Generalized Myoclonus

Abstract

Movement disorders have been reported as rare complications of stroke. The basal ganglia have been implicated in the pathophysiology of most post-stroke dyskinesias. We outline different types of post-stroke myoclonus and their possible pathophysiology. A middle-aged man developed generalized myoclonus after an ischemic stroke in the superior midbrain and subthalamic nuclei. Spontaneous resolution was seen by 72 hours. A lesion to the subthalamic nuclei disrupted the normal thalamic inhibition, which likely led to the involuntary movements seen in our patient. In this case, myoclonus was generalized, which, to the best of our knowledge, has not been reported in the literature as a direct consequence of focal stroke.Keywords stroke, cerebrovascular disorders, movement disorders, clinical specialty, stroke and cerebrovascular disease, clinical specialty Movement disorders are rare complications of stroke. These can manifest as either long-term sequelae (usually after motor function has been partially or totally regained) or, less commonly, an immediate consequence of brain ischemia or hemorrhage. We report a case of a 61-year-old man with controlled hypertension on metroprolol who was found unresponsive in his home. He was initially transferred by ambulance to an outside hospital, where a nonenhanced head computed tomography (CT) was negative. He was given phenytoin 1000 mg intravenously (IV) and decadron 20 mg IV prior to arrival at our center. On our initial neurologic examination performed 3.5 hours after he was found unresponsive, he was stuporous and not responding to commands. He was withdrawing to pain in all 4 extremities and an extensor plantar reflex was noted on the right. Cranial nerves showed fixed and unequal pupils (right 5 mm and left 2 mm), left eye hypertropia, and right eye exotropia. Corneal and gag reflexes were present. No involuntary movements were appreciated. His National Institutes of Health Stroke Scale score was 22. General examination revealed an irregular heart rate and a blood pressure of 131/76 mm Hg. His electrocardiography showed atrial fibrillation. He was intubated immediately for airway protection after apneic breathing episodes were noted. Rocuronium was used for intubation, and he was premedicated with lidocaine and etomidate. After intubation, a single propofol bolus was given for transient hypertension and agitation. His oxygen saturation remained over 95% at all times. Urine toxicology and serum biochemistry that included a basic metabolic panel, cardiac, and liver enzymes were normal, except for the serum creatine kinase level that was found to be elevated (ie, 748 IU/L). A repeat nonenhanced head CT showed areas of hypoattenuation in the brain stem. Subsequent CT angiography was normal, with no evidence of large-vessel stenosis or embolus. Brain magnetic resonance imaging (MRI) showed clear evidence of restricted diffusion in the right and superior aspects of the midbrain, extending bilaterally upward into the subthalamic nuclei, which was also seen on fluidatten...

Myoclonic Disorders

“…Brainstem-generated myoclonus seems to underlie cases of myoclonus in basilar occlusion, superficially resembling short generalized seizures in unconscious patients. In single cases, unilateral subcortical infarction was related to generalized myoclonus due to an undefined mechanism [ 109 ]. Focal myoclonus has also been reported following thalamic hemorrhage [ 110 ].…”