ICU · Anatomy
Neuroanatomy — Brainstem, Cranial Nerves & Spinal Cord
Also known as Neuroanatomy · Brainstem · Cranial nerves · Spinal cord tracts · Corticospinal tract · Spinothalamic tract · Artery of Adamkiewicz · Brainstem reflexes · Circle of Willis · Cerebral cortex · Basal ganglia · Blood-brain barrier · Ventricular system
Neuroanatomy for the ICU First Part: the cerebral cortex (frontal, parietal, temporal, occipital lobes and their functions), the basal ganglia and their direct/indirect pathways, the thalamus and hypothalamus, the limbic system, the brainstem (midbrain, pons, medulla) and its vital centres, the twelve cranial nerves with their main functions, the brainstem reflexes used in coma and brain-death assessment (pupillary, corneal, gag/cough, oculocephalic), the cerebellum, the ventricular system and CSF flow, the Circle of Willis and the MCA/ACA/PCA territories, the major spinal cord tracts (corticospinal, spinothalamic, dorsal columns) and their blood supply, the blood-brain barrier, and the autonomic nervous system.
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A 54-year-old is on ICU day 4 after an out-of-hospital ventricular fibrillation arrest with a 25-minute down-time. Targeted temperature management at 36 C is done, he has been rewarmed 24 hours, and he is GCS 3 with absent brainstem reflexes on a midazolam and fentanyl infusion. The consultant asks you to outline the anatomical basis of the bedside brain-death examination.[1]
The question that decides this patient's trajectory is the question every neuro exam turns on: which cranial nerve sign localises the lesion — and at what brainstem level? The pupillary reflex tests the midbrain (CN II in, CN III out); the corneal tests the pons (V in, VII out); the gag and the apnoea test the medulla (IX, X, and the respiratory centre). Walk the brainstem from top to bottom and the anatomy tells you how deep the injury goes.[1][5]
References15ShowHide
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