[Acute global amnesia as an exclusive presenting symptom of thalamic infarct: a diagnostic challenge]

Isolated acute amnesia is an exceptional presenting symptom of thalamic stroke. This study analyses the clinical profile, the diagnosis, the treatment and the prognosis of these patients.

We conducted a retrospective review of the cases of thalamic infarct that presented exclusively as acute amnesia in our university tertiary hospital (n = 3) and a review of similar cases in PubMed (n = 20). 48% presented at least one risk factor of stroke (arterial hypertension, dyslipidaemia, diabetes mellitus, atrial fibrillation or a previous stroke). Amnesia was anterograde in three cases (13%) and global in the remaining 20 (87%). The infarct was detected in neuroimaging studies carried out within the first 24 hours in one patient (4%) and later in all the others; the average time until a diagnosis was established was 11 days. The initial CT scan was normal in five patients (22%). Eight cases (35%) required magnetic resonance imaging to detect the infarct. Of these, four subjects were studied directly with MR imaging. Amnesia clearly improved in eight patients (35%), and three of them (13%) made a full recovery. Fifteen patients (65%) presented mnemonic sequelae that interfered with their functional capacity. The clinical picture lasted less than 24 hours in two patients (9%). None of the cases received revasculisation therapy in the acute phase.

The diagnosis of thalamic infarcts that begin exclusively with amnesia is very difficult and this has negative repercussions on their treatment in the acute phase. These infarcts can produce a functionally disabling memory deficit in a high percentage of patients.