Facial Sensory Restoration After Trigeminal Sensory Rhizotomy by Collateral Sprouting From the Occipital Nerves

Abstract

Lesioning procedures are effective for trigeminal neuralgia (TN), but late pain recurrence associated with sensory recovery is common. We report a case of recurrence of type 1A TN and recovery of facial sensory function after trigeminal rhizotomy associated with collateral sprouting from upper cervical spinal nerves. A 41-yr-old woman presented 2 yr after open left trigeminal sensory rhizotomy for TN with pain-free anesthesia in the entire left trigeminal nerve distribution. Over 18 mo, she developed gradual recovery of facial sensation migrating anteromedially from the occipital region, eventually extending to the midpupillary line across the distribution of all trigeminal nerve branches. She reported recurrence of her triggered lancinating TN pain isolated to the area of recovered sensation with no pain in anesthetic areas. Nerve ultrasound demonstrated enlargement of ipsilateral greater and lesser occipital nerves, and occipital nerve block restored facial anesthesia and resolved her pain, indicating that recovered facial sensation was provided exclusively by the upper cervical spinal nerves. She underwent C2/C3 ganglionectomy, and ganglia were observed to be hypertrophic. Postoperatively, trigeminal anesthesia was restored with complete resolution of pain that persisted at 12-mo follow-up. This is the first documented case of a spinal nerve innervating a cranial dermatome by collateral sprouting after cranial nerve injury. The fact that typical TN pain can occur even when sensation is mediated by spinal nerves suggests that the disorder can be centrally mediated and late failure after lesioning procedures may result from maladaptive reinnervation.