The diagnostic value of the neurological examination in coma of unknown etiology

Wolf U Schmidt,C J Ploner,M Lutz,M Braun

doi:10.1007/s00415-021-10527-4

Abstract

BackgroundIdentifying the cause of non-traumatic coma in the emergency department is challenging. The clinical neurological examination is the most readily available tool to detect focal neurological deficits as indicators for cerebral causes of coma. Previously proposed clinical pathways have granted the interpretation of clinical findings a pivotal role in the diagnostic work-up. We aimed to identify the actual diagnostic reliability of the neurological examination with regard to identifying acute brain damage.MethodsEight hundred and fifty-three patients with coma of unknown etiology (CUE) were examined neurologically in the emergency department following a predefined routine. Coma-explaining pathologies were identified retrospectively and grouped into primary brain pathology with proof of acute brain damage and other causes without proof of acute structural pathology. Sensitivity, specificity and percentage of correct predictions of different examination protocols were calculated using contingency tables and binary logistic regression models.ResultsThe full neurological examination was 74% sensitive and 60% specific to detect acute structural brain damage underlying CUE. Sensitivity and specificity were higher in non-sedated patients (87/61%) compared to sedated patients (64%/59%). A shortened four-item examination protocol focusing on pupils, gaze and pyramidal tract signs was only slightly less sensitive (67%) and more specific (65%).ConclusionsDue to limited diagnostic reliability of the physical examination, the absence of focal neurological signs in acutely comatose patients should not defer from a complete work-up including brain imaging. In an emergency, a concise neurological examination should thus serve as one part of a multimodal diagnostic approach to CUE.

Highlights

Coma of unknown etiology (CUE) is a challenging emergency
We report on 853 emergency patients who were unconscious for unknown reasons at the time of examination in the ED and at least until all emergency diagnostics were completed (462 males, 391 females; median age 65, IQR 48–77 years.; median Glasgow Coma Scale (GCS) 5, IQR 3–8)
In nonsedated patients (NSPs; R2 = 0.285, HLT not significant), sensitivity of the full neurological examination increased to 87% while specificity remained at 61%

Summary

Introduction

Coma of unknown etiology (CUE) is a challenging emergency. CUE defines an impairment of consciousness for reasons other than traumatic brain injury or cerebral hypoperfusion in cardiac arrest. Examination techniques have frequently been considered reliable tools to discriminate acute structural brain damage from other causes [5, 8, 9]. At least in awake patients, clinical neurological findings were shown to have limited sensitivity and specificity [12,13,14,15]. Identifying the cause of non-traumatic coma in the emergency department is challenging. Methods Eight hundred and fifty-three patients with coma of unknown etiology (CUE) were examined neurologically in the emergency department following a predefined routine. Results The full neurological examination was 74% sensitive and 60% specific to detect acute structural brain damage underlying CUE. Conclusions Due to limited diagnostic reliability of the physical examination, the absence of focal neurological signs in acutely comatose patients should not defer from a complete work-up including brain imaging. A concise neurological examination should serve as one part of a multimodal diagnostic approach to CUE

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