Case 11. Progressive communication difficulties
What is the lesion?
The symptoms came on over several weeks - a subacute tempo.
The commonest cause of dysphasia by far is stroke (i.e. vascular) – and the general public are aware of this thanks to the FAST (Face-Arm-Speech-Time) campaign - but stroke produces sudden-onset dysphasia and the history here is far too gradual.
Infectious or inflammatory brain lesions could produce acute and subacute dysphasia if they affected crucial structures, but usually would arise over hours-days. The major infectious cause is viral encephalitis, which often features dysphasia in addition to confusion (which isn't present here) - but this is typically aggressive, and people deteriorate rapidly, progressing to seizures and coma, and die within days without treatment. There are some subacute neuroinflammatory processes but it would have to be a sizeable lesion in the area we are expecting pathology - and this isn't typical of any particular illness. For example it isn't a recognised presentation in autoimmune encephalitis and certainly not in multiple sclerosis.
At the opposite extreme, primary progressive aphasia is a form of neurodegenerative disorder in which language centres gradually lose neurons and people lose the ability to communicate. This happens slowly, over many years, much slower than this patient’s history.
Creutzfeldt-Jakob disease can progress over this timeframe with language deficits, and visual features are common - but by now there would likely be a more diffuse syndrome involving cognitive features in addition to movement disorders (ataxia, myoclonus).
The progression of symptoms over 1-2 months is ominous. It is slower than the more acute pathologies above, which raises serious concern for a tumour. If there is a tumour, it is growing quickly, with symptoms progressing over a relatively short time frame compared to what is seen with more indolent lesions - so we would be dealing with something relatively high-grade.
Clearly this patient needs imaging to clarify - and a tumour sounds the most concerning possibility.
Clinical formulation