Reversible monoparesis following decompressive hemicraniectomy for traumatic brain injury

Object. The "syndrome of the trephined" is an uncommon and poorly understood disorder of delayed neurological deficit following craniectomy. From the authors' extensive experience with decompressive hemicraniectomy for traumatic brain injury (TBI), they have encountered a number of patients who developed delayed motor deficits, also called "motor trephine syndrome," and reversal of the weakness following cranioplasty repair. The authors set out to study motor function systematically in this patient population to define the incidence, contributing factors, and outcome of patients with motor trephine syndrome. Methods. The authors evaluated patient demographics, injury characteristics, detailed motor examinations, and CT scans in 38 patients with long-term follow-up after decompressive hemicraniectomy for TBI. Results. Ten patients (26%) experienced delayed contralateral upper-extremity weakness, beginning 4.9 ± 0.4 months(mean ± standard error) after decompressive hemicraniectomy. Motor deficits improved markedly within 72 hours of cranioplasty repair, and all patients recovered full motor function. The CT perfusion scans, performed in 2 patients, demonstrated improvements in cerebral blood flow commensurate with resolution of cerebrospinal fluid flow disturbances on CT scanning and return of motor strength. Comparisons between 10 patients with and 20 patients (53%) without delayed motor deficits identified 3 factors - ipsilateral contusions, abnormal cerebrospinal fluid circulation, and longer intervals to cranioplasty repair - to be strongly associated with delayed, reversible monoparesis following decompressive hemicraniectomy. Conclusions. Delayed, reversible monoparesis, also called motor trephine syndrome, is common following decompressive hemicraniectomy for TBI. The results of this study suggest that close follow-up of motor strength with early cranioplasty repair may prevent delayed motor complications of decompressive hemicraniectomy.