Case 16 - Involuntary movements
What is the lesion?
The list of causes of chorea (and ballismus) is enormous – but thankfully that for acute chorea is much smaller after we remove slowly progressive, neurodegenerative conditions, many of which are genetic - the best-known being Huntington's.
If we then restrict it to one side of the body the list shrinks further.
This patient went to bed fine and woke up with profound hemichorea-hemiballism. Only lesions capable of presenting quickly should be considered.
A vascular lesion in the basal ganglia is a concern, and probably the major cause of this presentation. Causes are either a small lacunar infarction through the various perforating arteries which perfuse the basal ganglia, or a haemorrhage into the parenchyma. This patient has multiple vascular risk factors and a stroke of either type is likely.
Diabetes can cause severe hyperglycaemia which can cause hemichorea-hemiballismus, known as hypergylcaemic hemichorea or diabetic striatopathy. It is interesting that this systemic effect produces such a lateralised manifestation - this is unusual for metabolic neurological disorders. The mechanism is not known, but it may reflect asymmetric microvascular congestion with hyperviscous and hyperosmolar blood, and also directly toxic effects on cells. It is mainly seen in older people with type II diabetes and with non-ketotic hyperglycaemia – so this patient could well be at risk. We should never forget to check glucose levels in acute neurological situations - but especially not this one!
Rarer considerations for hemichorea include mass lesions in the deep nuclei, which disrupt the circuitry - lymphoma and toxoplasmosis are examples. It can also be seen with inflammatory disorders such as lupus and antiphospholipid syndrome and rarely is reported in multiple sclerosis (unusually for a disorder predominantly related to white matter). It is reported in some cases of polycythaemia rubra vera, as well as some cases of encephalitis and paraneoplastic disorders such as anti-CV2 disease.
While sudden-onset of such syndromes appears vascular, this isn't entirely reliable - some of these progressive causes may appear to come on abruptly (presumably once the tonic thalamic inhibition is released) - then worsen over time, and at the onset we don't know how they will progress. We do at least know that this is already severe (she can't use the arm or leg or stand up) - and given her vascular risk factors, age, and the fact that vascular lesions are the commonest cause of this - it seems like this is most likely to be vascular.
Clinical formulation