Neurological Aspects of Insulinomas

Neurological involvement occurred in every one of a series of 30 patients with an insulinoma. The episodic nature of the hypoglycaemia caused symptoms and signs to fluctuate and often led to delay in diagnosis (mean length of history was 3 years). The commonest feature at first presentation was confusion (20 instances), but as the illness evolved, coma (16 instances) and convulsions (8 instances) became more frequent. Objective weakness was found in 7 patients, with 3 examples of hemiparesis and 2 each of paraparesis and monoparesis; in all, the weakness resolved over a period of 1 hr to 3 days when normoglycaemia was maintained. Other neurological features included subjective visual disturbances, headache, dysarthria and ataxia. 220 patients with an insulinoma from 7 series in the literature were reviewed. The high incidence of neurological features was confirmed, with confusion (152 cases), coma (82 cases) and convulsions (58 cases) predominating. Visual disturbances were common, though not accurately quantified in some series. Objective evidence of weakness on the other hand was reported in only 6 of the 222 patients. Other less common symptoms included headache (18 instances) and peripheral paraesthesiae (14 instances). In the 7 series reviewed, as in our own, it was found that in any one patient, each episode of hypoglycaemia was accompanied by the same symptom complex. The presence of an insulinoma should be considered in any patient with unusual, or inexplicable neurological features, particularly when they are intermittent. The diagnosis can be confirmed by demonstrating an inappropriately high circulating insulin level, for the ambient blood glucose concentration.