Myoclonus: current concepts and recent advances

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.

Spatial and temporal properties of tic-related neuronal activity in the cortico-basal ganglia loop

Motor tics are involuntary brief muscle contractions that interfere with ongoing behavior and appear as a symptom in several human disorders. While the pathophysiology of tics is still largely unknown, multiple lines of evidence suggest the involvement of the corticobasal ganglia loop in tic disorders. We administered local microinjections of bicuculline into the putamen of Macaca fascicularis monkeys to induce motor tics, while simultaneously recording neuronal activity from the primary motor cortex, putamen, and globus pallidus. These data were used to explore the spatial and temporal properties of tic-related neuronal activity within the cortico-basal ganglia system. In the putamen, tics were associated with brief bursts of activity of phasically active neurons (presumably the projection neurons) and complex excitation-inhibition patterns of tonically active neurons. Tic-related activity within the putamen was spatially focused and somatotopically organized. In the globus pallidus, tic-related activity was diffusely distributed throughout the motor territory. Tic-related activity in the putamen usually preceded the tic-related activations in the cortex, but in the globus pallidus, tic-related activity was mostly later than the cortex. These findings shed new light on the role of the different basal ganglia nuclei in the generation of motor tics. Despite the early and somatotopically focused nature of tic-related activity in the input stage of the basal ganglia, tic-related activity in the output nucleus is temporally late and diffusely distributed, making it incompatible with a role in tic initiation. Instead, abnormal basal ganglia activity may serve to modulate motor patterns or activate learning mechanisms, thus augmenting further tic expression.

Late-onset asymmetric myoclonus: an emerging syndrome

BACKGROUND

Asymmetric cortical myoclonus is typically thought to be associated with either contralateral cortical structural lesions or degenerative disorders such as corticobasal degeneration when onset is in middle-aged or aged adults. This view has been challenged after a recent case series brought to light a syndrome of senile-onset, asymmetric cortical myoclonus not associated with any such identifiable disorders, thus, named "primary progressive myoclonus of aging." This is rare and no other reports have been published; hence, further such cases need to be highlighted.

CASE REPORTS

Here, we describe 3 patients with some similarities, namely, adult-onset, asymmetric myoclonus that is most likely to be cortical, with an unremarkable thorough diagnostic workup, but with younger age at onset and longer follow-up time.

CONCLUSIONS

This report expands on previous phenotypical descriptions attempting to further develop and refine this possible diagnostic entity.

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.

Myoclonus

Myoclonus can be classified as physiologic, essential, epileptic, and symptomatic. Animal models of myoclonus include DDT and posthypoxic myoclonus in the rat. 5-Hydrotryptophan, clonazepam, and valproic acid suppress myoclonus induced by posthypoxia. The diagnostic evaluation of myoclonus is complex and involves an extensive work-up including basic electrolytes, glucose, renal and hepatic function tests, paraneoplastic antibodies, drug and toxicology screens, thyroid antibody and function studies, neurophysiology testing, imaging, and tests for malabsorption disorders, assays for enzyme deficiencies, tissue biopsy, copper studies, alpha-fetoprotein, cytogenetic analysis, radiosensitivity DNA synthesis, genetic testing for inherited disorders, and mitochondrial function studies. Treatment of myoclonus is targeted to the underlying disorder. If myoclonus physiology cannot be demonstrated, treatment should be aimed at the common pattern of symptoms. If the diagnosis is not known, treatment could be directed empirically at cortical myoclonus as the most common physiology. In cortical myoclonus, the most effective drugs are sodium valproic acid, clonazepam, levetiracetam, and piracetam. For cortical-subcortical myoclonus, valproic acid is the drug of choice. Here, lamotrigine can be used either alone or in combination with valproic acid. Ethosuximide, levetiracetam, or zonisamide can also be used as adjunct therapy with valproic acid. A ketogenic diet can be considered if everything else fails. Subcortical-nonsegmental myoclonus may respond to clonazepam and deep-brain stimulation. Rituximab, adrenocorticotropic hormone, high-dose dexamethasone pulse, or plasmapheresis have been reported to improve opsoclonus myoclonus syndrome. Reticular reflex myoclonus can be treated with clonazepam, diazepam and 5-hydrotryptophan. For palatal myoclonus, a variety of drugs have been used.

