The Neurological Evaluation of a Comatose Patient Definition: • Coma: a state of unresponsiveness; the absence of consciousness Differential Diagnosis: • Unresponsive wakefulness syndrome • Locked-in syndrome • Mutism Pathophysiology: • Severe injury/dysfunction to the bilateral cortex → Awareness • Injury to brainstem (to the ascending reticular activating system/ARAS) → Arousal How to Examine a Comatose Patient 1. Ensure the patient is off sedation, if safe to stop 2. Track response to voice or noxious stimulation 3. Test downward eye movement (i.e., is the patient locked in?) 4. Test if patient blinks to threat Cranial Nerves: Brainstem Reflexes: • Pupillary light reflex • Corneal reflex • Oculocephalic reflex • Vestibulo-ocular reflex • Gag reflex • Cough reflex Pupils: • Anisocoria + Coma → high concern for structural etiology of coma Abnormal Eye Movements: • Bobbing: Rapid downward movement followed by slower return to previous gaze position; indicates pontine lesion • Dipping: Slow downward movement followed by rapid return to previous gaze position; indicates pontine lesion • Roving eye movements: Slow horizontal movements; also normal in sleep; indicators of cortical etiology for the coma • Forced gaze deviation: Not reversed by oculocephalic reflex; indicates ipsilateral hemispheric lesion; usually of frontal eye fields or brainstem Motor/Sensory: • Tone: check for asymmetry and hypotonia/flaccid limbs vs hypertonia (spasticity, rigidity, paratonia) • Apply a noxious stimulation to all four limbs and document response (tests motor and sensation) - Possible painful stimuli: 1. Supraorbital pressure 2. Sternal rub 3. Nail bed pressure 4. Trapezius squeeze • Possible responses to pain: localizes, flexion withdrawal, abnormal flexor response (decortication), abnormal extensor response (decerebration), no response • Document presence of spontaneous movements (i.e. myoclonic movements, tremors) Reflexes: • Deep tendon reflexes • Plantar responses • Check for presence of clonus • Carefully note any asymmetry Extra Tests: • Examine for signs of meningoism (may not be present in coma) • If ok with ICU team, place patient on pressure support ventilation and observe breathing Localizing Posturing: • Decorticate posturing: Arms flexed at the elbow in direction to the body; wrists clenched; legs extended; lesion above the red nucleus • Decerebrate posturing: Arms extended; wrists flexed back, away from the body; wrists clenched; legs extended; lesion below the red nucleus Glasgow Coma Scale (GCS): • Eye opening • Verbal response • Motor response Full Outline of UnResponsiveness (FOUR Score): • Eye response • Motor response • Brainstem reflexes • Respiration By Dr. Gabriela Figueiredo Pucci @neudrawlogy and Dr. Casey Albin MD @caseyalbin #PhysicalExam #neurology #comatose #diagnosis
