Negative Myoclonus: Neurophysiological Study and Clinical Impact in Progressive Myoclonus Ataxia

INTRODUCTION

Negative myoclonus (NM) is an involuntary movement caused by a sudden interruption of muscular activity, resulting in gait problems and falls.

OBJECTIVE

To establish frequency, clinical impact, and neurophysiology of NM in progressive myoclonus ataxia (PMA) patients.

METHODS

Clinical, neurophysiological, and genetic data of 14 PMA individuals from University Medical Centre Groningen (UMCG) Expertise Center Movement Disorder Groningen were retrospectively collected. Neurophysiological examination included video-electromyography-accelerometry assessment in all patients and electroencephalography (EEG) examination in 13 individuals. Jerk-locked (or silent period-locked) back-averaging and cortico-muscular coherence (CMC) analysis aided the classification of myoclonus.

RESULTS

NM was present in 6 (NM+) and absent in 8 (NM-) PMA patients. NM+ individuals have more frequent falls (100% vs. 37.5%) and higher scores on the Gross Motor Function Classification System (GMFCS) (4.3 ±0.74 vs. 2.5 ±1.2) than NM- individuals. Genetic background of NM+ included GOSR2 and SEMA6B, while that of NM- included ATM, KCNC3, NUS1, STPBN2, and GOSR2. NM was frequently preceded by positive myoclonus (PM) and silent-period length was between 88 and 194 ms. EEG epileptiform discharges were associated with NM in 2 cases. PM was classified as cortical in 5 NM+ and 2 NM- through EEG inspection, jerk-locked back-averaging, or CMC analysis.

DISCUSSION

Neurophysiological examination is crucial for detecting NM that could be missed on clinical examination due to a preceding PM. Evidence points to a cortical origin of NM, an association with more severe motor phenotype, and suggests the presence of genetic disorders causing either a PMA or progressive myoclonus epilepsy, rather than pure PMA phenotype. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Epilepsy With Eyelid Myoclonia (Jeavons Syndrome)

The purpose of this review is to provide a comprehensive update and highlight the distinct electroclinical features and discuss recent advances in the etiology, pathophysiology, and management strategies of epilepsy with eyelid myoclonia. Recent studies indicate that variations of certain genes including CHD2 (chromodomain helicase DNA-binding protein 2), KCNB1, KIAA2022, and NAA10 may occur in these patients. It has been postulated that the occipital cortex may play a role in the pathophysiology. Recent studies of functional imaging and connectivity of neuronal electrical activity have provided additional evidence to support this hypothesis. The frontal cortex has additionally been implicated, and it has been suggested that the epileptic cortex may extend beyond the occipital cortex to involve the posterior temporal cortex. We update the management strategies and describe tools that may predict seizure persistence. Epilepsy with eyelid myoclonias, or Jeavons syndrome, is an idiopathic generalized epilepsy characterized by the triad of eyelid myoclonia with or without absence seizures, eyelid closure-elicited electroencephalographic (EEG) paroxysms (epileptiform discharges and/or seizures), and photosensitivity. This condition may account for up to 13% of generalized epilepsies. However, it is frequently under-reported and under-recognized. Many of the patients develop medically refractory epilepsy, and seizures tend to persist throughout life.

Neurological and Neuropsychiatric Impacts of COVID-19 Pandemic

BACKGROUND

Albeit primarily a disease of respiratory tract, the 2019 coronavirus infectious disease (COVID-19) has been found to have causal association with a plethora of neurological, neuropsychiatric and psychological effects. This review aims to analyze them with a discussion of evolving therapeutic recommendations.

METHODS

PubMed and Google Scholar were searched from 1 January 2020 to 30 May 2020 with the following key terms: "COVID-19", "SARS-CoV-2", "pandemic", "neuro-COVID", "stroke-COVID", "epilepsy-COVID", "COVID-encephalopathy", "SARS-CoV-2-encephalitis", "SARS-CoV-2-rhabdomyolysis", "COVID-demyelinating disease", "neurological manifestations", "psychosocial manifestations", "treatment recommendations", "COVID-19 and therapeutic changes", "psychiatry", "marginalised", "telemedicine", "mental health", "quarantine", "infodemic" and "social media". A few newspaper reports related to COVID-19 and psychosocial impacts have also been added as per context.

RESULTS

Neurological and neuropsychiatric manifestations of COVID-19 are abundant. Clinical features of both central and peripheral nervous system involvement are evident. These have been categorically analyzed briefly with literature support. Most of the psychological effects are secondary to pandemic-associated regulatory, socioeconomic and psychosocial changes.

CONCLUSION

Neurological and neuropsychiatric manifestations of this disease are only beginning to unravel. This demands a wide index of suspicion for prompt diagnosis of SARS-CoV-2 to prevent further complications and mortality.

Continuous epileptic negative myoclonus as the first seizure type in atypical benign epilepsy with centrotemporal spikes

To figure out which diagnosis is more suitable and which antiepileptic drugs are more sensitive to epileptic negative myoclonus (ENM) as the first seizure type in atypical benign epilepsy with centrotemporal spikes.We reviewed the electroencephalogram (EEG) database of Linyi People's Hospital Affiliated to Shandong University and medical records of patients with ENM onset. The characteristics of epileptic seizures, onset age, treatment process, growth and development history, past disease history, family history, degree of mental deterioration, cranial imaging, and video-EEG were studied retrospectively and followed up.There were 4 cases with ENM onset and 1 with continuous ENM, 3 males and 1 female. The onset age was from 2 years 3 months to 8 years 7 months. The cranial magnetic resonance imaging (MRI) and developmental quotient, as well as the family, personal, and past disease history, were normal. Frequent falls and drops were the main clinical manifestations. Five months after the onset of ENM, case 1 had focal seizures in sleep. ENM was the first and only manifestation in all the other 3 children. Discharges of interictal EEG were in bilateral rolandic areas, especially in midline areas (Cz, Pz), electrical status epilepticus in sleep was found in 3 cases. One child was sensitive to levetiracetam, the other 3 were sensitive to clonazepam.ENM can affect the upper or lower extremities. ENM as the first or only symptom was a special phenomenon in benign epilepsy with centrotemporal spikes (BECTS) variants. Ignorance of midline spikes mainly in Cz or Pz in BECTS might lead to missed diagnosis of ENM. Whether benzodiazepines are viable as a choice of BECTS variants with electrical status epilepticus in sleep when ENM is the first symptom still needs a large sample evidence-based observation.

