myoclonus.pptx.............................

myoclonus

1. Myoclonus Dr . Madhu S M

2. Myoclonus is a clinical sign that is characterized by brief, shocklike , involuntary movements caused by muscular contractions or inhibitions [1]. Muscular contractions produce positive myoclonus , muscular inhibitions produce negative myoclonus ( ie , asterixis ). Patients will usually describe myoclonus as consisting of "jerks," "shakes," or "spasms."

3. ANATOMIC AND PHYSIOLOGIC CLASSIFICATION classified by the localization of the physiologic mechanism that generates it Cortical Cortical- subcortical Subcortical-nonsegmental Segmental Peripheral

4. Cortical focal discharge from the primary sensorimotor cortex causes myoclonic jerk Occurs because of insufficient inhibition within neuronal circuits of the primary motor cortex, primary sensory cortex, or both Rapid generalization - can produce myoclonic seizures in certain epileptic syndromes may occur with reflex sensory stimulation (cortical reflex myoclonus ), Muscle activation (cortical action myoclonus ), with rest ( eg , focal motor seizure), or any combination

5. Cortical- subcortical involves abnormal, paroxysmal, and excessive oscillation in bidirectional connections between cortical and subcortical sites. is the major mechanism for myoclonic seizures in primary generalized epileptic syndromes (JME) and others ( eg , minipolymyoclonus ). Eg : in JME and absence epilepsy, thalamic networks abnormally couple with widespread cortical areas to produce excessive neuronal activity The resulting myoclonic jerks are commonly generalized or bisynchronous.

6. Subcortical-nonsegmental myoclonus is generated from a site that is subcortical , but myoclonus manifests far beyond segments that are near the originating site. Eg . reticular-reflex myoclonus and propriospinal abnormal activity begins in a focal area of neuraxis and then spreads in both rostral and caudal directions, producing generalized myoclonus

7. Segmental myoclonus generated at a particular segment or contiguous segments of brainstem and/or spinal cord. Freq. of motor oscillations < tremor. manifests at, or close to, that particular segment or contiguous segments of the body palatal myoclonus spinal segmental myoclonus

8. Peripheral myoclonus arises d/t peripheral nervous system lesion produces hyperactive motor discharges to its muscle ( eg , hemifacial spasm).

9. Anatomic and physiologic classification

10. CLINICAL AND ETIOLOGIC CLASSIFICATION classification scheme of Marsden and colleagues ● Physiologic ● Essential ● Epileptic ● Secondary (symptomatic)

11. Physiological: Jerks associated with sleep occur during sleep or sleep transitions Partial myoclonic jerks – multifocal, s/ i distal muscles Massive myoclonic jerks – hypnic - gen., affect trunk and proximal muscles Periodic movements of sleep (nocturnal myoclonus ) are stereotyped repetitive dorsiflexion of toes and feet, sometimes with flexion of knees and hips

12. Essential myoclonus - divided into sporadic and hereditary myoclonus is the most prominent or only clinical finding - ie , an "essential" phenomenon Sporadic (or idiopathic) essential myoclonus - heterogeneous w.r.t . distribution, exacerbating factors, CNS findings Palatal myoclonus often 2 o to brainstem and/or cerebellar lesion. However, some patients have no apparent structural lesion - essential palatal myoclonus . myoclonus is c/b contractions of the tensor veli palatini secondary (symptomatic) c/b contractions of levator veli palatini .

13. Hereditary essential myoclonus demonstrates a subcortical-nonsegmental physiology Clinical features Onset < 20 yrs AD benign course - active life and normal lifespan Absence of cerebellar ataxia, spasticity, dementia, and seizures occurs throughout arms & axial muscles. exacerbated by muscle activation markedly diminished with alcohol ingestion.

14. Epileptic myoclonus Is myoclonus in the setting of epilepsy cortical or cortical- subcortical physiology Seizures dominate the clinical picture idiopathic, genetic, or a static encephalopathy Myoclonus can occur as one of several components of a seizure the only seizure manifestation - myoclonic seizure one of multiple seizure types within an epileptic syndrome

15. Familial cortical myoclonic tremor with epilepsy Autosomal dominant inheritance Adult onset Distal action tremor and myoclonus Infrequent, 2 o GTCS Relatively benign course, typically normal cognition Responsiveness to anticonvulsants

16. Symptomatic (secondary) myoclonus occurs as a secondary symptom of neurologic or non-neurologic disorder

17. Part three

18. Treatment to control myoclonus - treat the underlying disorder may reverse certain myoclonus myoclonus caused by an acquired abnormal metabolic state medication or toxin excisable lesion psychogenic etiology Evidence base for treatment is mainly of observational case series and case reports

19. Cortical myoclonus Drug treatment – aim is to augment inhibitory processes within sensorimotor cortex Levetiracetam , piracetam - initial drugs clonazepam and valproic acid – add on’s Gait disturbance - most resistant to treatment. An unsteady gait with frequent falls may persist despite control of action and reflex myoclonus in UL Also, there is no consistent evidence for benefit in negative myoclonus ( asterixis ).

20. Cortical- subcortical myoclonus Includes the myoclonus in PGE Treatment is that of epilepsy

21. Subcortical-nonsegmental myoclonus Standard antiepileptic treatments- not helpful In addition, increased risk of alcoholism in patients with essential myoclonus (including myoclonus-dystonia ) because condition is ethanol-responsive. initial treatment with clonazepam Benztropine or trihexyphenidyl – alternatives for initial or add-on therapy in essential myoclonus , including myoclonus-dystonia Zonisamide - propriospinal myoclonus .

22. Segmental myoclonus Spinal Myoclonus clonazepam (up to 6 mg daily) However, benefit - limited. Alternatives- levetiracetam , botulinum toxin injection, carbamazepine , diazepam, and tetrabenazine . Palatal myoclonus – botulinum toxin injections as initial treatment for debilitating palatal myoclonus pharmacologic interventions- no benefit possibly useful drugs : clonazepam , piracetam , valproic acid, baclofen , carbamazepine , lamotrigine , phenytoin , sumatriptan , and tetrabenazine .

23. Peripheral myoclonus botulinum toxin injection hemifacial spasm and other peripheral myoclonus carbamazepine may have some effect.

24. Thank You