Review Question - QID 4931

The clinical images are consistent with an abducens nerve palsy which is thought to be a traction injury to cranial nerve VI.

An abducens nerve palsy is the most common cranial nerve complication with halo treatment. It is thought to be a traction injury to cranial nerve VI, which affects the abducens nerve (innervation to the lateral rectus muscles). Patients present with diplopia, and physical exam will show loss of lateral gaze on affected side. Treatment is to decrease the traction of halo immobilization followed by a period of observation. Most cases resolve spontaneously.

Limpaphayom et al. looked at complication rates of using halo traction for correction of spinal deformity or immobilization. They found an overall complication rate of 53% (36/68), with 10% (7/68) of children requiring operative intervention for halo traction complications. The most common complication was pin-site infection, with 76% (13/17) of these resolving with oral antibiotics. Traction-related neurologic injuries occurred in 31% (9/31) of patients, but all resolved with a reduction or removal of traction, with 4 out of 9 events resolving immediately. The authors recommend serial neurologic exams after halo placement and traction reduction, and removal if any neurologic complication is noted.

Caird et al. conducted a retrospective review of 13 patients under 4 years old who had halo application for cervical trauma, arthrodesis, or scoliosis. They reported an average of 8 pins used per patient (range 6-12) and insertional torque of 2 to 4 in-lb. Nine patients (69%) suffered some complication, mostly pin site infection (6 cases), and so they conclude that halo application is safe in toddlers.

Figure A demonstrates the patient attempting to gaze left but with asymmetry between the right and left eyes. The left eye is unable to gaze left due to an abducens nerve palsy. Figure B demonstrates the patient gazing right, with a normal exam and symmetric gaze of both eyes to the right. Images courtesy of Childrens Hospital Los Angeles.

Incorrect Responses:
Answer 1 - Most complications of halo traction, including nerve palsy, resolve with reduced traction and observation.
Answer 2 - The supraorbital nerve is a branch of the frontal nerve providing sensation to the upper eyelid and forehead/scalp. It emerges just above the medial one third of the orbit and is at risk for injury if halo pins are placed too medial above the orbit. It does not result in muscle weakness or gaze problems.
Answer 3 - The supratrochlear nerve is another small branch of the frontal nerve located medial to the supraorbital nerve and providing sensation to the medial forhead, and medial upper eyelid.
Answer 5 - Cranial nerve VII is the facial nerve, providing motor innervation to facial muscles and taste fibers to the anterior two-thirds of the tongue. It is not involved in the ocular muscles.