Physiology-Based Treatment of Myoclonus

Myoclonus can cause significant disability for patients. Myoclonus has a strikingly diverse array of underlying etiologies, clinical presentations, and pathophysiological mechanisms. Treatment of myoclonus is vital to improving the quality of life of patients with these disorders. The optimal treatment strategy for myoclonus is best determined based upon careful evaluation and consideration of the underlying etiology and neurophysiological classification. Electrophysiological testing including EEG (electroencephalogram) and EMG (electromyogram) data is helpful in determining the neurophysiological classification of myoclonus. The neurophysiological subtypes of myoclonus include cortical, cortical-subcortical, subcortical-nonsegmental, segmental, and peripheral. Levetiracetam, valproic acid, and clonazepam are often used to treat cortical myoclonus. In cortical-subcortical myoclonus, treatment of myoclonic seizures is prioritized, valproic acid being the mainstay of therapy. Subcortical-nonsegmental myoclonus may be treated with clonazepam, though numerous agents have been used depending on the etiology. Segmental and peripheral myoclonus are often resistant to treatment, but anticonvulsants and botulinum toxin injections may be of utility depending upon the case. Pharmacological treatments are often hampered by scarce evidence-based knowledge, adverse effects, and variable efficacy of medications.

An Overview of the Electroencephalographic (EEG) Features of Epilepsy with Eyelid Myoclonia (Jeavons Syndrome)

Epilepsy with eyelid myoclonia or Jeavons Syndrome is a unique idiopathic generalized epilepsy with onset in childhood. It is characterized by eyelid myoclonia which may be associated with absence seizures, eyelid closure-induced epileptiform discharges and/or seizures and photosensitivity. It is frequently underrecognized and misdiagnosed because it may be mistaken for some other type of generalized epilepsy or facial tic disorder. The intent of this narrative review is to focus on existing literature and highlight the distinct electroencephalographic features including characteristic eye movements, associated waveforms, interictal and ictal findings that are suggestive and characteristic of Jeavons Syndrome to aid in timely recognition of this syndrome.

Treatment of Movement Disorder Emergencies in Autoimmune Encephalitis in the Neurosciences ICU

Immune response against neuronal and glial cell surface and cytosolic antigens is an important cause of encephalitis. It may be triggered by activation of the immune system in response to an infection (para-infectious), cancer (paraneoplastic), or due to a patient's tendency toward autoimmunity. Antibodies directed toward neuronal cell surface antigens are directly pathogenic, whereas antibodies with intracellular targets may become pathogenic if the antigen is transiently exposed to the cell surface or via activation of cytotoxic T cells. Immune-mediated encephalitis is well recognized and may require intensive care due to status epilepticus, need for invasive ventilation, or dysautonomia. Patients with immune-mediated encephalitis may become critically ill and display clinically complex and challenging to treat movement disorders in over 80% of the cases (Zhang et al. in Neurocrit Care 29(2):264-272, 2018). Treatment options include immunotherapy and symptomatic agents affecting dopamine or acetylcholine neurotransmission. There has been no prior published guidance for management of these movement disorders for the intensivist. Herein, we discuss the immune-mediated encephalitis most likely to cause critical illness, clinical features and mechanisms of movement disorders and propose a management algorithm.

Myoclonus

PURPOSE OF REVIEW

This article offers clinicians a strategic approach for making sense of a symptom complex that contains myoclonus. The article presents an evaluation strategy that highly leverages the two major classification schemes of myoclonus. The goal of this article is to link evaluation strategy with diagnosis and treatment of myoclonus.

RECENT FINDINGS

The growth of medical literature has helped better define myoclonus etiologies. Physiologic study of myoclonus types and etiologies with electrophysiologic testing has provided greater clarity to the pathophysiology of the myoclonus in various diseases. Although studies have been limited, the role of newer treatment agents and methods has made progress.

SUMMARY

Myoclonus has hundreds of different etiologies. Classification is necessary to evaluate myoclonus efficiently and pragmatically. The classification of myoclonus etiology, which is grouped by different clinical presentations, helps determine the etiology and treatment of the myoclonus. The classification of myoclonus physiology using electrophysiologic test results helps determine the pathophysiology of the myoclonus and can be used to strategize symptomatic treatment approaches. Both basic ancillary testing (including EEG and imaging) and more comprehensive testing may be necessary. Treatment of the underlying etiology is the ideal approach. However, if such treatment is not possible or is delayed, symptomatic treatment guided by the myoclonus physiology should be considered. More controlled study of myoclonus treatment is needed. Further research on myoclonus generation mechanisms should shed light on future treatment possibilities.

Biotinidase deficiency in a newborn

INTRODUCTION

Biotinidase deficiency is an inherited disorder of biotin metabolism that is untreated may present within the first few month of life.

OBJECTIVE

We report the exceptional observation of a biotinidase deficiency in Morocco. The rarity of this pathology, its age of onset, its mode of revelation and the lack of treatment in Morocco make the particularity of this observation.

