasks, it is fully implicated in gait initiation. Here, we assessed the influence of proactive and reactive inhibitory control during gait initiation in healthy adult participants. For this purpose, we measured kinematics and electroencephalography (EEG) activity (event-related potential [ERP] and time-frequency data) during a modified Go/NoGo gait initiation task in 23 healthy adults. The task comprised Go-certain, Go-uncertain, and NoGo conditions. Each trial included preparatory and imperative stimuli. Our results showed that go-uncertainty resulted in delayed reaction time, without any difference for the other parameters of gait initiation. Proactive inhibition, that is, Go uncertain versus Go certain conditions, influenced EEG activity as soon as the preparatory stimulus. Moreover, both proactive and reactive inhibition influenced the amplitude of the ERPs (central P1, occipito-parietal N1, and N2/P3) and theta and alpha/low beta band activities in response to the imperative-Go-uncertain versus Go-certain and NoGo versus Go-uncertain-stimuli. These findings demonstrate that the uncertainty context; induced proactive inhibition, as reflected in delayed gait initiation. Proactive and reactive inhibition elicited extended and overlapping modulations of ERP and time-frequency activities. This study shows the protracted influence of inhibitory control in gait initiation.

Gait Apraxia and Hakim's Disease: A Historical Review

In 1965, Prof. Salomón Hakim described, for the first time, a condition characterized by normal pressure hydrocephalus and gait alterations. During the following decades, definitions such as "Frontal Gait", "Bruns' Ataxia" and "Gait Apraxia" have been frequently used in pertinent literature in the attempt to best define this peculiar motor disturbance. More recently, gait analysis has further shed light on the typical spatiotemporal gait alterations that characterize this neurological condition, but a clear and shared definition of this motor condition is still lacking. In this historical review, we described the origins of the terms "Gait Apraxia", "Frontal Gait" and "Bruns' Ataxia", starting with the first works of Carl Maria Finkelburg, Fritsch and Hitzig and Steinthal during the second half of the 19th century and ending with Hakim's studies and his formal definition of idiopathic normal pressure hydrocephalus (iNPH). In the second part of the review, we analyze how and why these definitions of gait have been associated with Hakim's disease in the literature from 1965 to the present day. The definition of "Gait and Postural Transition Apraxia" is then proposed, but fundamental questions about the nature and mechanisms underlying this condition remain unanswered.

Concurrent Spinal and Intracranial Subdural Hematomas as a Cause of Near-Fatal Low Back Pain in the Chiropractic Office: A Case Report

In older individuals, minor trauma may cause potentially fatal intracranial subdural hematoma (SDH). Rarely, these patients present with only low back and radicular pain as gravity redistributes the SDH to the lumbar spine. A 69-year-old male presented to a chiropractor with a 10-day history of acute on chronic low back pain, which radiated into his lower extremities bilaterally, involving weakness and difficulty walking, and a ground-level fall onto his elbows 16 days prior. He had visited his primary care provider, orthopedist, and traditional Chinese medicine practitioner, received oral analgesics and three ketorolac injections, and had lumbar radiographs, followed by acupuncture, cupping, and spinal manipulation without lasting relief. Considering the patient's concerning presentation, the chiropractor ordered lumbar magnetic resonance imaging (MRI) on the first visit, revealing findings suggestive of late subacute lumbar SDH, and recommended urgent brain MRI and neurosurgical referral. The patient went to an orthopedic surgeon at a nearby hospital, becoming disoriented upon presentation, prompting admission. Brain MRI confirmed bilateral chronic intracranial SDH, prompting emergency hematoma evacuation via burr hole craniostomy. The patient's gait rapidly improved, and the pain subsided over the following two weeks. This case highlights an older male identified as having spinal SDH by a chiropractor, leading to referral and surgery for concurrent life-threatening intracranial SDH. Clinicians should be aware that spinal SDH may stem from asymptomatic intracranial SDH and should be suspicious of SDH in older individuals after a fall, signs of which warrant emergency referral for MRI and surgical evaluation.