Recurrent spinal myoclonus after two episodes of spinal anesthesia at a 1-year interval -A case report-

Spinal myoclonus is an unusual, self-limiting, adverse event that may occur during spinal anesthesia. The exact cause and underlying biochemical mechanism of spinal myoclonus remain unclear. A few cases of spinal myoclonus have been reported after administration of intrathecal bupivacaine. We report a case in which spinal myoclonus recurred after two episodes of spinal anesthesia with bupivacaine at a 1-year interval in a 35-year-old woman. The myoclonus was acute and transient. The patient recovered completely, with no neurologic sequelae.

Definition and classification of hyperkinetic movements in childhood

Hyperkinetic movements are unwanted or excess movements that are frequently seen in children with neurologic disorders. They are an important clinical finding with significant implications for diagnosis and treatment. However, the lack of agreement on standard terminology and definitions interferes with clinical treatment and research. We describe definitions of dystonia, chorea, athetosis, myoclonus, tremor, tics, and stereotypies that arose from a consensus meeting in June 2008 of specialists from different clinical and basic science fields. Dystonia is a movement disorder in which involuntary sustained or intermittent muscle contractions cause twisting and repetitive movements, abnormal postures, or both. Chorea is an ongoing random-appearing sequence of one or more discrete involuntary movements or movement fragments. Athetosis is a slow, continuous, involuntary writhing movement that prevents maintenance of a stable posture. Myoclonus is a sequence of repeated, often nonrhythmic, brief shock-like jerks due to sudden involuntary contraction or relaxation of one or more muscles. Tremor is a rhythmic back-and-forth or oscillating involuntary movement about a joint axis. Tics are repeated, individually recognizable, intermittent movements or movement fragments that are almost always briefly suppressible and are usually associated with awareness of an urge to perform the movement. Stereotypies are repetitive, simple movements that can be voluntarily suppressed. We provide recommended techniques for clinical examination and suggestions for differentiating between the different types of hyperkinetic movements, noting that there may be overlap between conditions. These definitions and the diagnostic recommendations are intended to be reliable and useful for clinical practice, communication between clinicians and researchers, and for the design of quantitative tests that will guide and assess the outcome of future clinical trials.

Management of patients with myoclonus: available therapies and the need for an evidence-based approach

Myoclonus is a hyperkinetic movement disorder characterised by quick and involuntary jerks. Therapy should focus on cure of an underlying disorder; however, symptomatic treatment is often needed when treatment of an underlying cause is impossible or ineffective. The appropriate treatment for a specific type of myoclonus is based on the classification of the anatomical origin of the myoclonus: cortical, subcortical, spinal, or peripheral. We outline criteria for classification and present an overview of the available therapeutic options for the different types of myoclonus. Because of a generally low level of evidence, therapeutic options mainly rely on small observational studies and expert opinion. For an evidence-based approach in the future, randomised controlled trials of symptomatic therapies for myoclonus in homogeneous patient groups are needed.

Propriospinal myoclonus in a child

A 6-year-old girl was experiencing repetitive involuntary and massive jerks immediately involving limbs and trunk. The first motor events appeared approximately at 1 year old and only 5 months after a back trauma. Myoclonus became progressively more frequent and more violent, causing episodes of falls. Neurological examination showed jerks characterized by upper limb abduction, lower limb abduction, and head-body hyperextension. Apart from these motor events, the neurological examination was normal. The results of vitamin B(12) and folate, antinuclear antibody, anti-DNA, anti-Tiroglobulin, anti-thyroid peroxidase antibody, lupus anticoagulant, anti-cardiolipin antibody, rheumatoid factor, and C3 and C4 were unexceptional. Electroencephalography and brain and spinal magnetic resonance imaging were unremarkable. Electromyographic records with surface electrodes showed that duration of myoclonic jerks was ranging from 100 to 300 ms. We thought she had propriospinal myoclonus because of presence of the spreading through the shoulder, upper limbs, and lower limbs in addition to thoracolumbar paraspinal muscles.

