Gamma Knife Radiosurgery for Trigeminal Neuralgia Associated with Osteogenesis Imperfecta.

Background: Trigeminal neuralgia is a rare feature of basilar impression, a complication of osteochondrodysplasic disorders. Microvascular decompression is difficult in medically refractory cases. Gamma knife radiosurgery (GKS) is effective for classical trigeminal neuralgia, and we first applied this GKS for a patient suffering from trigeminal neuralgia with basilar impression complicated by osteogenesis imperfecta.

Case Description: An 18-year-old man with type I osteogenesis imperfecta presented with a 2-year history of typical left trigeminal neuralgia affecting the ophthalmic, maxillary, and mandibular nerves. His condition was poorly controlled by carbamazepine and pregabalin. Magnetic resonance imaging confirmed severe basilar impression and an elongated cisternal portion of the left trigeminal nerve. GKS was performed under local anesthesia. The middle part of the cisternal portion of the left trigeminal nerve was chosen as the radiosurgical target, despite the lack of neurovascular compression. The maximum radiosurgical dose was 85 Gy, using a single 4-mm collimator. The patient's trigeminal neuralgia improved by 1 month after GKS, and at 21 months after GKS he remained free of pain and medications.

Conclusions: We report a case of trigeminal neuralgia resulting from severe basilar impression. Conventional microvascular decompression would not have been an appropriate treatment for this patient, so GKS was used. GKS is a simple and effective option even in cases with severe cranial deformity.