Movement disorders

1. Myoclonus
Dr. Sachin Adukia

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 2o 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

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

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

23. Part three

25. 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

26. 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).

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

28. 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.

29. 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.

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

31. Thank You