Cerebellum can be a possible generator of progressive myoclonus

A 19-month-old girl presented with progressive myoclonic jerking of both proximal lower extremities. On her brain magnetic resonance imaging (MRI), the authors found an ill-defined mass involving cerebellar vermis and the right middle cerebellar peduncle. ( 11)C-methionine positron emission tomography (PET) showed no abnormalities, but (18)F-fluorodeoxyglucose ((18)F-FDG) PET revealed a well-defined hypermetabolic focus. Depth electrodes were inserted deep into the mass, which recorded focal slow waves associated with the clinical myoclonus. Following the removal of the tumor, the myoclonus was completely resolved with no neurological deficit. Here, the authors present a case showing progressive myoclonus associated with a cerebellar ganglioglioma with the electrophysiological data, which provides strong supportive evidence that the cerebellum can be a myoclonus generator.

Benign neonatal sleep myoclonus: a review of the literature

OBJECTIVE

Neurologically normal term infants sometimes present with repetitive, rhythmic myoclonic jerks that occur during sleep. The condition, which is traditionally resolved by 3 months of age with no sequelae, is termed benign neonatal sleep myoclonus. The goal of this review was to synthesize the published literature on benign neonatal sleep myoclonus.

METHODS

The US National Library of Medicine database and the Web-based search engine Google, through June 2009, were used as data sources. All articles published after the seminal description in 1982 as full-length articles or letters were collected. Reports that were published in languages other than English, French, German, Italian, Portuguese, or Spanish were not considered.

RESULTS

We included 24 reports in which 164 term-born (96%) or near-term-born (4%) infants were described. Neonatal sleep myoclonus occurred in all sleep stages, disappeared after arousal, and was induced by rocking the infant or repetitive sound stimuli. Furthermore, in affected infants, jerks stopped or even worsened by holding the limbs or on medication with antiepileptic drugs. Finally, benign neonatal sleep myoclonus did not resolve by 3 months of age in one-third of the infants.

CONCLUSIONS

This review provides new insights into the clinical features and natural course of benign neonatal sleep myoclonus. The most significant limitation of the review comes from the small number of reported cases.

The clinical approach to movement disorders

Movement disorders are commonly encountered in the clinic. In this Review, aimed at trainees and general neurologists, we provide a practical step-by-step approach to help clinicians in their 'pattern recognition' of movement disorders, as part of a process that ultimately leads to the diagnosis. The key to success is establishing the phenomenology of the clinical syndrome, which is determined from the specific combination of the dominant movement disorder, other abnormal movements in patients presenting with a mixed movement disorder, and a set of associated neurological and non-neurological abnormalities. Definition of the clinical syndrome in this manner should, in turn, result in a differential diagnosis. Sometimes, simple pattern recognition will suffice and lead directly to the diagnosis, but often ancillary investigations, guided by the dominant movement disorder, are required. We illustrate this diagnostic process for the most common types of movement disorder, namely, akinetic-rigid syndromes and the various types of hyperkinetic disorders (myoclonus, chorea, tics, dystonia and tremor).

Post-cardiac arrest syndrome: Epidemiology, pathophysiology, treatment, and prognostication: A scientific statement from the International Liaison Committee on Resuscitation; the American Heart Association Emergency Cardiovascular Care Committee; the Council on Cardiovascular Surgery and Anesthesia; the Council on Cardiopulmonary, Perioperative, and Critical Care; the Council on Clinical Cardiology; the Council on Stroke (Part 1)

AIM OF THE REVIEW

To review the epidemiology, pathophysiology, treatment and prognostication in relation to the post-cardiac arrest syndrome.

METHODS

Relevant articles were identified using PubMed, EMBASE and an American Heart Association EndNote master resuscitation reference library, supplemented by hand searches of key papers. Writing groups comprising international experts were assigned to each section. Drafts of the document were circulated to all authors for comment and amendment.

