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Myoclonus
- 1. MYOCLONUS Dr PS Deb MD, DM Director Neurology GNRC Hospitals , Guwahati, Assam, India
- 2. MYOCLONUS Definition Sudden shock like contraction of muscle. Flexor of upper limb and extensor of lower limb Varying in severity from insufficient to move the joints to fall in ground Sensory stimulation aggravate attack. EMG Burst of 30-60 ms synchronous Burst of 75-125 ms asynchronous Burst of >150 ms synchronous C-reflex – Stimulation of nerve → time locked response. EEG Variable pattern Time lag with EMG activity before or after Back averaging required
- 3. FOCAL MYOCLONUS Rhythmic, unchanged by rest, action, sleep, walking due to generation of discharge from discrete segment of neuraxis. Segmental myoclonus when segment of neuraxis involved. Arrhythmic. Spontaneous / Action / intentional / reflex Cortical Usually multifocal Distal > proximal, flexor > extensor Intentional or reflex , may be modality specific
- 4. EPILEPSIA PARTIALIS CONTINUA Rhythmic form, Group of muscles – face, arm or leg, persist for months Etiology – vascular, trauma, infection, MS, tumor EMG: Burst of agonist muscles, synchronous with antagonistic muscle EEG – Focal positive negative transient over sensory- motor cortex contralateral to the jerk, time locked 20sec. C-Reflex – correlated with giant somato-sensory evoked potential Evoked potential – large component of P1N2 has some relation to C-reflex as the positive negative transient to the spontaneous jerk Cranial nerve involvement cephalocaudal
- 5. CORTICAL MYOCLONUS Mechanism Hyper excitability of the sensory-motor cortex → large synchronous discharge → muscle jerk Paroxysmal depolarization shift (fragment of epilepsy) Cause Any focal cortical damage Tumor, Angioma Encephalitis Idiopathic Treatment Surgical removal of the cause Anticonvulsant
- 6. BRAINSTEM MYOCLONUS: PALATAL MYOCLONUS Clinical Rhythmic oscillation of palate sometime other part (ocular, tongue, larynx, pharynx, diaphragm) Brachial muscles are affected related to rhythmicity of respiration/gill movement Persist during sleep -1.5-3Hz Mechanism: Tegmental tract lesion → Inf. Olive oscillate → Purkunji cell → Reticulospinal tract / vestibulospinal tract Any lesion of Gullain Mollaret Triangle – Dentate – Red nucleus – Inf. Olive Pathology Hypertrophic degeneration of inf. Olive.
- 7. PALATAL MYOCLONUS CONT… Cause Idiopathic Stroke Trauma Tumor → 10months later Metabolic encephalopathy Prognosis: Resistant Treatment Tetrabenazine Halloparidol 5-Hydroxytryptophan Carbamazipine Bulbar myoclonus: Tongue and neck movement
- 8. SPINAL MYOCLONUS Clinical Rhythmic > arrhythmic Spontaneous, persist in sleep One limb, adjacent trunk or both legs Cause Degenerative Demylination C. myelopathy Tumor, Following spinal anesthesia Contrast injection Rarely idiopathic Ischemic myelopathy : stimulus sensitive myoclonus Rx: Clonazepam
- 9. PERIPHERAL MYOCLONUS Rarely true myoclonus is seen with acute or chronic denervation in involved muscle Lesion: Nerve Brachial plexus Nerve root Essential – rarely focal Treatment: Clonazepam
- 10. MULTIFOCAL OR GENERALIZED (EPILEPTIC MYOCLONUS) Types Multifocal : focal jerks at different part of body Generalized: Large part of body affected Etiology may be same Cortical: Increased excitability of brain due to paroxysmal depolarization shift involving group of neuron in different part of brain – Fragment of epilepsy EEG shows typical multifocal discharge and cortical correlation SSEP - ↑
- 11. RETICULAR – GENERALIZED Clinical Proximal more than distal Flexor more than extensor Sometime segment of body all muscle Spontaneous or reflex or action Cranial muscle → caudo-cephalic involvement Mechanism Hyper-excitability of a portion of the caudal brain stem reticular formation – the nucleus reticularis gigentocellularis EEG: Spike, generalized highest amplitude vertex Follow the EMG burst of myoclonus Spike is not time locked to the myoclonus, spike is projected and not directly responsible for myoclonus SEP is not enhance (no cortical hyperactivity) Combined Reticular and Cortical myoclonus due to combined lesion
- 12. PRIMARY GENERALIZED EPILEPTIC MYOCLONUS Focal Commonly small focal movement with finger movement (minipolymyoclonus also seen with peripheral denervation) Generalized Synchronized whole body jerk (fragment of gen. epilepsy) Cranial muscle activation down the brain stem Mechanism Whole cortex is hyper excitable and is driven to a paroxysm by normal ascending impulse from the brain stem reticular formation and non specific thalamic nuclei. Ascending impulse could be paroxysmal EEG: Generalized fronto central predominance, slow negativity which precedes the myoclonus For small jerk this event last 100-250 ms and jitter in time with respect to jerk