Gait Apraxia with Exaggerated Upper Limb Movements as Presentation of AARS2 Related Leukoencephalopathy

A 55-year-old male presented with apraxia of gait with exaggerated upper limb movement with relative preservation of cognition and mild spasticity of limbs. His investigations reveal posterior-predominant leukodystrophy in brain magnetic resonance imaging (MRI) and compound heterozygous mutations in mitochondrial alanyl-transfer RNA synthetase 2 (AARS2) by next generation sequencing. His asymptomatic brother also has MRI changes with subtle mild pyramidal signs. AARS2 mutation is a rare cause of mitochondrial encephalopathy which may give rise to leukodystrophy with premature ovarian failure, infantile cardiomyopathy, lung hypoplasia and myopathy. Gait apraxia as primary presenting feature of this rare variant of mitochondrial encephalomyopathy is hitherto un-reported.

Circumscribed supplementary motor area injury with gait apraxia including freezing of gait and shuffling gait: a case report

Clinical findings in cases of injury circumscribed with SMA is no consensus. We report the case of a 60-year-old male with circumscribed SMA injury who showed freezing of gait, and shuffling gait. Twenty-one days after onset, the patient showed difficulties with the left leg swing in gait initiation (freezing of gait). In steady-state gait, the stride of the left leg swing was short (shuffling gait). Thirty-four days after onset, this phenomenon was not observed during gait. Circumscribed SMA injury can cause gait apraxia, including freezing and shuffling gait, such as in extensive SMA injury in the medial frontal cortex.

Movement disorders in primary central nervous system lymphoma: two unreported cases and a review of literature

BACKGROUND

Recognition of secondary movement disorders (SMDs) is fundamental either to alleviate disabling disturbances or to treat potentially life-threatening conditions, such as brain tumors. Primary CNS lymphoma (PCNSL) is a rare form of CNS cancer that is often located in subcortical areas, accounting for both neuropsychiatric and motoric disorders. Nevertheless, an overview on PCNSL-related movement disorders (MDs) phenomenology has not been provided yet.

OBJECTIVE

To outline the main features of PCNSL-related MDs.

METHODS

A retrospective analysis was conducted on a cohort of patients with PCNSL presenting with MDs, including all existing cases identified by a systematic literature review (source: Medline; period: 1946-2020) and two unreported cases. Data on phenomenology, neuroimaging, histology, and clinical course were collected.

RESULTS

A total cohort of fifteen subjects was defined, enrolling thirteen previously described patients extracted from eleven published studies, and our two unreported cases. A parkinsonian syndrome appearing at about 60 years of age, unresponsive to levodopa, associated to other neurological signs, resulted as the most common presentation of PCNSL-related MD. Chorea, dystonia, and dyskinesia occurred less frequently, with some degree of responsiveness to symptomatic treatments. Basal ganglia were involved in most cases and motoric disturbances often ameliorated after tumor mass reduction.

CONCLUSIONS

This study identified those features of PCNSL-related MDs that could support an appropriate approach to such a rare condition. In fact, while the outcome remains still poor, the therapeutic scenario of PCNSL is changing; an early diagnosis together with an adequate management will be thus crucial for timely and successful interventions.

Diagnostics and treatment of chronic cerebral ischemia

5560 patients with the diagnosis “Other cerebral vascular diseases” per 100 000 of elderly population were registered in RF in 2017. Usually this is a code for chronic brain ischemia (CBI) – the most popular diagnosis in Russian neurological practice. However, diagnostic criteria of CBI are not well defined and need to be ascertained. Recent studies show that the most reliable clinical feature of CBI could be cognitive impairment. It is developed before other clinical signs and correlate with severity of vascular brain lesions. Typically, cognitive impairment is subcortical with prominent bradyphrenia, attentional, dysexecutive and visuospatial deficit and relative sparing of memory. However clinical diagnosis of CBI could be only hypothetical. Diagnosis should be verified by MRI or other visualization technic. Diagnosis is verified if neuroimaging revealed silent strokes, microbleeds and vascular leukoencephalopathy. The most important objective of chronic brain ischemia management is the control of basic vascular disease. Besides this, pathogenetic therapy should be performed to improve cerebral microcirculation, neuronal metabolism and to provide neuroprotection. There is positive data on dipyridamole usage in chronic brain ischemia. It has desagregative, vasotropic, antioxidative and antiinflammation properties. Dypiridamole treatment in CBI patients lead to decrease of neuropsychiatric symptoms and improvement of well-being.

