Treatment of palatal myoclonus with sumatriptan

Myoclonus- A Review

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

Palatal Tremor - Pathophysiology, Clinical Features, Investigations, Management and Future Challenges

Background:

Palatal tremor is involuntary, rhythmic and oscillatory movement of the soft palate. Palatal tremor can be classified into three subtypes; essential, symptomatic and palatal tremor associated with progressive ataxia.

Methods:

A thorough Pubmed search was conducted to look for the original articles, reviews, letters to editor, case reports, and teaching neuroimages, with the keywords “essential”, “symptomatic palatal tremor”, “myoclonus”, “ataxia”, “hypertrophic”, “olivary” and “degeneration”.

Results:

Essential palatal tremor is due to contraction of the tensor veli palatini muscle, supplied by the 5^th cranial nerve. Symptomatic palatal tremor occurs due to the contraction of the levator veli palatini muscle, supplied by the 9%^th and 10%^th cranial nerves. Essential palatal tremor is idiopathic, while symptomatic palatal tremor occurs due to infarction, bleed or tumor within the Guillain-Mollaret triangle. Progressive ataxia and palatal tremor can be familial or idiopathic. Symptomatic palatal tremor and sporadic progressive ataxia with palatal tremor show signal changes in inferior olive of medulla in magnetic resonance imaging. The treatment options available for essential palatal tremor are clonazepam, lamotrigine, sodium valproate, flunarizine and botulinum toxin. The treatment of symptomatic palatal tremor involves the treatment of the underlying cause.

Discussion:

Further studies are required to understand the cause and pathophysiology of Essential palatal tremor and progressive ataxia and palatal tremor. Similarly, the link between tauopathy and palatal tremor associated progressive ataxia needs to be explored further. Oscillopsia and progressive ataxia are more debilitating than palatal tremor and needs new treatment approaches.

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 Update on Myoclonus Management

INTRODUCTION

Myoclonus is a hyperkinetic movement disorder characterized by sudden, brief, lightning-like involuntary jerks. There are many possible causes of myoclonus and both the etiology and characteristics of the myoclonus are important in securing the diagnosis and treatment. Myoclonus may be challenging to treat, as it frequently requires multiple medications for acceptable results. Few randomized controlled trials investigating the optimal treatment for myoclonus are available, and expert experience and case series guide treatment. Areas Covered: In this article, the authors review the basics of myoclonus and its classification. The authors discuss the current management of myoclonus and then focus on recent updates in the literature, including both pharmacologic and surgical options. Expert opinion: Myoclonus remains a challenge to manage, and there is a paucity of rigorous clinical trials guiding treatment paradigms. Furthermore, due to the etiological heterogeneity of myoclonus, defining the appropriate scope for high-quality clinical trials is challenging. In order to advance the field, the myoclonus study group needs to be revived in the US and abroad so that interested investigators can collaborate on multicenter clinical trials for myoclonus treatments.

Hypertrophic olivary degeneration in children after posterior fossa surgery. An underdiagnosed condition

BACKGROUND

Hypertrophic olivary degeneration (HOD) is a rare transsynaptic form of degeneration occurring after injury to the dentato-rubro-olivary pathway ("Guillain-Mollaret triangle"). The majority of studies have described HOD resulting from posterior fossa (PF) hemorrhage or infarction. HOD in patients undergoing PF surgery has not been well characterized. These lesions are rare and symptomatic children with HOD are even more uncommon. The purpose of this study was to evaluate HOD that develops after PF operations in children.

MATERIALS AND METHODS

A literature review was carried out describing 37 pediatric cases of HOD in 13 articles. In addition, two new cases of our own experience were included.

CONCLUSIONS

HOD is a rare complication related after PF tumors surgery and symptoms may be misdiagnosed with pediatric cerebellar mutism syndrome. Children with HOD usually do not develop palatal tremor but ataxia is common.

Treatment of myoclonus

Myoclonus creates significant disability for patients. This symptom or sign can have many different etiologies, presentations, and pathophysiological mechanisms. A thorough evaluation for the myoclonus etiology is critical for developing a treatment strategy. The best etiological classification scheme is a modified version from that proposed by Marsden et al. in 1982. Clinical neurophysiology, as assessed by electromyography and electroencephalography, can be used to classify the pathophysiology of the myoclonus using a neurophysiology classification scheme. If the etiology of the myoclonus cannot be reversed or treated, then symptomatic treatment of the myoclonus itself may be warranted. Unfortunately, there are few controlled studies for myoclonus treatments. The treatment strategy for the myoclonus is best derived from the neurophysiology classification scheme categories: 1) cortical, 2) cortical-subcortical, 3) subcortical-nonsegmental, 4) segmental, and 5) peripheral. A cortical physiology classification is most common. Levetiracetam is suggested as first-line treatment for cortical myoclonus, but valproic acid and clonazepam are commonly used. Cortical-subcortical myoclonus is the physiology demonstrated by myoclonic seizures, such as in primary epileptic myoclonus (e.g., juvenile myoclonic epilepsy). Valproic acid has demonstrated efficacy in such epileptic syndromes with other medications providing an adjunctive role. Clonazepam is used for subcortical-nonsegmental myoclonus, but other treatments, depending on the syndrome, have been used for this physiological type of myoclonus. Segmental myoclonus is difficult to treat, but clonazepam and botulinum toxin are used. Botulinum toxin is used for focal examples of peripheral myoclonus. Myoclonus treatment is commonly not effective and/or limited by side effects.

