Paroxysmal Sympathetic Hyperactivity Versus Sepsis in Disorders of Consciousness
A 22-year-old man is 3 weeks post severe TBI (diffuse axonal injury pattern) and remains in a vegetative state. He has episodes of tachycardia to 140 bpm, systolic blood pressure to 180 mmHg, tachypnea, diaphoresis, and extensor posturing, occurring several times daily and lasting 20-40 minutes. Between episodes he is stable. Temperature is 38.3 C. He has a tracheostomy and a urinary catheter. White blood cell count is 14,000 with a left shift; urinalysis shows pyuria and nitrites. He is on no sedatives. Pupils are equal and reactive.
1. How do you distinguish paroxysmal sympathetic hyperactivity from sepsis and other causes of these episodes?
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Both are plausible and may coexist. Key distinctions:
Paroxysmal sympathetic hyperactivity (PSH): episodes are stereotyped, triggered by stimulation (suctioning, turning, pain), with simultaneous sympathetic surge (tachycardia, hypertension, tachypnea, diaphoresis, hyperthermia) and dystonic posturing, resolving between episodes. It typically emerges after a period of coma and is associated with diffuse axonal injury and younger age. The diagnosis requires excluding other causes.
Sepsis: fever, tachycardia, tachypnea, and leukocytosis fit, and the urinalysis suggests a urinary tract infection. Sepsis is usually continuous or progressive rather than stereotyped and stimulation-triggered, and it does not produce extensor posturing.
Other considerations:
- Neuroleptic malignant syndrome or serotonin syndrome - unlikely given no offending agents.
- Seizures - nonconvulsive status can cause autonomic fluctuations; EEG is warranted if episodes are paroxysmal and unexplained.
- Withdrawal - none, given no sedatives.
- Hydrocephalus, herniation, or new intracranial event - imaging if the exam changes.
The practical approach: treat the suspected UTI and obtain cultures, but also characterize the episodes (triggers, stereotypy, duration, inter-episode exam). A structured tool such as the PSH Assessment Measure can help. Do not attribute everything to PSH until infection is addressed, and do not dismiss stereotyped autonomic storms as 'just sepsis.'
2. What management would you initiate for the episodes, and how do you monitor response?
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Treat reversible causes first: antibiotics for the UTI based on culture, remove or change the catheter, and evaluate for other sources. Continue fever control and supportive care.
For PSH:
- Trigger management: minimize noxious stimuli, premedicate before suctioning and turning, optimize bowel and bladder care, and treat pain.
- Symptom control: nonselective beta-blockers (e.g., propranolol) are commonly used; gabapentin, clonidine, and baclofen have been used. Bromocriptine and other agents are described in refractory cases. Avoid agents that worsen cognition or cause hypotension.
- Refractory cases: consider intrathecal baclofen or other specialist options.
Monitoring: keep an episode diary with triggers, duration, and vital signs; track response to medication; monitor for hypotension and bradycardia with beta-blockade; reassess infection and repeat cultures; obtain EEG if episodes persist or the exam changes. Coordinate with nursing and therapy to reduce triggers. Reassess the level of consciousness and prognosis serially, and involve family in understanding the episodes.