A 24-year-old previously healthy man is brought to the emergency department after a motorcycle collision. The patient was intubated in the field. On arrival, Glasgow Coma Scale is 3/15. CT scan of the head shows left temporoparietal skull fractures, a large subdural hematoma, and diffuse cerebral edema. The patient undergoes hematoma evacuation and decompressive craniotomy. He is admitted in the neurocritical care unit, and supportive measures are provided. His clinical status gradually improves, and the patient is extubated on day 9. Over the next 15 months the patient opens his eyes spontaneously, gazing randomly around the room, but does not visually track moving objects. Bilateral pupils are equally responsive to light. He does not vocalize or follow instructions. The patient moves all 4 extremities, but the movements are not purposeful and there is no withdrawal to painful stimuli. The patient tolerates feeding via a percutaneous gastrostomy tube but has urinary and fecal incontinence. Which of the following is the most likely diagnosis?
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Consciousness is clinically characterized by wakefulness with awareness. This patient suffered a catastrophic traumatic brain injury (TBI) and was comatose initially. Coma is an unconscious state in which patients are unawake, unarousable, and unaware. Coma typically progresses toward 1 of 3 neurologic outcomes:
Recovery: Consciousness is restored, but patients typically have residual cognitive, motor, and/or sensory deficits requiring rehabilitation.
Brain death: Cerebral and brainstem function cease. Patients have no cranial nerve reflexes and are apneic (no spontaneous breathing, requiring continuous mechanical ventilation) (Choice A).
Persistent vegetative state (PVS): A chronic state of wakefulness without awareness. Due to the possibility of interim recovery, PVS can be diagnosed only after sufficient time has elapsed (≥12 months) after post-TBI coma.
Patients with PVS are awake, evidenced by spontaneous eye opening and normal sleep-wake cycles. However, they are unaware, as indicated by non-responsiveness to external stimuli, absence of language comprehension or expression, and lack of purposeful visual tracking. Brainstem reflexes (eg, cough, gag, pupillary constriction) are usually intact. Because voluntary sphincter control is lost in PVS, patients have urinary and fecal incontinence. Similarly, control of swallowing (a complex voluntary process) is lost, so patients with PVS require enteral (eg, gastrostomy) tube feedings.
(Choice B) Cataplexy is an abrupt, massive inhibition of muscle tone typically triggered by strong emotions (laughter, fright) in patients with narcolepsy. Patients suddenly go limp and collapse, but they usually recover after a few seconds.
(Choice C) Locked-in syndrome can occur due to osmotic demyelination (eg, excessively rapid hyponatremia correction) or infarction (eg, basilar artery stroke) of pontine corticospinal neurons. As opposed to being unaware and mobile (like this patient), locked-in patients are aware but completely paralyzed except for blinking and vertical eye movement.
(Choice E) Selective mutism is a form of social anxiety disorder in which patients do not verbalize despite negative interpersonal consequences. Despite not speaking, these patients' level of consciousness is intact.
Educational objective:
Persistent vegetative state (PVS), a chronic state of wakefulness without awareness, is a common post-coma outcome following severe brain injury. Patients with PVS have sufficient brainstem function to maintain vital processes such as spontaneous respiration, but require continuous medical care due to absence of purposeful movement and communication.