Theoretical framework for "unexplained" dizziness in the elderly: The role of small vessel disease

In this paper we postulate that disruption of connectivity in the human brain can lead to dizziness, a symptom normally associated with focal disease of the vestibular system. The specific case that we will examine is the development of "unexplained" dizziness in the elderly-an extremely common clinical problem. Magnetic resonance imaging of the brain in the elderly usually show variable degrees of multifocal micro-angiopathy (small vessel white matter disease, SVD); thus, we review the literature, present a conceptual model and report preliminary quantitative EEG data in support of the hypothesis that such hemispheric SVD leads to central nervous system disconnection that elderly patients report as dizziness. Loss of connectivity by age-related build-up of SVD could lead to dizzy feelings through one or more of the following mechanisms: disconnection of cortical vestibular centers, disconnection between frontal gait centers and the basal ganglia, and disconnection between intended motor action (efference copy) and sensory re-afference. Finally, we propose that SVD-mediated dysregulation of cerebral blood pressure is linked to dizziness during standing and walking in elderly patients with "unexplained" dizziness.

EEG time-frequency analysis provides arguments for arm swing support in human gait control

BACKGROUND

Human gait benefits from arm swing, which requires four-limb co-ordination. The Supplementary Motor Area (SMA) is involved in multi-limb coordination. With its location anterior to the leg motor cortex and the pattern of its connections, this suggests a distinct role in gait control.

RESEARCH QUESTION

Is the SMA functionally implicated in gait-related arm swing?

METHODS

Ambulant electroencephalography (EEG) was employed during walking with and without arm swing in twenty healthy subjects (mean age: 64.9yrs, SD 7.2). Power changes across the EEG frequency spectrum were assessed by Event Related Spectral Perturbation (ERSP) analysis over both the putative SMA at electrode position Fz and additional sensorimotor regions.

RESULTS

During walking with arm swing, midline electrodes Fz and Cz showed a step-related pattern of Event Related Desynchronization (ERD) followed by Event Related Synchronization (ERS). Walking without arm swing was associated with significant ERD-ERS power reduction in the high-beta/low-gamma band over Fz and a power increase over Cz. Electrodes C3 and C4 revealed a pattern of ERD during contralateral- and ERS during ipsilateral leg swing. This ERD power decreased in gait without arm swing (low-frequency band). The ERSP pattern during walking with arm swing was similar at CP1 and CP2: ERD was seen during double support and the initial swing phase of the right leg, while a strong ERS emerged during the second half of the left leg's swing. Walking without arm swing showed a significant power reduction of this ERD-ERS pattern over CP2, while over CP1, ERS during left leg's swing turned into ERD.

CONCLUSION

The relation between arm swing in walking and a step-related ERD-ERS pattern in the high-beta/low-gamma band over the putative SMA, points at an SMA contribution to integrated cyclic anti-phase movements of upper- and lower limbs. This supports a cortical underpinning of arm swing support in gait control.

Neural Mechanisms Involved in Mental Imagery of Slip-Perturbation While Walking: A Preliminary fMRI Study

Background: Behavioral evidence for cortical involvement in reactive balance control in response to environmental perturbation is established, however, the neural correlates are not known. This study aimed to examine the neural mechanisms involved in reactive balance control for recovery from slip-like perturbations using mental imagery and to evaluate the difference in activation patterns between imagined and observed slipping. Methods: Ten healthy young participants after an exposure to regular walking and slip-perturbation trial on a treadmill, performed mental imagery and observation tasks in the MR scanner. Participants received verbal instructions to imagine walking (IW), observe walking (OW), imagine slipping (IS) and observe slipping (OS) while walking. Results: Analysis using general linear model showed increased activation during IS versus IW condition in precentral gyrus, middle frontal gyrus, superior, middle and transverse temporal gyrus, parahippocampal gyrus, cingulate gyrus, insula, pulvinar nucleus of the thalamus, pons, anterior and posterior cerebellar lobes. During IS versus OS condition, there was additional activation in parahippocampus, cingulate gyrus, inferior parietal lobule, superior temporal, middle and inferior frontal gyrus. Conclusion: The findings of the current study support involvement of higher cortical and subcortical structures in reactive balance control. Greater activation during slipping could be attributed to the complexity of the sensorimotor task and increased demands to maintain postural stability during slipping as compared with regular walking. Furthermore, our findings suggest that mental imagery of slipping recruited greater neural substrates rather than observation of slipping, possibly due to increased sensory, cognitive and perceptual processing demands. New and Noteworthy: The behavioral factors contributing to falls from external perturbations while walking are better understood than neural mechanisms underlying the behavioral response. This study examines the neural activation pattern associated with reactive balance control during slip-like perturbations while walking through an fMRI paradigm. This study identified specific neural mechanisms involved in complex postural movements during sudden perturbations, to particularly determine the role of cortical structures in reactive balance control. It further highlights the specific differences in neural structures involved in regular unperturbed versus perturbed walking.

