Focal Neurological Deficit at Onset of Aneurysmal Subarachnoid Hemorrhage: Frequency and Causes

Background and Aim: Focal neurological deficit (FND) is a recognized presenting symptom of aneurysmal subarachnoid hemorrhage (SAH). However, little is known on how often aneurysmal SAH patients present with FND and what the responsible mechanisms are. The aim of this study was to examine the frequency and causes of FND at onset in aneurysmal SAH. Methods: We reviewed the records of consecutive aneurysmal SAH patients over 5 years and identified those who presented with FND. We developed several potential mechanisms for FND based on consensus between 2 separate evaluating neurologists. We then compared the characteristics of aneurysmal SAH patients who presented with and without FND. Logistic regression models were used to assess for association of FND with poor outcome. Results: Of a total of 213 patients, 10.3% presented with FND. The junction of the internal carotid and posterior communicating arteries was the most common aneurysm location in patients with FND (36.4%). Causes of FND at presentation were intraparenchymal hematoma in 45.5%, early cerebral infarction in 22.7%, parenchymal compression by subarachnoid thrombus in 18.2%, and seizure with Todd's paralysis in 13.6%. Patients with FND were older (P = .001) and had higher rates of in-hospital death and severe disability at discharge (P < .0001), compared to those without focal deficit. FND was independently associated with poor outcome (odds ratio: 4.62, confidence interval: 1.41-15.14; P = .01). Conclusion: One in every 10 aneurysmal SAH patients presents with FND. FND at presentation has diverse mechanisms, is not associated with a specific aneurysm location, and is independently associated with poor outcome.