OBSERVATION

A newborn child born from a 24-year-old mother, followed by an estimated pregnancy of 37 weeks of amenorrhea according to the Farr score (morphological maturation score used for the dating of the pregnancy term). The infant presented at 7 days of life with a cutaneous-mucous eruption with icithiosic dry erythroderma of interest to the trunk, the face, the scalp associated with alopecia and depilation of the eyebrow. The biotinoidase deficiency was confirmed by its low serum concentration at 49 nka / l. The newborn died at 20 days of life before starting the specific treatment.

CONCLUSION

Biotinidase deficiency is a rare condition requiring early screening and rapid management. The delay in diagnosis and the unavailability of treatment in Morocco can have fatal consequences.

Stiff limb syndrome with lower limb myoclonus: A case report

RATIONALE

stiff limb syndrome (SLS) is a variant of stiff-man syndrome, primarily affecting a specific limb. Its diagnosis has always been challenging due to the lack of a specific confirmation test. We present a rare case of a patient with lower limb myoclonus and rigidity.

PATIENT CONCERNS

A 53-year-old male presented with a sudden onset of progressive left lower extremity myoclonus and muscle rigidity for 3 days. He rapidly showed signs of right lower limb involvement with severe joint stiffness and inability to walk.

DIAGNOSIS

The symptoms nature, physical examination, careful elimination of differential diagnosis suggested a diagnosis of stiff limb syndrome.

INTERVENTIONS

Intravenous infusion of gamma globulin 0.4 mg/kg coupled with baclofen and clonazepam were given after admission. He also received an injection of botulinum toxin A to relieve his muscle stiffness.

OUTCOMES

The patients' condition improved after the initial treatment with complete disappearance of muscle twitching. Further improvements were seen later on after the local administration of botulinum toxin A.

LESSONS

Stiff limb syndrome shares the same complex symptoms with many other conditions. Its diagnosis relies heavily on clinical presentations and on ruling out other conditions. However, unusual symptoms such as myoclonus can occur in few cases and together with the rarity of the condition, the prevalence of misdiagnosis is high. Therefore, being aware and recognizing the signs and symptoms is crucial for proper management. Additionally, EMG is a very important test if the present condition is suspected. However, a negative EMG result or a negative anti-glutamic acid decarboxylase antibody test should not exclude SLS diagnosis.

Perampanel attenuates myoclonus in a patient with neuronal ceroid lipofuscinoses type 2 disease

Neuronal ceroid lipofuscinoses type 2 disease (CLN2) is a very rare, autosomal recessive neurodegerative disease caused by deficient activity of the enzyme tripeptidyl peptidase 1 (TPP1). The seizures in CLN2 are polymorphic and resistant to antiepileptic drugs. In particular, myoclonus (epileptic and non-epileptic) predominant as the disease progresses. Herein, we present a child of CLN2 disease, who had near-continuous myoclonus, and was subsequently attenuated by administration of Perampanel. This girl had initially presented with language delay and generalized tonic clonic seizure at 3 years of age. The diagnosis of CLN2 was made via genetic study, which showed compound heterozygous mutation on TPP1 gene (c.622 C > T and partial gene deletion including at least exons 1-3). Currently, at the age of 8 years, there was near-continuous myoclonus (epileptic and non-epileptic), which worsen during acute illness. Eventually, she was given Perampanel with starting dose of 1 mg/day and slowly titrated upto 6 mg/day in 4 weeks. There was significant attenuation of myoclonus (>50% seizure reduction). To our knowledge, this is the first case in the literature describing the efficacy of perampanel in treating myoclonus in CLN2 disease.

Low-dose perampanel improves refractory cortical myoclonus by the dispersed and suppressed paroxysmal depolarization shifts in the sensorimotor cortex

OBJECTIVE

To elucidate the effects of perampanel (PER) on refractory cortical myoclonus for dose, etiology and somatosensory-evoked potential (SEP) findings.

METHODS

We examined 18 epilepsy patients with seizure and cortical myoclonus. Based on data accumulated before and after PER treatment, correlations among clinical scores in myoclonus and activities of daily life (ADL); early cortical components of SEP; and PER blood concentration, were analyzed.

RESULTS

PER (mean dose: 3.2 ± 2.1 mg/day) significantly improved seizures, myoclonus and ADL and significantly decreased the amplitude of and prolonged latency of giant SEP components. The degree of P25 and N33 prolongations (23.8 ± 1.6 to 24.7 ± 1.7 ms and 32.1 ± 4.0 to 33.7 ± 3.4 ms) were significantly correlated with improved ADL score (p = 0.019 and p = 0.025) and blood PER concentration (p = 0.011 and p = 0.025), respectively.

CONCLUSIONS

Low-dose PER markedly improved myoclonus and ADL in patients with refractory cortical myoclonus. Our results suggest that SEP, particularly P25 latency, can be used as a potential biomarker for assessing the objective effects of PER on intractable cortical myoclonus.

SIGNIFICANCE

In this study, PER lessened the degree of synchronized discharges in the postsynaptic neurons in the primary motor cortex.

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

OBJECTIVES

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

DESIGN

Case-control study.

SETTING

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

PARTICIPANTS

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

PRIMARY AND SECONDARY OUTCOME MEASURES

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

RESULTS

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

CONCLUSIONS

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

Spinal myoclonus: a rare presentation of cervical myelopathy

Myoclonus describes a movement disorder characterised by brief, abrupt and involuntary contractions of muscles or groups of muscles, usually associated with intracranial lesions, with limited evidence linking it to spinal pathologies. The pathophysiology of spinal myoclonus is extensive and multifactorial. Infection, intramedullary and extramedullary space-occupying lesions, trauma, vascular abnormalities, degenerative processes and cervical spondylosis have been implicated with the disease, the latter been associated with cervical stenosis with no reported cases linking it to an underlying cervical disc herniation. Although medical therapy with clonazepam, levetiracetam, valproate, tetrabenazine hydrochloride and spinal block injections has been equivocal, spinal myoclonus secondary to disc herniation requires surgical intervention. This report describes a case of segmental spinal myoclonus, secondary to a herniated cervical intervertebral disc. After corpectomy and a cage-augmented fusion technique, the myoclonic symptoms resolved. To our knowledge, this was the first report to describe the successful management of discogenic spinal myoclonus with spinal surgery.

