Neurological Examination
This domain rewards a reproducible, hierarchical examination and correct interpretation of single signs. Describe how you would examine a comatose patient, because that is a common station.
Consciousness and the brainstem
- GCS records best eye, verbal and motor responses. M6 obeys, M5 localises, M4 withdraws, M3 abnormal flexion, M2 extension, M1 none. An intubated patient scores VT. Motor score and pupils carry most prognostic weight.
- Examine brainstem function from the top down: pupils, corneal reflexes, oculocephalic then caloric responses, gag and cough, respiratory pattern. Fixed dilated pupils indicate midbrain or CN III compression; pinpoint pupils with absent oculocephalic responses indicate pontine damage.
- Decorticate posturing reflects rubrospinal drive; decerebrate posturing reflects vestibulospinal drive and a lower lesion.
Cortical, cranial nerve and segmental examination
- Aphasia versus dysarthria: test fluency, comprehension and repetition. Wernicke is fluent with poor comprehension, Broca is non-fluent and effortful, conduction has repetition out of proportion to other domains.
- Upper motor neurone signs: increased tone, hyperreflexia, Babinski. Lower motor neurone signs: wasting, fasciculation, reduced tone and reflexes.
- Key dermatomes: C6 thumb, C7 middle finger, C8 little finger, L4 medial malleolus, L5 dorsum of foot, S1 lateral foot. Reflexes: biceps and brachioradialis C5-6, triceps C7, knee L3-4, ankle S1.
Grading scales
Subarachnoid haemorrhage: WFNS uses GCS and focal deficit, grade 1 GCS 15 without deficit to grade 5 GCS 3 to 6; Hunt and Hess adds headache and neck stiffness. Stroke: NIHSS 0 to 42; fluctuating scores suggest a stuttering deficit or ongoing ischaemia.
Worked example
After a fall a 58-year-old is intubated. The right pupil is 6 mm and fixed, the left 3 mm and reactive, and the left arm extends to pain. Right brainstem compression with left hemiparesis localises to a right-sided mass. GCS is E1 VT M2, that is 3T.
Traps
- Quoting a total GCS without its components.
- Skipping the gag reflex in a comatose patient.
- Attributing a fixed pupil to herniation when there is direct eye trauma.
- Labelling fluctuating weakness as functional without re-examination.