Paroxysmal sympathetic hyperactivity in the neurological intensive care unit.

OBJECTIVE: To assess the incidence and associations of paroxysmal sympathetic hyperactivity (PSH) among febrile patients in the neurological intensive care unit (NICU).
METHODS: Prospective data collection of consecutive patients admitted to an academic NICU for >48 hours. Fever was defined as body temperature >38.3 degrees C (101.0 degrees F) on at least one measurement for two consecutive days. PSH was defined by the transient presence of four of the following six criteria: fever, tachycardia, hypertension, tachypnea, excessive diaphoresis and extensor posturing or severe dystonia in the absence of other potential causes for these clinical signs.
Methods: Ninety-three patients were included. Traumatic brain injury (TBI) was the primary diagnosis in 43 patients (46%). PSH were diagnosed in 17 patients (18%). It occurred in 14/43 patients (33%) with TBI but only 3/50 patients (6%) with other primary disorders (p = 0.01). Patients with PSH were younger (mean age: 35 +/- 14 versus 51 +/- 18 years old in the rest of the population) (p = 0.01), although the difference did not reach statistical significance when only TBI patients were included in the analysis (mean age: 35 +/- 15 years old in TBI patients with PSH versus 46 +/- 19 years old in TBI patients without PSH; p = 0.07). Duration of fever in patients with PSH (mean: 10.5 +/- 7 days; median: 9 days) was significantly longer than in the rest of the population (mean: 5.1 +/- 3 days) (p<0.001); the difference remained significant when the analysis was restricted to TBI patients (p = 0.001).
CONCLUSION: Episodes of PSH occur in one-third of TBI patients but are rare in other acute neurological conditions. They are more frequent in younger patients and are associated with prolonged duration of fever.