Assessment of the Anticonvulsant Potency of Ursolic Acid in Seizure Threshold Tests in Mice

Ursolic acid (UA) is a plant derived compound which is also a component of the standard human diet. It possesses a wide range of pharmacological properties, i.e., antioxidant, anti-inflammatory, antimicrobial and antitumor, which have been used in folk medicine for centuries. Moreover, influence of UA on central nervous system-related processes, i.e., pain, anxiety and depression, was proved in experimental studies. UA also revealed anticonvulsant properties in animal models of epilepsy and seizures. The aim of the present study was to investigate the influence of UA on seizure thresholds in three acute seizure models in mice, i.e., the 6 Hz-induced psychomotor seizure threshold test, the maximal electroshock threshold (MEST) test and the timed intravenous pentylenetetrazole (iv PTZ) infusion test. We also examined its effect on the muscular strength (assessed in the grip strength test) and motor coordination (estimated in the chimney test) in mice. UA at doses of 50 and 100 mg/kg significantly increased the seizure thresholds in the 6 Hz and MEST tests. The studied compound did not influence the seizure thresholds in the iv PTZ test. Moreover, UA did not affect the motor coordination and muscular strength in mice. UA displays only a weak anticonvulsant potential which is dependent on the used seizure model.

Severe chronic lithium intoxication in patient treated for bipolar disorder

OBJECTIVE

Lithium has been long used in psychiatry as an adjuvant treatment for bipolar disorder. Chronic lithium intoxication is very rare.

DESIGN

We present the case of a 72-year-old female, treated with lithium for more than 10 years for bipolar disorder, who was admitted for gait impairment with weakness of limbs, myoclonus, speech impairment and memory disturbances.

RESULTS

Diagnosis of lithium intoxication was based on clinical picture and determination of serum lithium levels. EEG showed severe encephalopathy with triphasic wave complexes. Sensory and motor axonal neuropathy was observed by EMG. Discontinuation of the drug leads to clinical improvement, although not to a fully neurological recovery.

CONCLUSION

Lithium is still very effective drug, but requires regular monitoring of serum levels to prevent overdose and symptoms of intoxication. Neurophysiological methods, including EEG and EMG, are strongly recommended to determine the level of peripheral and/or central nervous system impairment.

[Myoclonus as a movement disorder]

Myoclonus is often a diagnostic and therapeutic challenge due to its broad phenomenological variability and limited therapeutic options. This article gives a short survey and characterizes in detail two common types of myoclonus, cortical myoclonus and reticular reflex myoclonus. Clinical testing and electrophysiological investigations provide relevant local diagnostic indications for the generating structure(s). Such indications would influence not only the strategies of neuroimaging and laboratory investigations aimed at clarifying the underlying cause but also the selection of drugs to suppress myoclonus.

A species dependent response to the pro-epileptic drug pentylentetrazole in birds

Epilepsy is common disorder that affects over 50 million people worldwide. Birds remain a promising yet largely under-explored model of epilepsy. This study reports the comparison of the response of two species of birds, Australian Parrots (APs) and Sparrows (SPs), to a pro-epileptic drug, Pentylenetetrazole (PTZ). PTZ injections caused myoclonic jerks (MCJs) and tonic clonic seizures (TCSs) in both species. The frequency of MCJs in APs was greater at the dose of 75mg/kg compared to both 50mg/kg and 25mg/kg while it was not significantly different in SPs. The comparison of APs and SPs showed that the frequency of MCJs was greater in APs compared to SPs at 25mg/kg and 75mg/kg while its latency was reduced at 25mg/kg and 50mg/kg. Interestingly SPs had a reduced latency of TCSs compared to APs at 75mg/kg. Glutamatergic and Gabaergic cell count was conducted to determine an association with the epileptic response to PTZ. The Glutamatergic cell counts for SPs was significantly greater than APs and conversely the Gabaergic cell counts in APs was higher compared to SPs. The reason for this difference in findings needs to be further investigated. This study shows that birds, and APs and SPs in particular, are a valid, interesting and under-explored model of epilepsy that should be further explored in order to understand the mysteries of epilepsy.

Reflex epileptic mechanisms in humans: Lessons about natural ictogenesis

The definition of reflex epileptic seizures is that specific seizure types can be triggered by certain sensory or cognitive stimuli. Simple triggers are sensory (most often visual, more rarely tactile or proprioceptive; simple audiogenic triggers in humans are practically nonexistent) and act within seconds, whereas complex triggers like praxis, reading and talking, and music are mostly cognitive and work within minutes. The constant relation between a qualitatively, often even quantitatively, well-defined stimulus and a specific epileptic response provides unique possibilities to investigate seizure generation in natural human epilepsies. For several reflex epileptic mechanisms (REMs), this has been done. Reflex epileptic mechanisms have been reported less often in focal lesional epilepsies than in idiopathic "generalized" epilepsies (IGEs) which are primarily genetically determined. The key syndrome of IGE is juvenile myoclonic epilepsy (JME), where more than half of the patients present reflex epileptic traits (photosensitivity, eye closure sensitivity, praxis induction, and language-induced orofacial reflex myocloni). Findings with multimodal investigations of cerebral function concur to indicate that ictogenic mechanisms in IGEs largely (ab)use preexisting functional anatomic networks (CNS subsystems) normally serving highly complex physiological functions (e.g., deliberate complex actions and linguistic communication) which supports the concept of system epilepsy. Whereas REMs in IGEs, thus, are primarily function-related, in focal epilepsies, they are primarily localization-related. This article is part of a Special Issue entitled "Genetic and Reflex Epilepsies, Audiogenic Seizures and Strains: From Experimental Models to the Clinic".