Apraxia of gait- or apraxia of postural transitions?

"Apraxia of gait" is not a useful concept and freezing of gait should also not be considered an apraxia. The concept of apraxia may, however, be applied to distortions of postural transitions that can accompany fronto-parietal lesions.

Contribution of the supplementary motor area and the cerebellum to the anticipatory postural adjustments and execution phases of human gait initiation

Several brain structures including the brainstem, the cerebellum and the frontal cortico-basal ganglia network, with the primary and premotor areas have been shown to participate in the functional organization of gait initiation and postural control in humans, but their respective roles remain poorly understood. The aim of this study was to better understand the role of the supplementary motor area (SMA) and posterior cerebellum in the gait initiation process. Gait initiation parameters were recorded in 22 controls both before and after continuous theta burst transcranial stimulation (cTBS) of the SMA and cerebellum, and were compared to sham stimulation, using a randomized double-blind design study. The two phases of gait initiation process were analyzed: anticipatory postural adjustments (APAs) and execution, with recordings of soleus and tibialis anterior muscles. Functional inhibition of the SMA led to a shortened APA phase duration with advanced and increased muscle activity; during execution, it also advanced muscle co-activation and decreased the duration of stance soleus activity. Cerebellar functional inhibition did not influence the APA phase duration and amplitude but increased muscle co-activation, it decreased execution duration and showed a trend to increase velocity, with increased swing soleus muscle duration and activity. The results suggest that the SMA contributes to both the timing and amplitude of the APAs with no influence on step execution and the posterior cerebellum in the coupling between the APAs and execution phases and leg muscle activity pattern during gait initiation.

Paroxysmal freezing of gait in a patient with mesial frontal transient ischemic attacks

BACKGROUND

Rare patients have been reported who developed a mixture of gait disturbances following a focal lesion in the frontal lobe. Thus, the exact location of frontal lesion responsible for a specific gait disturbance is not well defined.

CASE PRESENTATION

We describe a 47-year-old man who experienced two episodes of paroxysmal freezing of gait of the right leg. During the attacks, he had no motor weakness, sensory change, or disequilibrium. He had past history of panic attacks. Recently, he had been under severe emotional stress. T2 and diffusion brain magnetic resonance imaging scans were normal. So far, the most likely clinical diagnosis might be functional freezing of gait. However, magnetic resonance angiography showed atherosclerosis in the proximal left anterior cerebral artery. Perfusion scans showed a delayed mean transit time in the left mesial frontal lobe. He developed two more attacks during the four months of follow up.

CONCLUSIONS

The presented case illustrates that the mesial frontal lobe may be important in the pathophysiology of freezing of gait. We speculate that the supplementary motor area may generate a neuronal command for the initiation of locomotion that in our case may have been inhibited by a transient ischemia.

Lesions causing freezing of gait localize to a cerebellar functional network

OBJECTIVE

Freezing of gait is a disabling symptom in Parkinson disease and related disorders, but the brain regions involved in symptom generation remain unclear. Here we analyze brain lesions causing acute onset freezing of gait to identify regions causally involved in symptom generation.

METHODS

Fourteen cases of lesion-induced freezing of gait were identified from the literature, and lesions were mapped to a common brain atlas. Because lesion-induced symptoms can come from sites connected to the lesion location, not just the lesion location itself, we also identified brain regions functionally connected to each lesion location. This technique, termed lesion network mapping, has been recently shown to identify regions involved in symptom generation across a variety of lesion-induced disorders.

RESULTS

Lesion location was heterogeneous, and no single region could be considered necessary for symptom generation. However, > 90% (13 of 14) of lesions were functionally connected to a focal area in the dorsal medial cerebellum. This cerebellar area overlapped previously recognized regions that are activated by locomotor tasks, termed the cerebellar locomotor region. Connectivity to this region was specific to lesions causing freezing of gait compared to lesions causing other movement disorders (hemichorea or asterixis).