RESULTS

The 4 key components of post-cardiac arrest syndrome were identified as (1) post-cardiac arrest brain injury, (2) post-cardiac arrest myocardial dysfunction, (3) systemic ischaemia/reperfusion response, and (4) persistent precipitating pathology.

CONCLUSIONS

A growing body of knowledge suggests that the individual components of the postcardiac arrest syndrome are potentially treatable.

Central neuraxial anaesthesia presenting with spinal myoclonus in the perioperative period: a case series

Introduction

Perioperative spinal myoclonus is extremely rare. Many anaesthetists and perioperative practitioners may not diagnose or manage this complication appropriately when it occurs. This case report of unusual acute spinal myoclonus following regional anaesthesia highlights certain aspects of this rare complication that have not previously been published.

Case presentations

A series of four consecutive patients who developed acute lower-limb myoclonus following spinal or epidural anaesthesia are described. The case series occurred at three different hospitals and involved four anaesthetists over a 3-year period. Two Caucasian men, aged 90-years-old and 67-years-old, manifested unilateral myoclonus. Two Caucasian women, aged 64-years-old and 53-years-old, developed bilateral myoclonus. Myoclonus was self-limiting in one patient, treated with further regional anaesthesia in one patient and treated with intravenous midazolam in two patients. The overall outcome was good in all patients, with no recurrence or sequelae in any of the patients.

Conclusion

This case series emphasizes that spinal myoclonus following regional anaesthesia is rare, has diverse pathophysiology and can have diverse presentations. The treatment of perioperative spinal myoclonus should be directed at the aetiology. Anaesthetists and perioperative practitioners who are unfamiliar with this rare complication should be reassured that it may be treated successfully with midazolam.

Adult onset familial cherry-red spot myoclonus

We report a case of a 36-year-old woman with progressive generalized myoclonus that first became apparent 9 years ago. Her younger brother had similar problems. Examination of her eyes revealed cherry-red spots. Hexosaminidase A, β-galactosidase and neuraminidase activity were normal. Although the laboratory findings were negative, cherry-red spots, progressive myoclonus and autosomal recessive inheritance pattern suggested that she had an unknown type of lysosomal storage disease.

The borderland of epilepsy: clinical and molecular features of phenomena that mimic epileptic seizures

Paroxysmal losses of consciousness and other episodic neurological symptoms have many causes. Distinguishing epileptic from non-epileptic disorders is fundamental to diagnosis, but even this basic dichotomy is often challenging and is certainly not new. In 1907, the British neurologist William Richard Gowers published his book The Border-land of Epilepsy in which he discussed paroxysmal conditions "in the border-land of epilepsy-near it, but not of it" and their clinical differentiation from epilepsy itself. Now, a century later, we revisit the epilepsy borderland, focusing on syncope, migraine, vertigo, parasomnias, and some rarer paroxysmal disorders. For each condition, we review the clinical distinction from epileptic seizures. We then integrate current understanding of the molecular pathophysiology of these disorders into this clinical framework. This analysis shows that, although the clinical manifestations of paroxysmal disorders are highly heterogeneous, striking similarities in molecular pathophysiology are seen among many epileptic and non-epileptic paroxysmal phenomena.

Primary progressive myoclonus of aging

Myoclonus in older individuals usually occurs in the context of associated neurologic features which allow the diagnosis of the underlying disorder. We encountered 7 patients with a newly recognized myoclonus syndrome; we use the term primary progressive myoclonus of aging (PPMA) for this syndrome. Our purpose was to characterize the clinical and electrophysiological properties of this syndrome. Our database was searched for the presence of "myoclonus" in the physical examination. Medical records and laboratory data were retrospectively reviewed, including electrophysiology data. We applied our criteria for PPMA: (1) asymmetric symptomatic action myoclonus, (2) >/=65 years of age, (3) cortical myoclonus physiology, (4) no dementia, (5) no associated features of defined neurodegenerative disorders, and (6) no secondary cause found. Seven patients fulfilled criteria. Age at presentation ranged from 70 to 87 years. Mean duration from myoclonus onset to last follow-up was 2.9 years. Electrophysiology showed positive-negative back-averaged transients, consistent with cortical myoclonus. No patient demonstrated dementia. Brain imaging in all cases was unremarkable. PPMA is a unique syndrome with characteristic findings that differentiate it from dementias and defined neurodegenerative syndromes. It is important to distinguish primary PPMA from other syndromes seen in older individuals to avoid diagnostic confusion. Some cases showed a response to levetiracetam.