Dopaminergic medication unrelated myoclonus is less related to tremor in idiopathic Parkinson's disease

Myoclonus in Parkinson's disease (PD) may be related or unrelated to dopaminergic medication and may share some features of cortical myoclonus. The aim of this study was to analyze clinical and electrophysiological correlates of the dopaminergic treatment unrelated myoclonus in PD patients. We included 17 PD patients with the end-of-dose myoclonus and 16 PD patients without myoclonus between January 2010 and June 2011. Surface electromyography of upper extremity muscles and long latency reflexes (LLRs) were performed. Positive or negative myoclonus with a duration of 35-100 ms was observed. Rest tremor was less frequent in the group with myoclonus. Only one PD patient with myoclonus had C reflex. Mean LLR amplitude was significantly high in PD with myoclonus compared to the group without myoclonus (p = 0.024). Dopaminergic treatment unrelated myoclonus is less related to rest tremor in PD, may be positive or negative, and exhibits similar features to cortical myoclonus.

A Myoclonic Reaction with Low-Dose Hydromorphone

Objective:

To report a case of myoclonus associated with the use of a low dose of the opioid analgesic hydromorphone.

Case Summary:

A 55-year-old white man with a history of nonobstructive hypertrophic cardiomyopathy was hospitalized for treatment of severe chest pain. On hospital day 1, intravenous hydromorphone (6 doses, total dose of 4 mg) was administered. The pain continued and, on day 2, the dose was increased, with a total of 6 mg administered on day 2. The patient developed uncontrollable jerking movements of the head, neck, arms, and legs after he received the hydromorphone. The myoclonic movements stopped within a few hours following discontinuation of hydromorphone and did not recur.

Discussion:

Myoclonus is a neuroexcitatory symptom that has been reported with chronic, high-dose administration of hydromorphone in patients with impaired renal function. The hydromorphone-3-glucuronide metabolite is devoid of analgesic activity and has been shown to cause neuroexcitatory effects. This patient's symptoms appeared soon after hydromorphone was initiated and resolved in a timely manner after the medication was discontinued. Based on the patient's presentation and course of therapy, it is probable, as indicated by the Naranjo probability scale, that the myoclonic symptoms were induced by hydromorphone. This case was unique, however, in that the patient received hydromorphone for only a short duration and did not have impaired renal function.

Conclusions:

Neuroexcitatory effects of hydromorphone may occur at relatively low doses in patients without renal dysfunction. Early recognition and intervention are required to achieve resolution of these symptoms and prevent further sequelae to the patient.

Radiofrequency Ablation in the Treatment of Idiopathic Bilateral Palatal Myoclonus: A New Indication

Objectives:

We tested the effect of radiofrequency ablation in the treatment of palatal myoclonus refractory to other therapeutic regimens.

Methods:

A 20-year-old patient who presented with palatal myoclonus and annoying rhythmic objective clicking noise was treated with a radiofrequency generator with topical and local anesthesia in an outpatient setting.

Results:

The clicking noise was abolished within 3 to 4 days of the radiofrequency ablation. The rhythmic, jerky movements of the soft palate were confirmed to be absent 2 weeks later with electromyographic studies. The patient has been symptom-free for 6 months, and no side effects have occurred.

Conclusions:

As a new indication, radiofrequency ablation may effectively abolish abnormal movements of the soft palate and relieve associated tinnitus.

Asterixis

Asterixis is a type of negative myoclonus characterized by irregular lapses of posture of various body parts. It is an uncommon but important sign in clinical neurology. Initially described as a "liver flap," its utility encompasses a galaxy of neurological and nonneurological situations. Asterixis has a rich history. Despite being described over 70 years ago, its exact pathogenesis remains unknown. Its significance as a tool for the evaluation and prognosis of encephalopathies has been suggested. This review presents its history, clinical implications and its significance.

[VOLTAGE-GATED CALCIUM CHANNELS: CLASSIFICATION AND PHARMACOLOGICAL PROPERTIES (PART I).]

Calcium influx though voltage-gated calcium channels mediate a huge amount of physiological events and cellular responses. Numerous scientific reports indicate that calcium channels are involved in synaptic transmission, neurotransmitter release, regulation of gene expression, cellular membrane voltage oscillations, pacemaker activity, secretion of specific substances from nerve and secretory cells, morphological differentiation, activation of calcium-dependent enzymes, etc. This review represents the modern classification, molecular structure, physiological and pharmacological properties of voltage-gated calcium channels expressed in mammalian cells.

Low frequency nonevolving generalized periodic epileptiform discharges and the borderland of hypoxic nonconvulsive status epilepticus in comatose patients after cardiac arrest

To explore the EEG boundary of nonconvulsive status epilepticus (NCSE) and the concept of "possible NCSE", we studied 14 consecutive patients with ≤ 2-Hz nonevolving periodic generalized epileptiform discharges (GPDs) in their first EEG after out of hospital cardiac arrest (OHCA). The pattern was associated with myoclonus in 11 patients. EG reactivity to antiseizure drugs (benzodiazepines and propofol), but without clinical improvement, was noted in 8 patients, satisfying the diagnostic criteria of "possible NCSE". Resolution of GPDs and emergence of physiological rhythms in follow-up EEGs and/or subsequent clinical improvement were noted in 6 of them, strongly suggesting that the initial slow nonevolving GPD pattern reflected NCSE significantly contributing to their coma. Background rhythms from 10 to 90% of the periods between GPDs were noted in 9 patients and appeared to correlate with reactivity of the GPD pattern to antiseizure drugs when 20% or more. Ten patients died, and four were discharged to longer care rehabilitation centers. Although based on few observations, preliminary evidence appears to indicate that in this context, nonevolving GPD frequencies as low as 0.8 Hz can reflect clinically significant NCSE and, therefore, warrant appropriate testing for possible reactivity. There is also some preliminary indication that background rhythms may be another important diagnostic and, perhaps, prognostic indicator, but this needs to be tested in large prospective studies. This article is part of a Special Issue entitled "Status Epilepticus".