INTERPRETATION

Lesions causing freezing of gait are located within a common functional network characterized by connectivity to the cerebellar locomotor region. These results based on causal brain lesions complement prior neuroimaging studies in Parkinson disease patients, advancing our understanding of the brain regions involved in freezing of gait. ANN NEUROL 2017;81:129-141.

Confined anterior cerebral artery infarction manifesting as isolated unilateral axial weakness

We describe isolated unilateral axial weakness in three patients eventually diagnosed with anterior cerebral artery infarction (ACAI), a new clinical observation. Files of three ACAI patients (2 females, 1 male, ages 55-80) were retrospectively reviewed. All three presented to the ED with sudden unsteadiness. On initial neurological examination, all three patients manifested unilateral truncal deviation to the side contralateral to the weakness, even while seated. There was significant unilateral hypotonia due to substantial paravertebral weakness. None had pyramidal signs or increased limb tone. Speech, language, and cognitive performance were intact during admission examination. In all three patients, initial diffusion-weighted imaging (DWI) MRI showed small confined regions of restriction involving the posterolateral border of ACA territory; CT angiography was normal in one patient with a newly diagnosed atrial fibrillation but showed atherosclerotic vasculature with severe narrowing of the A3 segment of the ACA in two. Awareness of ACAI presenting as unilateral axial weakness is warranted. We suggest that optimal diagnostic management should include examination of axial tone. Ischemic involvement of distal ACA branches may herald a more extensive ACAI. Prompt diagnosis may enable thrombolysis or endovascular treatment, and blood pressure maintenance may allow adequate perfusion to damaged tissue.

Hemodynamic Response of the Supplementary Motor Area during Locomotor Tasks with Upright versus Horizontal Postures in Humans

To understand cortical mechanisms related to truncal posture control during human locomotion, we investigated hemodynamic responses in the supplementary motor area (SMA) with quadrupedal and bipedal gaits using functional near-infrared spectroscopy in 10 healthy adults. The subjects performed three locomotor tasks where the degree of postural instability varied biomechanically, namely, hand-knee quadrupedal crawling (HKQuad task), upright quadrupedalism using bilateral Lofstrand crutches (UpQuad task), and typical upright bipedalism (UpBi task), on a treadmill. We measured the concentration of oxygenated hemoglobin (oxy-Hb) during the tasks. The oxy-Hb significantly decreased in the SMA during the HKQuad task, whereas it increased during the UpQuad task. No significant responses were observed during the UpBi task. Based on the degree of oxy-Hb responses, we ranked these locomotor tasks as UpQuad > UpBi > HKQuad. The order of the different tasks did not correspond with postural instability of the tasks. However, qualitative inspection of oxy-Hb time courses showed that oxy-Hb waveform patterns differed between upright posture tasks (peak-plateau-trough pattern for the UpQuad and UpBi tasks) and horizontal posture task (downhill pattern for the HKQuad task). Thus, the SMA may contribute to the control of truncal posture accompanying locomotor movements in humans.

Associations between mobility, cognition and callosal integrity in people with parkinsonism

Falls in people with parkinsonism are likely related to both motor and cognitive impairments. In addition to idiopathic Parkinson's disease (PD), some older adults have lower body parkinsonism (a frontal gait disorder), characterized by impaired lower extremity balance and gait as well as cognition, but without tremor or rigidity. Neuroimaging during virtual gait suggests that interhemispheric, prefrontal cortex communication may be involved in locomotion, but contributions of neuroanatomy connecting these regions to objective measures of gait in people with parkinsonism remains unknown. Our objectives were to compare the integrity of fiber tracts connecting prefrontal and sensorimotor cortical regions via the corpus callosum in people with two types of parkinsonism and an age-matched control group and to relate integrity of these callosal fibers with clinical and objective measures of mobility and cognition. We recruited 10 patients with frontal gait disorders, 10 patients with idiopathic PD and 10 age-matched healthy control participants. Participants underwent cognitive and mobility testing as well as diffusion weighted magnetic resonance imaging to quantify white matter microstructural integrity of interhemispheric fiber tracts. People with frontal gait disorders displayed poorer cognitive performance and a slower, wider-based gait compared to subjects with PD and age-matched control subjects. Despite a widespread network of reduced white matter integrity in people with frontal gait disorders, gait and cognitive deficits were solely related to interhemispheric circuitry employing the genu of the corpus callosum. Current results highlight the importance of prefrontal interhemispheric communication for lower extremity control in neurological patients with cognitive dysfunction.

