Coma
Definitions
Consciousness: awareness of self and environment; requires both arousal and mental content; requires integrity of reticular activating system and cerebral cortex.
Lethargy, obtundation, stupor, coma: states of progressively reduced responsiveness to external stimuli.
Coma: deep, sustained unconsciousness. No volitional movement; no or little involuntary response to verbal stimuli, shouting, shaking, or pain.
Confusion, delirium: acute state of inattentiveness, altered mental content, and either agitation or decreased response to external stimuli.
Examination and Major Diagnostic Procedures
Initial Approach
Detect and treat any life-threatening condition, e.g., protect airway, ensure adequate ventilation, stop hemorrhage, support circulation, monitor for arrhythmia.
If diagnosis unknown, draw blood for glucose determination; then give intravenous thiamine (50 mg) and 50% dextrose (1–2 ampules D50 solution). If opiate overdose possible, give intravenous naloxone (0.4 mg). If trauma suspected, assume damage to internal organs and cervical fracture until radiographs assure otherwise.
Obtain history from accompanying person, including ambulance team, police.
General Examination
Temperature
Fever: consider infection, heat stroke.
Hypothermia: cold exposure (especially with alcoholism), hypothyroidism, hypoglycemia, sepsis, or, infrequently, primary brain lesion.
Pulses
Asymmetry: dissecting aneurysm.
Head
Inspect and palpate scalp for signs of trauma. Blood in external ear canal (Battle sign) or around eyes (raccoon sign) suggests skull fracture. Inspect ears and nose for blood, CSF.
Neck
Stiff neck (on passive flexion, not lateral rotation or tilting): meningitis, subarachnoid hemorrhage, foramen magnum herniation.
Resistance in all directions: bone or joint disease, including fractures (exclude cervical fracture before checking for stiff neck).
Other Areas
Skin, nails, mucous membranes: pallor, cherry-redness, cyanosis, jaundice, sweating, uremic frost, myxedema, hypo- or
hyperpigmentation, petechiae, dehydration, decubitus ulcers, signs of trauma.
Breath: acetone, alcohol, fetor hepaticus.
Fundi: papilledema, hypertensive or diabetic retinopathy, retinal ischemia, Roth spots, granulomas, subhyaloid hemorrhages.
Urinary or fecal incontinence: unwitnessed seizure, especially if patient awakens spontaneously.
Respiration
Cheyne-Stokes respiration (CSR): periods of hyperventilation and apnea alternating in crescendo-decrescendo fashion. Bilateral cerebral disease, including impending transtentorial herniation, upper brainstem lesions, metabolic encephalopathy. Patient usually not in imminent danger. “Short-cycle CSR” (cluster breathing), with less smooth waxing and waning: often posterior fossa lesion or dangerously elevated intracranial pressure.
Sustained hyperventilation: usually metabolic acidosis, pulmonary congestion, hepatic encephalopathy, or analgesic drugs; rarely, lesion in rostral brainstem.
Apneustic breathing: inspiratory pauses; pontine lesions (especially infarct); infrequently, metabolic coma or transtentorial herniation.
Ataxic breathing (Biot breathing): variably irregular rate and amplitude; medullary damage. Can progress to apnea (abruptly with posterior fossa lesions).
Ondine curse: loss of automatic respiration; preserved voluntary breathing; must be alert to breathe. Medullary lesion; as patient falls asleep, apnea can be fatal.
Stertorous breathing (i.e., inspiratory noise): airway obstruction.
Other ominous respiratory signs: end-expiratory pushing (like coughing); “fish-mouthing” (lower-jaw depression with inspiration).
Pupils
Anisocoria: pupil inequality. If <0.5 mm in awake, otherwise normal person, likely physiologic. Always assumed to be pathologic in coma.
Parasympathetic lesions: e.g., oculomotor nerve compression in uncal herniation or after rupture of internal carotid artery
aneurysm; pupil enlarges; ultimately, full dilation, no reaction to light.
Sympathetic lesions: intraparenchymal (e.g., hypothalamic injury or lateral medullary infarct) or extraparenchymal (e.g., invasion of superior cervical ganglion by lung cancer); Horner syndrome (miosis, ptosis, anhydrosis).
Combined sympathetic and parasympathetic lesions: e.g., midbrain destruction; one or both pupils in mid-position, unreactive.
Pinpoint but reactive pupils: pontine hemorrhage, opiate intoxication.
Fixed, dilated pupils: confirm with bright light. Consider (a) anticholinergic drugs (atropine, glutethimide, amitriptyline, antiparkinsonian agents); (b) hypothermia; (c) severe barbiturate intoxication (b and c can cause reversible picture simulating brain death); (d) ongoing or recent seizure (pupil abnormality may be unilateral); (e) anoxic-ischemic event (fixed pupils imply poor prognosis).
Some pupillary abnormalities due to local trauma, surgical scars.
Eyelids and Eye Movements
Closed eyelids in comatose patient: lower pons intact.
Blinking: sign of reticular activity.
Conjugate eye deviation: (a) away from hemiparetic limbs: destructive cerebral lesion (on side of eye deviation); (b) toward paretic limbs: pontine lesion, seizure, or “wrong-way” gaze paresis of thalamic hemorrhage.
Eyes dysconjugate at rest: paresis of individual muscles, internuclear ophthalmoplegia, or preexisting tropia or phoria.Related posts:
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