Design and validation of a periodic leg movement detector

Periodic Limb Movements (PLMs) are episodic, involuntary movements caused by fairly specific muscle contractions that occur during sleep and can be scored during nocturnal polysomnography (NPSG). Because leg movements (LM) may be accompanied by an arousal or sleep fragmentation, a high PLM index (i.e. average number of PLMs per hour) may have an effect on an individual’s overall health and wellbeing. This study presents the design and validation of the Stanford PLM automatic detector (S-PLMAD), a robust, automated leg movement detector to score PLM. NPSG studies from adult participants of the Wisconsin Sleep Cohort (WSC, n = 1,073, 2000–2004) and successive Stanford Sleep Cohort (SSC) patients (n = 760, 1999–2007) undergoing baseline NPSG were used in the design and validation of this study. The scoring algorithm of the S-PLMAD was initially based on the 2007 American Association of Sleep Medicine clinical scoring rules. It was first tested against other published algorithms using manually scored LM in the WSC. Rules were then modified to accommodate baseline noise and electrocardiography interference and to better exclude LM adjacent to respiratory events. The S-PLMAD incorporates adaptive noise cancelling of cardiac interference and noise-floor adjustable detection thresholds, removes LM secondary to sleep disordered breathing within 5 sec of respiratory events, and is robust to transient artifacts. Furthermore, it provides PLM indices for sleep (PLMS) and wake plus periodicity index and other metrics. To validate the final S-PLMAD, experts visually scored 78 studies in normal sleepers and patients with restless legs syndrome, sleep disordered breathing, rapid eye movement sleep behavior disorder, narcolepsy-cataplexy, insomnia, and delayed sleep phase syndrome. PLM indices were highly correlated between expert, visually scored PLMS and automatic scorings (r² = 0.94 in WSC and r² = 0.94 in SSC). In conclusion, The S-PLMAD is a robust and high throughput PLM detector that functions well in controls and sleep disorder patients.

Subacute Sclerosing Panencephalitis Presenting with Unilateral Periodic Myoclonic Jerks

Background:

Subacute sclerosing panencephalitis (SSPE) is a rare complication of measles virus infection. The disease is characterized by behavioural abnormalities, intellectual deterioration, motor weakness, and generalized myoclonic jerks progressing to coma and death in one to two years in 80% of the cases. The myoclonic jerks are associated with characteristic generalized slow periodic complexes on electroencephalography (EEG). The symptoms and signs of SSPE are frequently quite variable. The clinical course is equally variable and difficult to predict. The characteristic periodic myoclonus can rarely occur unilaterally particularly in the early stages of the disease. As well, the periodic EEG complexes have been reported unilaterally in up to 3% of cases.

Case Report:

A 12-year-old boy, who was seen at a later stage with atypical manifestation of myoclonic body jerks confined entirely unilaterally, combined with contralateral periodic EEG complexes. One could assume clinically that the more diseased hemisphere was responsible for generating the jerks. However, brain magnetic resonance imaging revealed asymmetric hemispheric changes suggesting that the less neurologically damaged hemisphere is responsible for generating the unilateral myoclonic jerks. This has led to the interpretation that the more severely damaged hemisphere has lost the neuronal connectivity required to generate these periodic myoclonic jerks.

Conclusion:

Subacute sclerosing panencephalitis may have asymmetric hemispheric involvement, not only early, but also in the advanced stages of the disease, which can result in unilateral periodic myoclonic jerks.

A Case of Familial Creutzfeldt-Jakob Disease Presenting with Dry Cough

Background:

Clinical diagnosis of Creutzfeldt-Jakob disease (CJD) is based on the classical triad of rapidly progressive dementia, myoclonus and abnormal EEG. The 200k mutation within the gene encoding PrP, located on the short arm of chromosome 20, accounts for more than 70% of families with CJD worldwide.

Case Report:

Herein, we report a patient who developed persistent dry cough and classical signs of CJD, including severe cognitive decline, cerebellar signs, and myoclonic jerks, leading to death a few weeks after disease onset. Mutation screening showed that he had the 200k point mutation in the PRNP gene. His mother had died twenty years earlier with neuropathologically confirmed CJD. She had presented a rapidly progressive ataxia with myoclonus, dementia, visual hallucinations, and the same persistent dry cough.

Conclusions:

The clinical presentation of this familial CJD case with persistent dry cough is quite unusual. Therefore, a neurological etiology should be sought when confronted with an unexplained persistent cough.