Parkinsonism & related disorders. Myoclonus

Myoclonus has now been recognized to have many possible etiologies, anatomical sources, and pathophysiologic features. Classification schemes may be based on clinical syndromes and etiology, neurophysiology properties, or exam findings. In recent years, many myoclonus case reports and short series have been published. However, this article will group new developments into three areas: (1) Myoclonus in parkinsonian disorders, (2) Concepts in myoclonus generation, and (3) Treatment. Current findings do not allow one to conclude whether or how parkinsonism contributes to the myoclonus mechanism in parkinsonian disorders. Therefore, it seems unlikely that the myoclonus in Lewy body disorders is mostly caused by abnormal basal ganglia input to motor areas of the neocortex. The exact source of cortical myoclonus generation is controversial. Increased corticomuscular coherence represents a robust phenomenon that will need to be explained by any model that offers a putative explanation for cortical myoclonus generation. Myoclonus treatment is still limited, and more research on basic mechanisms before truly effective treatment will be available. The best approach for myoclonus is based on the physiological classification of the myoclonus.

Segmental spinal myoclonus and metastatic cervical ganglioglioma: an unusual association

Segmental spinal myoclonus rarely occurs in association with spinal cord tumor. Only 3 cases have been reported in children so far, mainly concerning astrocytomas of the thoracic spinal cord. We report on a 2-year-old boy suffering from segmental spinal myoclonus involving the upper limbs and harboring a cervical tumor. The clinical and electrophysiological features ruled out a myoclonus of different origin (cortical, subcortical, propriospinal) other than other types of movement disorders. Neuroimaging and histological examinations showed the exceptional presence of a ganglioglioma as the cause of the segmental spinal myoclonus. The clinical and electrophysiological characteristics as well as the possible etiopathogenesis and differential diagnosis are discussed on the basis of the pertinent literature to add some more information about the unusual association between spinal cord tumors and spinal myoclonus.

A Patient with Intractable Posthypoxic Myoclonus (Lance-Adams Syndrome) Treated with Sodium Oxybate

Posthypoxic myoclonus is a rare and devastating complication of near-fatal cardiopulmonary arrest. Despite treatment with available anti-myoclonic agents, some patients may recover cognitively but remain completely disabled by severe myoclonus. We report a 16-year-old patient with severe treatment-refractory posthypoxic myoclonus, which improved markedly with administration of the drug sodium oxybate.

[Differential diagnosis of status epilepticus]

The diagnosis of status epilepticus can be retained, wrongly, in several circumstances. Nonepileptic pseudoseizures from a psychiatric origin and some movement disorders can mimic convulsive status epilepticus. Encephalopathy of various causes (post-anoxic, metabolic, toxic, Creutzfeldt-Jakob disease) can be wrongly taken for non-convulsive status epilepticus, mainly due to inadequate interpretation of the electroencephalogram (EEG). In these encephalopathies, the existence of (non-epileptic) myoclonus and the abolition of the EEG abnormalities with the use of a benzodiazepine (without correction of the clinical symptoms) are additional confounding factors, leading to false diagnosis. Nevertheless, in general, the diagnosis of status epilepticus can be confirmed or rejected base on a combined analysis of the clinical data and the EEG.

Polymyography in the diagnosis of childhood onset movement disorders

We report on the results of a clinical and polymyographic retrospective study of 61 paediatric patients with tremor, dystonia and/or myoclonus. Aim of the study was to verify the contribution of polymyography in the classification of these movement disorders and in their aetiological definition.

