Persistent facial myoclonus: a negative prognostic sign in patients with severe brain injury

The determination of long-term prognosis is one of the most difficult tasks in the management of persons with brain injury (BI). Initial Glasgow Score, duration of coma, brain stem reflexes, and pupillary responses are all clinical findings that have been related to outcome in BI. We describe another easily observable clinical finding, persistent facial myoclonus (PFM), which may provide additional information on prognosis after severe BI. We retrospectively reviewed 295 consecutive admissions to an inpatient brain injury rehabilitation program. Data extracted included mechanism of injury, patient demographics, admission and discharge Rancho Level (RL), and presence of PFM plus first date of description. Of the total admissions, 68 (23%) were RL < or = 2 on admission and of those 68, nine (13%) demonstrated PFM. Twenty-seven of 59 patients without PFM advanced to RL > 3 but none of those with PFM progressed to RL > 2 (Fisher's exact probability = .007). Mean time from injury to PFM description was 10.5 months (SD = 11.8, range, 2.5 to 25.0 months) and mean time from description to discharge was 7.1 months (SD = 6.6, range, 2.0 to 22.5 months). Four of the nine PFM patients had evidence of brain stem injury on computed tomography or magnetic resonance imaging scans, a much higher percentage than in the larger population. We postulate that patients with PFM after TBI represent a subgroup of patients with severe diffuse axonal injury with brain stem lesions.