Clinical neurophysiology of psychogenic movement disorders: how to diagnose psychogenic tremor and myoclonus

Tremor and myoclonus are very common manifestations of psychogenic movement disorders (PMD). In this context, recording of movement disorders aims to provide objective criteria for a positive diagnosis of PMD, independently of the psychological situation. Neurophysiological observations are therefore considered to have a huge impact both on diagnosis and on therapeutic approaches. A specific recording strategy should be employed whenever the medical history or clinical clues raise the eventuality of a PMD. Polymyography coupled to accelerometry is used to demonstrate the major electrophysiological criteria of psychogenic tremor, namely spontaneous variability of tremor frequency and frequency entrainment induced by contralateral rhythmic tasks. Other features, such as paradoxical increase of tremor amplitude with mass loading, co-activation preceding tremor onset and alteration of voluntary contralateral motor performances when tremor is present, are also of interest. The clinical presentation of psychogenic myoclonus is extremely rich and polymorphous and can mimic virtually all forms of cortical, subcortical or spinal myoclonus. Focal, multifocal, axial or generalized jerks can occur. Psychogenic jerks can be sporadic or repetitive, rhythmic or arrhythmic, spontaneous or stimulus-induced. All of these parameters are crucial to determine an individualized neurophysiological strategy. Polymyography is critical to identify a ballistic pattern or a discordant or non-reproducible temporo-spatial organisation of the jerks, but has usually to be completed by other potentially decisive approaches. Reflex psychogenic myoclonus for example displays stimulus-response delays that are too long and variable. Spontaneous psychogenic jerks may be also preceded by a pre-movement potential, detectable by jerk-locked-back-averaging methods.

[Non-epileptic motor paroxysmal phenomena in wakefulness in childhood]

Paroxysmal events in childhood are a challenge for pediatric neurologists, given its highly heterogeneous clinical manifestations, often difficult to distinguish between phenomena of epileptic seizure or not. The non-epileptic paroxysmal episodes are neurological phenomena, with motor, sensory symptoms, and/or sensory impairments, with or without involvement of consciousness, epileptic phenomena unrelated, so no electroencephalographic correlative expression between or during episodes. From the clinical point of view can be classified into four groups: motor phenomena, syncope, migraine (and associated conditions) and acute psychiatric symptoms. In this paper we analyze paroxysmal motor phenomena in awake children, dividing them according to their clinical manifestations: extrapyramidal episodes (paroxysmal kinesiogenic, non kinesiogenic and not related to exercise dyskinesias, Dopa responsive dystonia) and similar symptoms of dystonia (Sandifer syndrome); manifestations of startle (hyperekplexia); episodic eye and head movements (benign paroxysmal tonic upward gaze nistagmus deviation); episodic ataxia (familial episodic ataxias, paroxysmal benign vertigo); stereotyped and phenomena of self-gratification; and myoclonic events (benign myoclonus of early infancy). The detection of these syndromes will, in many cases, allow an adequate genetic counseling, initiate a specific treatment and avoid unnecessary additional studies. Molecular studies have demonstrated a real relationship between epileptic and non-epileptic basis of many of these entities and surely the identification of the molecular basis and understanding of the pathophysiological mechanisms in many of them allow us, in the near future will benefit our patients.

[A one-year-old male infant with sleep-associated febrile myoclonus]

Febrile myoclonus is a benign neurological symptom induced by fever. The physiological mechanism is unknown. We herein report a 1 year and 7 months old male patient with intermittent jerks of the whole body during a high fever caused by acute otitis media. He experienced more than 50 jerks over a period of 2 days. The jerks appeared only during sleep. He showed no impairment of consciousness and no abnormalities in neurological examination, blood examination, electroencephalogram, or brain MRI findings. We diagnosed him with febrile myoclonus. The myoclonic jerks disappeared as the fever decreased without neurological sequelae. To the best of our knowledge, febrile myoclonus only during sleep has never been reported. To clarify the pathophysiology of febrile myoclonus, we should focus on the relationship between the myoclonus and the sleep/awake states.

Focal cortical myoclonus in rolandic cortical dysplasia presenting as hemifacial twitching

A 2-year-old girl presented with brief episodes of left hemifacial twitching. On ictal electroencephalography, repetitive focal spike discharges appeared at the right fronto-centro-temporal regions; these discharges preceded the onset of each twitch by 12 ms. Magnetic resonance imaging showed a linear abnormal signal intensity in the subcortical white matter at the right postcentral gyrus, where a cluster of dipole sources was detected by magnetoencephalography. These findings suggested that the patient had focal cortical myoclonus due to rolandic focal cortical dysplasia.

[Clinical and electroencephalographic characteristics of Jeavons syndrome]

OBJECTIVE

The study was designed to examine the clinical and electroencephalographic characteristics of children with Jeavons syndrome.

METHOD

Video-electroencephalography (VEEG) monitoring was carried out in 9 patients with Jeavons syndrome. The clinical and electroencephalographic characteristics, treatment and prognoses were analyzed.

RESULT

Of the 9 patients, 8 were female, and 1 was male. The onset age of children with eyelid myoclonia (EM) was from 3 to 9 years old. It was obtained through the chief complaint, prosecution or VEEG monitoring. Three cases were misdiagnosed and 2 cases were overlooked initially. Seven out of 9 patients had generalized tonic clonic seizures (GTCS) during the course of disease, of whom 5 experienced only one episode. GTCS was the cause for the first visits to hospital in 5 patients. Since the clinical manifestations of EM with or without absence were often slight, VEEG monitoring with eye closure and intermittent photic stimulation tests helped to induce discharges and seizures. Eye closure was more potent than intermittent photic stimulation as a triggering factor. Ictal EEG showed 3 - 6 Hz generalized spike and waves and polyspikes burst. The main treatment option was valproate monotherapy (6 cases) or combined with other antiepileptic drugs (1 case). Levetiracetam, lamotrigine and topiramate were also used in patients and effective to some degree. Two patients lost follow up. The age of 7 patients at follow-up ranged from 9 y to 15 y. Seizures were controlled in 1 case, suspiciously controlled in 1 case, decreased in frequency in 4 cases and were still frequent in 1 case. During follow-up, normal intelligence was found in the former 2 cases, difficult learning in 2 cases, and slightly intellectual impairment in 2 cases.