METHODS

The movement disorders were clinically classified by two experts, based on clinical and videotape recordings evaluation; all patients underwent standardized polymyographic evaluation; aetiological diagnosis was performed according to diagnostic protocols for dystonia, myoclonus, tremor and psychogenic movement disorders. The polymyographic features were summarized in five different patterns (dystonia, subcortical myoclonus, myoclonic dystonia, tremor, normal) and compared with the clinical classification and with aetiological diagnosis.

RESULTS

In more than 70% of the patients the polymyographic features were in accordance with the clinical classification; in 31% the polymyographic features allowed to identify a clinically unclassified movement disorder and in 19.6% disclosed a not clinically evident associated movement disorder. The polymyographic study did not contribute to the aetiological diagnosis, but was useful in supporting the clinical diagnosis of psychogenic movement disorder.

Post-cardiac arrest syndrome: epidemiology, pathophysiology, treatment, and prognostication. A Scientific Statement from the International Liaison Committee on Resuscitation; the American Heart Association Emergency Cardiovascular Care Committee; the Council on Cardiovascular Surgery and Anesthesia; the Council on Cardiopulmonary, Perioperative, and Critical Care; the Council on Clinical Cardiology; the Council on Stroke

AIM OF THE REVIEW

To review the epidemiology, pathophysiology, treatment and prognostication in relation to the post-cardiac arrest syndrome.

METHODS

Relevant articles were identified using PubMed, EMBASE and an American Heart Association EndNote master resuscitation reference library, supplemented by hand searches of key papers. Writing groups comprising international experts were assigned to each section. Drafts of the document were circulated to all authors for comment and amendment.

RESULTS

The 4 key components of post-cardiac arrest syndrome were identified as (1) post-cardiac arrest brain injury, (2) post-cardiac arrest myocardial dysfunction, (3) systemic ischaemia/reperfusion response, and (4) persistent precipitating pathology.

CONCLUSIONS

A growing body of knowledge suggests that the individual components of the post-cardiac arrest syndrome are potentially treatable.

Opsoclonus-myoclonus-ataxia syndrome with autoantibodies to glutamic acid decarboxylase

Opsoclonus-myoclonus-ataxia syndrome (OMS) is a rare neurological disorder of probably autoimmune origin. Most cases are associated with a remote neoplasm or a viral infection; however in some instances no underlying aetiology can be demonstrated. We report the presence of anti-glutamic acid decarboxylase antibodies (anti-GAD Abs) in the serum and CSF of a patient with idiopathic OMS. Treatment with intravenous immunoglobulin led to a remarkable clinical improvement with parallel reduction of anti-GAD titers. Anti-GAD Abs have been associated with several neurological syndromes. They could also be responsible for the clinical triad of OMS, by impairing GABAergic transmission in specific brainstem and cerebellar circuits. We propose that testing for anti-GAD Abs should be performed in OMS, especially when no other aetiological association can be demonstrated.

Spinal myoclonus associated with vitamin B12 deficiency

We report a 85-year-old female patient with involuntary and regular movements restricted to abdominal muscles, resembling belly dance, with additional clinical features; ataxia, impaired cognition, neuropathy and glossitis. We initially excluded the possible cortical and spinal structural abnormalities with magnetic resonance imagings and performed routine blood analysis which revealed that serum vitamin B12 (vB12) level was under normal ranges. The relation of low serum vB12 level and myoclonus is speculative and very few studies have demonstrated such patients. In this case report, serum vB12 deficiency is discussed in the context of its probable role in the generation of spinal myoclonus.

Febrile myoclonus

Febrile myoclonus is a poorly understood and rarely reported phenomenon. We report a case with particular characteristics that continue to help define this benign disorder.

Belly dancer's myoclonus and chronic abdominal pain: Pain-related dysinhibition of a spinal cord central pattern generator?

We report on a patient with segmental rhythmic myoclonus resembling belly dance. This patient developed the myoclonus in temporal and anatomical association with chronic abdominal pain. No structural or metabolic abnormalities were found. EMG recordings suggested the presence of a spinal cord central pattern generator (CPG). We hypothesize that pain-related spinal plasticity might have contributed to the hyperactivity of a spinal CPG, thus leading to the myoclonic jerks in our patient.