Definitions Definitions syringobulbia a syrinx within the brainstem that leads to neurologic symptoms syringomyelia a syrinx (fluid-filled cavity) within the spinal cord that progressively expands and leads to neurologic deficits Epidemiology syringomyelia incidence prevalence is ~8.4/100,000 demographic men > women usually presents in the 3rd or 4th decade of life Etiology Pathophysiology results from lesions that partially obstruct CSF flow, including: craniocervical junction abnormalities >50% of cases are related to Chiari malformations herniated cerebellar tonsils act as pistons, obstructing the subarachnoid space at the foramen magnum and creating a pressure wave in the subarachnoid space with each heartbeat spinal cord trauma 4-10% of patients with spinal cord injuries may become apparent years after the injury spinal cord tumors 30% of patients with spinal cord tumors develop a syrinx post-infectious (e.g., meningitis) due to scarring from arachnoiditis Associated conditions developmental scoliosis scoliosis occurs in 25-80% of patients with syringomyelia neural axis malformations are found in 1.8-25% of patients initially diagnosed with idiopathic scoliosis, depending on case series and referral patterns Klippel-Feil deformity Charcot joints occur in <5% with syringomyelia often involves the shoulder joint Presentation Syringomyelia symptoms usually begin insidiously between adolescence and 45 y/o occipital headache sometimes exacerbated by the Valsalva maneuver back pain radicular pain neurologic deficits syringomyelia often presents as a central cord syndrome physical exam reflexes asymmetric and/or hyperactive reflexes asymmetric abdominal reflexes asymmetric sweating spasticity motor asymmetric muscle bulk weakness sensory deficits in pain and temperature sensation in a cape-like distribution over the back of the neck, shoulders, and arms light touch and position and vibration sensations are usually not affected deformity lower extremity contractures and deformities scoliosis Syringobulbia symptoms related to cranial nerve involvement tongue weakness and atrophy (CN XII) sternocleidomastoid and trapezius weakness (CN XI) dysphagia and dysarthria (CN IX, CN X) facial palsy (CN VII) Imaging Radiographs relative lack of apical lordosis may indicate the presence of syrinx scoliosis series CT not useful for the characterization of a syrinx, used only to evaluate associated scoliosis MRI diagnosis of a syrinx is made with MRI obtain MRI with gadolinium enhancement to rule out associated tumor indications for MRI in patients with scoliosis: abnormal curve (e.g. double curve, apex left) neurologic deficit infantile or juvenile age at onset male with atypical or large curve thoracic kyphosis >30° Histopathology Gross pathology cavitation of spinal cord gray matter syrinx in continuity with or adjacent to the central canal inner layer of gliotic tissue Differential Diagnosis Hydromyelia Glioependymal cysts Myelomalacia Cystic tumors Persistent central canal Treatment Nonoperative observation indications if asymptomatic, non-enlarging syrinx, most recommend against prophylactic surgery orthopaedic management may include observation or bracing, but results of bracing are mixed Operative decompression of the foramen magnum and upper cervical cord +/- shunting indications cranial nerve deficits extremity motor weakness cerebellar findings sensory deficits technique prior to spinal arthrodesis outcomes effect of decompression on neurologic signs and symptoms is variable, but supported because deficits tend to progress some evidence shows surgery alone may improve spinal deformity scoliosis is still likely to progress in patients with large curves or in children >8 y/o spinal fusion indications depends on the age of presentation and curve characteristics technique timing of orthopaedic intervention is debatable most recommend waiting 3-6 months after surgical decompression Complications In general, same as for idiopathic scoliosis increased risk of neurologic deterioration, including paralysis, if fusion is performed in a patient with an undiagnosed syrinx Prognosis Natural history not well defined prognosis depends on the degree of spinal deformity and severity of neurologic deficits