Choreoathetosis/ballismus associated with pentamidine-induced hypoglycemia in a patient with the acquired immunodeficiency syndrome

Post-stroke dyskinesias

Strokes, whether ischemic or hemorrhagic, are among the most common causes of secondary movement disorders in elderly patients. Stroke-related (vascular) movement disorders, however, are uncommon complications of this relatively common disease. The spectrum of post-stroke movement disorders is broad and includes both hypo- and hyperkinetic syndromes. Post-stroke dyskinesias are involuntary hyperkinetic movements arising from cerebrovascular insults and often present with mixed phenotypes of hyperkinesia which can sometimes be difficult to classify. Nevertheless, identification of the most relevant motor phenotype, whenever possible, allows for a more specific phenomenological categorization of the dyskinesia and thus helps guide its treatment. Fortunately, post-stroke dyskinesias are usually self-limiting and resolve within 6 to 12 months of onset, but a short-term pharmacotherapy might sometimes be required for symptom control. Functional neurosurgical interventions targeting the motor thalamus or globus pallidus interna might be considered for patients with severe, disabling, and persistent dyskinesias (arbitrarily defined as duration longer than 12 months).

Hyperglycemic nonketotic states and other metabolic imbalances

Hemichorea and generalized chorea are well-recognized syndromes associated with nonketotic hyperglycemia. This condition usually occurs in older age, affects females more than men, and often heralds a new diagnosis of diabetes, usually type 2. It may resolve over days with treatment of the underlying hyperglycemia or persist for years. Magnetic resonance imaging is very characteristic, and shows T1 hyperdensity in the striatum. The underlying pathophysiology is not clear, but recent evidence suggests that the imaging may represent zinc, as opposed to calcium. Tetrabenazine has worked well when symptomatic treatment is required. Other rare causes of metabolic choreas include hypoparathyroid abnormalities, hypoglycemia, and hypernatremia.

Hemiballismus

Hemiballism is a relatively rare hyperkinetic movement disorder characterized by involuntary, violent, coarse and wide-amplitude movements involving ipsilateral arm and leg. Although classically related to lesions in the subthalamic nucleus, in clinical-radiological series of hemiballism most patients had lesions outside this nucleus, involving mainly other basal ganglia structures. It has been suggested that abnormal neuronal firing patterns in the internal segment of the globus pallidus may be related to the pathogenesis of hemiballism. Stroke is the most common cause, but in recent years an increasing number of patients with hemiballism associated with nonketotic hyperglycemia or with complications of human immunodeficiency virus (HIV) infection have been reported. Contrarily to what was stated in older literature, hemiballism has, in general, a relatively good prognosis. Depending on the underlying causes, many patients may experience spontaneous improvements or remissions. Treatment should be directed to the cause of hemiballism. Symptomatic treatment includes the use of drugs, particularly blockers of striatal D2 dopamine receptors and tetrabenazine. Surgical treatment, especially pallidotomy, is a therapeutic option for the minority of patients with severe persistent disabling hemiballism.

Hemiballism: revisiting a classic disorder

Hemiballism is a rare movement disorder that presents with unilateral flinging movements of the limbs. In traditional teaching, it has been characterised as almost pathognomonic of a lesion in the subthalamic nucleus (STN). The prognosis was described as grave, with severe disability and death in many cases. However, review of more recent reports shows that the STN is directly involved in only a minority of cases. The prognosis is benign in most cases, with almost all patients responding well to treatment and many having spontaneous remission, although long-term prognosis of cerebrovascular disease may not be so good. There have also been recent insights into the pathophysiology of hemiballism, which have emphasised the importance of altered firing patterns in basal-ganglia structures. Recent studies have pointed to previously unrecognised causes, particularly non-ketotic hyperosmolar hyperglycaemia and complications of HIV infection, that may account for a substantial proportion of cases of hemiballism.