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Those with a frontal gait disorder have a slower, wider-based gait compared to idiopathic PD.

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Gait performance was related to integrity of genu fiber tracts in those with FGD.

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Prefrontal cortices may become more involved in locomotion with cognitive dysfunction.

Gait and balance disorders

This chapter focuses on one of the most common types of neurologic disorders: altered walking. Walking impairment often reflects disease of the neurologic structures mediating gait, balance or, most often, both. These structures are distributed along the neuraxis. For this reason, this chapter is introduced by a brief description of the neurobiologic underpinning of walking, stressing information that is critical for imaging, namely, the anatomic representation of gait and balance mechanisms. This background is essential not only in order to direct the relevant imaging tools to the regions more likely to be affected but also to interpret correctly imaging findings that may not be related to the walking deficit object of clinical study. The chapter closes with a discussion on how to image some of the most frequent etiologies causing gait or balance impairment. However, it focuses on syndromes not already discussed in other chapters of this volume, such as Parkinson's disease and other movement disorders, already discussed in Chapter 48, or cerebellar ataxia, in Chapter 23, in the previous volume. As regards vascular disease, the spastic hemiplegia most characteristic of brain disease needs little discussion, while the less well-understood effects of microvascular disease are extensively reviewed here, together with the imaging approach.

Gait Apraxia in Multiple Sclerosis

Background:

Gait apraxia is a gait disorder not attributable to motor, cerebellar, or sensory dysfunction. Gait impairment is common in Multiple Sclerosis (MS), but is mostly attributed to spasticity and ataxia. Impairment ratings scales are designed accordingly and do not separately evaluate apraxia.

Objective:

To describe 15 patients with gait apraxia resulting from MS as their major functional impairment.

Methods:

The Mayo Clinic database (1994-2007) was searched for the terms MS and gait apraxia. Inclusion criteria: Definite MS, significant gait apraxia. Exclusion criteria: alternative disorder causing apraxia, predominantly spastic/ataxic gait disorder.

Results:

9 (60%) of the patients were women, and 12 (80%) had a progressive MS course. Gait apraxia was evident at a median of 8 years (range 0-34) following MS onset. Median EDSS at recognition of gait apraxia was 6.5 (range 5-8). Cognitive dysfunction was present in 11 (73%) and neurogenic bladder dysfunction in 14 (93%). The commonest MRI findings were confluent periventricular T2 lesions, T1 hypointensity and generalized cerebral atrophy with symmetrical ex vacuo ventricular enlargement.

Conclusion:

Gait apraxia can cause significant functional impairment in MS patients, and may be underrecognized. The natural course of the neurological deficit in such patients is unknown, and may differ from that of MS patients with other ambulatory disabilities.

Treatment of gait ignition failure with ropinirole

Gait ignition failure (GIF) is a syndrome characterized by hesitation or inability to initiate gait from a static position. It may occur in a variety of conditions, including normal pressure hydrocephalus, subcortical vascular disease, parkinsonian syndromes and a variety of focal lesions. Previous information on the treatment of GIF has been primarily anecdotal, but there have been a few reports of response to dopamine agonists. We report a 63-year-old man with anoxic encephalopathy who developed GIF nine years after the initial anoxic insult. The patient's GIF responded robustly, albeit transiently, to ropinirole. MRI was unrevealing, but a positron emission tomography scan showed hypometabolism in the deep frontal ACA/MCA watershed area; this may have disconnected the basal ganglia from the motor cortex and/or interrupted dopaminergic mesocortical transmission. Our understanding of the pathophysiology and the treatment of GIF remains limited, but there may be at least a limited therapeutic role for dopamine agonists.

