For further information, see CMDT Part 24-14: Movement Disorders
Myoclonic jerks are sudden, shock-like muscle contractions
Occasional myoclonic jerks may occur in anyone, especially when drifting into sleep
General or multifocal myoclonus: common in patients with idiopathic epilepsy and certain hereditary disorders
Generalized myoclonic jerking may
Accompany uremic and metabolic encephalopathies
Result from therapy with levodopa or cyclic antidepressants
Occur in alcohol or drug withdrawal states
Follow anoxic brain damage
It is common in subacute sclerosing panencephalitis and Creutzfeldt-Jakob disease
Myoclonus may respond to
Anticonvulsant drugs, especially valproic acid or levetiracetam
Benzodiazepines, particularly clonazepam (Table 24–2)
Piracetam (up to 16.8 g daily; not available in United States)
Myoclonus after anoxic brain damage may respond to
In patients with segmental myoclonus, a localized lesion (spinal or cerebral) should be searched for and treated appropriately
Table Graphic Jump Location Table 24–2.Medication treatment for seizures in adults (in alphabetical order within classes). ||Download (.pdf) Table 24–2. Medication treatment for seizures in adults (in alphabetical order within classes).
|Medication ||Usual Adult Daily Oral Dose ||Minimum No. of Daily Doses ||Time to Steady-State Medication Levels ||Optimal Medication Level and Laboratory Monitoring1 ||Selected Side Effects and Idiosyncratic Reactions |
|Generalized or Focal Seizures |
|Brivaracetam2,3 ||50–100 mg ||2 ||1–2 days ||CBC, liver biochemical tests ||Somnolence, fatigue, ataxia, vertigo, psychosis, leukopenia, hypersensitivity (bronchospasm and angioedema). |
|Cannabidiol4 ||5–20 mg/kg ||2 ||11–13 days ||Liver biochemical tests at baseline, 1, 3, and 6 months || |
Somnolence, fatigue, anorexia, weight loss, anemia, diarrhea, rash, sleep disorder, infections.
Elevation in liver enzymes may occur; reduce dose in hepatic impairment.
|Carbamazepine2 ||400–1600 mg (immediate or extended release) ||2 ||3–4 days || |
CBC, liver biochemical tests, BUN/Cr
Nystagmus, dysarthria, diplopia, ataxia, drowsiness, nausea, blood dyscrasias, hepatotoxicity, hyponatremia, Stevens-Johnson syndrome.5
May exacerbate myoclonic seizures.
|Cenobamate2,3 ||200–400 mg ||1 ||14 days ||Liver biochemical tests, potassium ||Multiorgan hypersensitivity, QT shortening, somnolence, dizziness, cognitive dysfunction, blurred vision. |
|Clobazam6 ||10–40 mg ||2 ||7–10 days || ||Lethargy and somnolence, ataxia, insomnia, dysarthria, aggression, constipation, fever, Stevens-Johnson syndrome. |
|Clorazepate3 ||22.5–90 mg ||2 ||10 days || ||Sedation, dizziness, confusion, ataxia, depression, dependency/abuse. |
|Eslicarbazepine2,3 ||400–1200 mg ||1 ||4 days ||Serum sodium and chloride; liver biochemical tests ||As for carbamazepine. |
|Ezogabine3 ||300–1200 mg ||3 ||2–3 days ||ECG to assess QT interval ||Dizziness, somnolence, confusion, vertigo, nausea, ataxia, psychiatric disturbances, prolonged QT interval, retinal abnormalities.7 |
|Felbamate2,3,6,8 ||1200–3600 mg ||3 ||4–5 days ||CBC ...|