Posterior fossa decompression for life-threatening tonsillar herniation in patients with Gliomatosis cerebri: Report of three cases

OBJECTIVE AND IMPORTANCE: Gliomatosis cerebri (GC) is a rare type of primary brain tumor that diffusely infiltrates more than two lobes of the brain while the normal cerebral architecture is maintained. To the best of our knowledge, the association between an acquired tonsillar herniation and GC has never been reported. In this article, we describe three patients with progressive gliomatosis of the cerebellar hemispheres who subsequently showed signs and symptoms secondary to tonsillar herniation. Early recognition of this potentially life-threatening complication allowed us to recommend prompt surgical intervention. CLINICAL PRESENTATION: One patient with primary, or Type I, GC presented with suboccipital headaches, and two patients with secondary, or Type II, GC presented with the signs and symptoms of progressive myelopathy. Serial imaging studies demonstrated progressive involvement of the cerebellum, descent of the cerebellar tonsils through the foramen magnum, and cervicomedullary spinal cord compression. INTERVENTION: Once the tonsillar herniation was recognized, all three patients underwent posterior fossa decompression, a cervical laminectomy to the lowest level of the tonsillar herniation, and duraplasty. All three patients experienced immediate improvement in their conditions. CONCLUSION: Early recognition of tonsillar herniation, a possibly overlooked cause of death in patients with GC, allows for early surgical intervention as a potentially lifesaving procedure and significant improvement in the patient's condition.