Fronto-striatal dysfunction in type 3 familial cortical myoclonic tremor epilepsy occurring during aging

The aim of this work is to study the cognition, progressive gait impairment, and neuroimaging findings in two patients over 65 years old of the previously described type 3 familial cortical myoclonic tremor with epilepsy (FCMTE3). We report investigations in two of these five FCMTE3 subjects over 65 and showing progressive gait disorders. They both had a pseudo-Parkinson's way of walking and visual intolerance to bright light and brightness contrast without EEG abnormalities exacerbating cortical myoclonus or triggering seizure. Case 1 had moderate gait impairment and a severe frontal syndrome. Case 2 had severe gait impairment and diffuse cognitive disorders. Both cases had cortical hypoperfusion (predominantly in the left frontal lobe) and no cerebellar abnormality on cerebral perfusion SPECT. DAT-SPECT showed dopaminergic depletion. These data indicate fronto-striatal dysfunction associated with gait impairment and cognitive disorders appearing after several decades of disease progression. This gives clues to understanding the pathogenesis and evolution of FCMTE3. Permanent myoclonic discharges or long-term valproate treatment may cause significant toxic effects on neurons (dopaminergic and frontal neurons). Further functional and molecular analyses are required in order to better understand this pathology and the consequences of chronic cortical myoclonus.

Diffusion tensor imaging of freezing of gait in patients with white matter changes

BACKGROUND

Freezing of gait is a common and disabling symptom of parkinsonism. However, the corresponding anatomic structures have yet to be clearly elucidated.

METHODS

We performed diffusion tensor imaging on 40 subjects with white matter changes. We compared apparent diffusion coefficient values and fraction anisotropy values of 7 candidate anatomic structures between 14 patients with freezing of gait (freezing of gait group) and 26 without freezing of gait (control group).

RESULTS

Fraction anisotropy values of the bilateral pedunculopontine nucleus, bilateral superior premotor cortex, right orbitofrontal area, and left supplement motor area were significantly lower in the freezing of gait group than in the control group. In contrast, there were no significant differences in apparent diffusion coefficient values between freezing of gait and control groups.

CONCLUSIONS

Our findings suggest that the bilateral pedunculopontine nucleus, bilateral superior premotor cortex, right orbitofrontal area, and left supplement motor area are closely related to freezing of gait.

Freezing of gait: moving forward on a mysterious clinical phenomenon

Freezing of gait (FoG) is a unique and disabling clinical phenomenon characterised by brief episodes of inability to step or by extremely short steps that typically occur on initiating gait or on turning while walking. Patients with FoG, which is a feature of parkinsonian syndromes, show variability in gait metrics between FoG episodes and a substantial reduction in step length with frequent trembling of the legs during FoG episodes. Physiological, functional imaging, and clinical-pathological studies point to disturbances in frontal cortical regions, the basal ganglia, and the midbrain locomotor region as the probable origins of FoG. Medications, deep brain stimulation, and rehabilitation techniques can alleviate symptoms of FoG in some patients, but these treatments lack efficacy in patients with advanced FoG. A better understanding of the phenomenon is needed to aid the development of effective therapeutic strategies.

White matter involvement in idiopathic normal pressure hydrocephalus: a voxel-based diffusion tensor imaging study

The aim of this study was to characterise the white matter damage involved in idiopathic normal pressure hydrocephalus (INPH) using diffusion tensor imaging (DTI) and the relationship between this damage and clinical presentation. Twenty patients with INPH, 20 patients with Alzheimer's disease and 20 patients with idiopathic Parkinson's disease (as disease control groups) were enrolled in this study. Mean diffusivity (MD) and fractional anisotropy (FA) were determined using DTI, and these measures were analysed to compare the INPH group with the control groups and with certain clinical correlates. On average, the supratentorial white matter presented higher MD and lower FA in the INPH group than in the control groups. In the INPH group, the mean hemispheric FA correlated with some of the clinical measures, whereas the mean hemispheric MD did not. On a voxel-based statistical map, white matter involvement with high MD was localised to the periventricular regions, and white matter involvement with low FA was localised to the corpus callosum and the subcortical regions. The total scores on the Frontal Assessment Battery were correlated with the FA in the frontal and parietal subcortical white matter, and an index of gait disturbance was correlated with the FA in the anterior limb of the left internal capsule and under the left supplementary motor area. DTI revealed the presence of white matter involvement in INPH. Whereas white matter regions with high MD were not related to symptom manifestation, those with low FA were related to motor and cognitive dysfunction in INPH.

