Intracalvarial Penetration of a Halo Pin During Treatment of an Odontoid Fracture in an Elderly Patient: A Case Report

BACKGROUND: We present the case of an 86-year-old woman with impaired consciousness after halo pin intracalvarial penetration, as well as a review of the literature.
CASE REPORT: An 86-year-old woman had an Anderson type II displaced odontoid fracture with serious instability. A decision was made to treat the patient with halo vest immobilization followed by surgical atlantoaxial fixation.
At first a halo device was fitted with 4 titanium alloy fixation pins used to stabilize the crown. Four days after application of the halo fixation device, posterior atlantoaxial fixation was performed. During surgery, no particular problems were encountered and the patient recovered from anesthesia without any particular adverse events. Two days after surgery, impaired consciousness was noted in the morning. The level of consciousness measured by the Glasgow coma scale (GCS) was 7/15 points. An immediate head CT scan showed intracalvarial penetration of the halo pin. Halo pins were removed in the operating room on the same day. The next day after removal of the halo fixation device, consciousness of the patient fully returned to alert (GCS of 15/15 points). Two weeks later, the patient was discharged with a cervical orthosis under crutch gait. At 6 months postoperatively, bone union was obtained and her neck pain completely disappeared.
CONCLUSIONS: Pin penetration through the inner table of the calvarium is rare but is one of the most serious issues when treating the cervical spine disorders with the halo fixation device. Once pin intracalvarial penetration has been detected, prompt intervention should be performed to ensure a favorable prognosis.

Keywords: complication, Atlantoaxial Fixatio, Halo Device, Halo Pin Penetration, impaired consciousness, odontoid fracture