- 13. PROGRESSIVE MYOCLONIC EPILEPSY Nonspecific, various condition with progressive multifocal or generalized epilepsy ± dementia 1. Spinocerebellar Degeneration Clinical Heterogenous syndrome (Prototype : Mitochondrial myopathy, Hexose aminidase A deficiency) Progressive myoclonus Reflex + action Generalized epilepsy Cerebellar ataxia Sporadic or AR Onset 5-15 years Occasional associated Dementia Spasticity Myopathy Neuropathy Deafness
- 14. SPINOCEREBELLAR DEGENERATION CONT.. History Unverricht – Familial myoclonic epilepsy (first described) Lundborg – one case cerebellar degeneration Ramsay Hunt – Dessenrgia cerebellomyoclonica Pathology : Fridrich ataxia + dentate degeneration Baltic myoclonus Scandinavian – Koskiniemi American – Eldrige Treatment Valproate Clonazepam Phenobarbital Phenytoin aggravates
- 15. STORAGE DISORDER 1. Cerebellar with Dementia 1. Lafora body disease 2. GM2 gangliosidosis ( Hex A) 3. Ceroid lipofuscinosis (Batter’s disease 4. Sialidosis (Chery red spot) 5. Goucher 6. Mitochondrial myopathy 2. Extrapyramidal + 1. Wilson’s disease 2. Hallevorden Saptz disease 3. Torsion dystonia 4. PSP 5. Huntington disease 6. Biotin deficiency
- 16. 3. Dementia 1. Crutzfield Jakob disease 2. Alzheimer’s disease 4. Viral encephalopathy 1. Herpes simplex encephalitis 2. Subacute sclerosing pan encephalitis 5. Metabolic 1. Hepatic 2. Renal 3. Hyponatremia 4. Hypoglycemia 5. Non ketotic hyperglycemia
- 17. 6. Toxic 1. Bismuth 2. Heavy metal 3. Methyl bromide 4. Drugs 7. Physical 1. Trauma 2. Heat 3. Electric shock 4. Decompressive sickness 5. Hypoxia –
- 18. LANCE ADAM SYNDROME Clinical Post hypoxic action + intension myoclonus Cerebellar ataxia Gait disturbance Grand mal seizure Mechanism Reticular loop reflex Cortical reflex mechanism CSF – 5 Hydroxyindoeacitic acid ↓ → 5HT disturbance Treatment 5HT + Carbidopa Clonazepam + Valproate Carbamazepine Levodopa Estrogen Piracetam
- 19. ESSENTIAL MYOCLONUS - Friedrich – Paramyoclonus multiplex Myoclonus without seizure, dementia, ataxia Multifocal or generalized variable magnitude May present at rest movement or action No reflex myoclonus EEG and other lab test should be normal Familial or sporadic AD, M:F equal Onset – 1st to 2nd decade Korten 1974 in a family Essential myoclonus + tremor Other member tremor Both relieved by alcohol Some cases have dystonia Balastic movement overflow myoclonus Treatement: 5HT, VAL, CLZ, Alcohol
- 20. CHILDHOOD MYOCLONIC EPILEPSIES Infantile Myoclonus: West syndrome Benign myoclonic epilepsy of infancy 3-8 months onset Repetitive flexor spasm No mental disturbance Self limiting Lanox Gastaut syndrome True myoclonic epilepsy – symptomatic / cryptogenic Late Childhood / adolescent – Myoclonic with absence Myoclonic epilepsy of adolescent
- 21. OSCILLATORY MYOCLONUS Burst of myoclonic jerk which tend to wane in amplitude Once started in part of the body the movement may spread to other part and gradually wane No other abnormality Obeso described anoxic injury
- 22. STARTLE SYNDROME Clinical Sudden muscular contraction to surprise stimuli Onset when start walking Exaggerated startle → stiffness of body may → fall ± shout Prominent hypnogogic ± diurnal generalized myoclonic jerks Hesitant broad based gait May improve or persist in later life EMG response are shorter than normal latency EEG – Abrupt onset of spike and slow wave complex maximum from centrally → background dysynchronization → normal SSEP – significant increased amplitude Hyperactive long latency reflex due to dys-inhibition of certain brainstem center May be stimulus sensitive myoclonic disorder
- 23. STARTLE EPILEPSY Non habituating startle → tonic extensor spasm → epilepsy ± EEG – Desynchornization → frank epileptiform discharge bilaterally symmetrical or even focal Jumping/ Latah/ Myriachit – Initial violent startle in response to sudden unexpected sensory stimulation → echolalia, echopraxia, coprolalia or the assumption of defensive posture
- 24. NOCTURNAL MYOCLONUS Physiological Familial nocturnal start Occur at sleep onset Gross, generalized body jerk → arousal Physiological fragmentary myoclonus Small fragmentary jerk of head face or diffuse REM sleep or drowsiness Benign neonatal sleep myoclonus During all stages of sleep Lack EEG correlation No neurological abnormality
- 25. NOCTURNAL MYOCLONUS Pathological Periodic movement in sleep EEG burst of 200-500ms more than myoclonus Common in flexor muscle Periodic 20-30 sec Two side of the body can be activated independently Simultaneously or alternating during NREM sleep or drowsiness Normally asymptomatic Baclofen reduces amplitude
- 26. SLEEP RELATED MOVEMENT DISORDER Restless leg syndrome Intense feeling of paresthesia or funny feeling in leg → desire to move → improve May be associated with peripheral neuropathy or familial May be associated with myoclonus or PMS Clonazepam Excessive fragmentary myoclonus in NREM sleep > 50 jerks/ min for 20 consecutive NREM Associated with other disorder and PMS
- 27. THANKS