The clinical manifestations and pathophysiology of cerebral small vessel disease

Small vessel disease (SVD) is responsible for brain chronic circular disorder, and accounts for 20%-30% cases of ischemic stroke as well as cerebral hemorrhage, and to a great extent, encephalopathy. Binswanger's disease and multiple small strokes, which are common in older people, are also closely associated with SVD. These disorders often cause decline in cognition, vascular dementia, impairment in gait and balance, mood depression, and urinary incontinence, and often brings great social and economic burdens. SVD-related encephalopathy increases the incidences of fall, disability and death in elderly people. With the aging of the society, more attention should be paid to the importance of early diagnosis and prophylactic treatment of SVD. Here the clinical manifestations and pathophysiology of SVD are reviewed.

Posterior pusher syndrome: A report of two cases

"Pusher syndrome" is classically described as a disorder of body orientation in the coronal plane. Although it mainly occurs in stroke patients, non-stroke causes have been described. Pusher behaviour is characterized by a tilt towards the contralesional paretic side and a resistance to external attempts to rectify. It may occur with or without hemispatial neglect, which in itself may be the cause of a usually ipsilesional shift of attention and body orientation in the axial plane. In this report we describe two patients with a marked disturbance of body orientation in the sagittal plane with imbalance, posterior tilt and an active resistance to forward pulling or pushing. By analogy we propose the term "posterior pusher" syndrome for the clinical picture.

The supplementary motor area contributes to the timing of the anticipatory postural adjustment during step initiation in participants with and without Parkinson's disease

The supplementary motor area (SMA) is thought to contribute to the generation of anticipatory postural adjustments (APAs, which act to stabilize supporting body segments prior to movement), but its precise role remains unclear. In addition, participants with Parkinson's disease (PD) exhibit impaired function of the SMA as well as decreased amplitudes and altered timing of the APA during step initiation, but the contribution of the SMA to these impairments also remains unclear. To determine how the SMA contributes to generating the APA and to the impaired APAs of participants with PD, we examined the voluntary steps of eight participants with PD and eight participants without PD, before and after disrupting the SMA and dorsolateral premotor cortex (dlPMC), in separate sessions, with 1-Hz repetitive transcranial magnetic stimulation (rTMS). Both groups exhibited decreased durations of their APAs after rTMS over the SMA but not over the dlPMC. Peak amplitudes of the APAs were unaffected by rTMS to either site. The symptom severity of the participants with PD positively correlated with the extent that rTMS over the SMA affected the durations of their APAs. The results suggest that the SMA contributes to the timing of the APA and that participants with PD exhibit impaired timing of their APAs, in part, due to progressive dysfunction of circuits associated with the SMA.

[Astasia-abasia: psychogenic and non-psychogenic causes]

Astasia-abasia is defined as the inability to stand and to walk, despite sparing of motor function underlying the required balance and gestures. Initially, astasia-abasia was considered a psychogenic gait disorder, but later on, the description of "high-order" gait disorders mimicking this pure functional deficit led authors to refer to "astasia-abasia" as a pure descriptive term, without a presupposed etiological or anatomical substrate. In this paper, the main clinical characteristics of both psychogenic and non-psychogenic astasia-abasia are presented and discussed.

Gait disturbance associated with white matter changes: a gait analysis and blood flow study

To clarify the mechanisms underlying gait disturbance secondary to age-related white matter changes (ARWMC), cerebral perfusion was investigated during treadmill walking. Twenty subjects with extensive hyperintensities in the periventricular and deep white matter on T(2)-weighted magnetic resonance images (MRI) were recruited. The ARWMC subjects were classified into gait-disturbed (GD) and non-GD groups according to clinical criteria. All the subjects underwent gait analyses and cerebral perfusion measurements during both gait and rest by using single photon emission computed tomography. The GD group showed greater double support time/phase and stride width, and slower walking velocity, than the non-GD group. In an analysis of pooled data from all the subjects, gait-induced increases in cerebral perfusion were observed in the supplementary motor areas (SMA), lateral premotor cortex (PMC), primary motor and somatosensory areas, visual areas, basal ganglia and cerebellum. A between-group comparison of gait-induced perfusion changes showed relative underactivation of the SMA, thalamus and basal ganglia, together with relative overactivation of the PMC, in the GD group compared with the non-GD group. In a separate correlation analysis including all the subjects, as the double support phase was longer (that was, gait disturbance was more severe), the gait-induced perfusion changes were proportionally reduced in the SMA, visual cortex, and thalamus. The present study suggests that abnormalities in the basal ganglia-thalamo-cortical loops partly explain gait disturbance observed in a subset of subjects with ARWMC.