CONCLUSION

Jeavons syndrome is one of the idiopathic generalized epilepsies characterized by EM with or without absence. The age of seizure onset might be difficult to be exactly established, as EM was often misinterpreted and overlooked initially. Clinical history combined with VEEG monitoring with eye closure and intermittent photic stimulation tests could diagnose this disease. Valproate and other new antiepileptic drugs were effective for this disease. Jeavons syndrome is a lifelong disorder. Seizures sometimes could be well controlled. When seizures were resistant to treatment, cognitive and intellectual impairment might occur.

[Video electroencephalographic diagnosis of epileptic and non-epileptic paroxysmal episodes in infants and children at the pre-school age]

The main usefulness of video electroencephalographic (video-EEG) monitoring lies in the fact that it allows proper classification of the type of epileptic seizure and epileptic syndrome, identification of minor seizures, location of the epileptogenic zone and differentiation between epileptic seizures and non-epileptic paroxysmal manifestations (NEPM). In infants and pre-school age children, the clinical signs with which epileptic seizures are expressed differ to those of older children, seizures with bilateral motor signs such as epileptic spasms, tonic and myoclonic seizures predominate, and seizures with interruption of activity or hypomotor seizures, and no prominent automatisms are observed. In children with focal epilepsies, focal and generalised signs are often superposed, both clinically and in the EEG. NEPM may be benign transitory disorders or they can be episodic symptoms of different neurological or psychopathological disorders. NEPM are often observed in children with mental retardation, neurological compromise or autism spectrum disorders, who present epileptic seizures and epileptiform abnormalities in the baseline EEG. It then becomes necessary to determine which episodes correspond to epileptic seizures and which do not. The NEPM that are most frequently registered in the video-EEG in infants and pre-school age children are unexpected sudden motor contractions ('spasms'), introspective tendencies, motor stereotypic movements and paroxysmal sleep disorders.

Automatic analysis of EMG during clonus

Clonus can disrupt daily activities after spinal cord injury. Here an algorithm was developed to automatically detect contractions during clonus in 24h electromyographic (EMG) records. Filters were created by non-linearly scaling a Mother (Morlet) wavelet to envelope the EMG using different frequency bands. The envelope for the intermediate band followed the EMG best (74.8-193.9 Hz). Threshold and time constraints were used to reduce the envelope peaks to one per contraction. Energy in the EMG was measured 50 ms either side of each envelope (contraction) peak. Energy values at 5% and 95% maximal defined EMG start and end time, respectively. The algorithm was as good as a person at identifying contractions during clonus (p=0.946, n=31 spasms, 7 subjects with cervical spinal cord injury), and marking start and end times to determine clonus frequency (intra class correlation coefficient, α: 0.949), contraction intensity using root mean square EMG (α: 0.997) and EMG duration (α: 0.852). On average the algorithm was 574 times faster than manual analysis performed independently by two people (p ≤ 0.001). This algorithm is an important tool for characterization of clonus in long-term EMG records.

[Myoclonus in children]

The article includes data on terminology, an etiology, mechanism and clinical presentation of myoclonus in children. The clinical classification, scheme of diagnostic search and feature of the differential diagnosis of different types of myoclonus is presented.

Radicular myoclonus in a patient with Guillain-Barré Syndrome

A 53-year-old Japanese woman presented with myoclonus during the course of Guillain-Barré syndrome. The myoclonus was characterized by relatively regular involuntary movements, starting from proximal muscles of the right lower leg, and moving almost simultaneously towards the left lower leg and upper trunk. Surface electromyography revealed rhythmic synchronous discharges with 100-200 ms duration in the agonist and antagonist muscles at approximately 4 Hz. The jerk-locked back averaging, long latency reflexes, and somatosensory evoked potentials studies were normal. We report myoclonus due to radiculitis in a patient with Guillain-Barré syndrome.

Spinal segmental myoclonus during postural maintenance in a patient with cervical spondylosis: a case report

Spinal segmental myoclonus is defined as a rare involuntary movement characterized by myoclonic jerks of spinal origin. We describe the case of a 62-year-old woman who developed spinal segmental myoclonus 4 months after undergoing cervical laminoplasty for ossification of the posterior longitudinal ligament. Myoclonic jerks were observed in the upper trapezius innervated by C3-4, which corresponded to the level of myelomalacia. These jerks were elicited and aggravated in the sitting and standing positions but were completely suppressed in the supine position. The myoclonus was refractory to medication but improved with the use of a soft neck brace.

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.

Ankle clonus and its relationship with the medium-latency reflex response of the soleus by peroneal nerve stimulation

Ankle clonus and soleus medium-latency reflex are stretch-induced responses. Clonus is traditionally considered to be the result of oscillation in the group Ia mediated spinal stretch reflex but the soleus medium-latency reflex response originates mainly from the activation of group II afferents. The medium latency reflex response (MLR) was recorded in soleus muscle by peroneal nerve stimulation and clonus beats were recorded in soleus muscle using EMG in 19 spastic patients. The dorsiflexion (DF) and plantarflexion (PF) times of clonus and the half-period were calculated based on accelerometric measurements in 11 patients. The MLR of the soleus was 73.63 ± 8.9 ms. The half-period of the clonus was 79.34 ± 12.31 ms. The difference between the MLR and half-period was significant. The PF was 71.75 ± 6.73 ms, and the DF was 88.63 ± 10.83 ms. The difference between the soleus MLR and PF part of the clonus beat was not significant. The PF part of the clonus beat is due to soleus muscle contraction and controlled by the neural part of the oscillation. There may be relationship between the soleus MLR and the PF part of the clonus. Clonus is considered to be the result of oscillations in the group Ia spinal stretch reflex, but there is sufficient time for group II afferents to be involved.