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.

Palatal myoclonus: an unusual presentation

We describe a 16-year-old woman with an unusual clinical presentation of palatal myoclonus after a severe upper respiratory infection. Besides the postinfectious onset, this case is unique in that the rhythmical contractions of her oropharynx, larynx, and esophagus occur in couplets rather than single contractions of typical essential palatal myoclonus. Additionally, these contractions are present only during the inspiratory phase of respiration. Imaging and other diagnostic studies show no evidence of cerebellar or brainstem pathology. This case broadens the phenomenology of palatal myoclonus and illustrates the occasional overlap in clinical features between essential and symptomatic palatal myoclonus.

The 'essentials' of essential palatal tremor: a reappraisal of the nosology

Essential palatal tremor (EPT) is an uncommon disorder, distinct from symptomatic palatal tremor (SPT), but characterized by superficially similar rhythmic movements of the soft palate. While the pathophysiology of SPT has been relatively well defined, this is not the case in EPT. Based on an analysis of 103 published cases, we reviewed EPT in the context of other movement disorders with similar features and outline possible pathophysiological mechanisms. Phenomenologically it remains best classified as a tremor. Four major causes, including a central generator, peripheral/mechanical, voluntary/special skill and psychogenic, appear to account for the majority of cases of EPT, although there is considerable overlap in the pathogenic mechanisms underlying these categories. Among the cases reviewed, a large proportion fit into the latter two categories, although there are others where multiple mechanisms are likely at play. Based on our reappraisal, we suggest a change in designation to 'isolated palatal tremor', with primary and secondary subtypes. This retains the distinction from SPT and emphasizes the non-uniform, heterogeneous nature of the disorder.

Myoclonus: current concepts and recent advances

Myoclonus presents as a sudden brief jerk caused by involuntary muscle activity. An organisational framework is crucial for determining the medical significance of the myoclonus as well as for its treatment. Clinical presentations of myoclonus are divided into physiological, essential, epileptic, and symptomatic. Most causes of myoclonus are symptomatic and include posthypoxia, toxic-metabolic disorders, reactions to drugs, storage disease, and neurodegenerative disorders. The assessment of myoclonus includes an initial screening for those causes that are common or easily corrected. If needed, further testing may include clinical neurophysiological techniques, enzyme activities, tissue biopsy, and genetic testing. The motor cortex is the most commonly shown myoclonus source, but origins from subcortical areas, brainstem, spinal, and peripheral nervous system also occur. If treatment of the underlying disorder is not possible, treatment of symptoms is worthwhile, although limited by side-effects and a lack of controlled evidence.

[Palatal myoclonus and dysphagia]

INTRODUCTION

Post brainstem lesion dysphagia is frequently associated with palatal myoclonus (PM) but the correlation between these two symptoms is still unclear.

OBJECTIVE

The aim of this study was to verify the relationship between PM and dysphagia, and if PM could itself induce dysphagia.

PATIENTS AND METHODS

Twelve patients suffering from post brainstem lesion PM and dysphagia; 10 male and two female, mean aged of 50.5 years, were assessed using clinical examination, radiological and endoscopic examination of deglutition.

RESULTS

In three cases, PM were associated with pharyngeal area decreasing, laryngeal aspiration, and dysphagia.

DISCUSSION

This study confirms the hypothesis of close relationship between PM and dysphagia. In these cases, specific dysphagia therapy should be recommended.

CONCLUSION

Post brainstem lesion dysphagia is sometimes associated with PM and in some cases, there is probably a relationship between PM and swallowing disorders of these patients.

Migraine and the extrapyramidal system

This review explores a large series of observations from clinical and experimental studies on the interactions between migraine and the extrapyramidal system (EPS). A critical appraisal of these data suggests that the EPS is somehow involved in migraine. However, primary involvement of the EPS in the pathophysiology of migraine, as hinted at by the apparent concomitance of migraine, extrapyramidal symptoms and diseases, as well as by the common involvement of neurotransmitters and pathways, cannot as yet be proven. On the other hand, the involvement of EPS in migraine may reflect its more general role in the processing of nociceptive information and/or may be part of the complex behavioural adaptive response that characterizes migraine.

Myoclonus and its disorders

This article defines myoclonus, describes the numerous causes of myoclonus, and summarizes various classification schemes. The electrodiagnostic characteristics and pathophysiology of this movement disorder are described. Treatment of the various forms of myoclonus is also discussed.

Myoclonus

The diagnosis and treatment of myoclonus pose a particular challenge to the neurologist. Few well-controlled double-blind studies of antimyoclonic agents have been performed, and clinical rating of the effectiveness of treatment has been primarily descriptive. As a result, therapy is often empiric. This article reviews the author's approach to treating patients with myoclonus. Three principles guide treatment. First, the cause and physiology of the myoclonic jerks must be ascertained before choosing the appropriate therapy. Second, multiple drugs often must be used in combination to achieve functional improvement. Third, given the paucity of adequately controlled trials, the treating physician must rely on well-documented case series of patients with myoclonic syndromes who obtained benefit from a drug.