Definitions Definitions syringomyelia a syrinx (fluid filled cavity) within the spinal cord that progressively expands and leads to neurologic deficits syringobulbia a syrinx within the brain stem that leads to neurologic symptoms Epidemiology Synringomyelia incidence prevalence of the disease is about 8.4 cases per 100,000 people demographic occurs more frequently in men than in women usually appears in the third or fourth decade of life Etiology Pathophysiology usually result from lesions that partially obstruct CSF flow including craniocervical junction abnormalities more than 50% related to Chiari malformations (CM) herniated cerebellar tonsils act as pistons obstructing subarachnoid space at foramen magnum creating pressure wave in subarachnoid space with each heartbeat spinal cord trauma found in 4-10% of patients with spinal cord injury may become apparent years after the injury spinal cord tumors 30% of patients with a spinal cord tumor develop a syrinx post-infectious (e.g. meningitis) due to scarring from arachnoiditis Associated conditions developmental scoliosis 25% to 80% of cases of syringomyelia may have scoliosis neural axis malformations found in 1.8% to 25% of patients initially diagnosed with idiopathic scoliosis depending on case series and referral patterns Klippel-Feil deformity Charcot's joints occurs in < 5% with syringomyelia often involves shoulder joint Presentation Syringomyelia symptoms symptoms usually begin insidiously between adolescence and age 45 occipital headache sometimes exacerbated by Valsalva maneuver back pain radicular pain neurologic deficits syringomyelia often presents with a central cord syndrome physical exam reflexes asymmetric abdominal reflexes asymmetric and/or hyperactive reflexes asymmetric sweating spasticity motor asymmetric muscle bulk weakness sensory deficits in pain and temperature sensation in a capelike distribution over the back of the neck light touch and position and vibration sensation are usually not affected deformity lower extremity contracture and deformity scoliosis Syringobulbia symptoms related to cranial nerve involvment tongue weakness and atrophy (CN XII) sternocleidomastoid & trapezius weakness (CN XI) dysphagia and dysarthia (CN IX, CN X) facial palsy (CN VII) Imaging Radiographs relative lack of apical lordosis may indicate presence of syrinx scoliosis series for evaluation of scoliosis CT not applicable for characterization of syrinx, only for associated scoliosis MRI diagnosis of syrinx made by 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 gender with atypical or large curve thoracic kyphosis >30 degrees Histopathology Gross pathology cavitation of spinal cord gray matter syrinx in continuity with or adjacent to 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-elarging syrinx, most pediatric neurosurgeons recommend against prophylactic surgery orthopaedic management may include observation or bracing during neurosurgical and neurologic evaluations but results of bracing mixed Operative decompression of the foramen magnum and upper cervical cord +/- shunting indications cranial nerve deficits extremity motor weakness cerebellar findings sensory deficit technique done prior to spinal arthrodesis outcomes effect of decompression on neurologic signs and symptoms is variable but supported due to propensity of deficits to progess some evidence shows neurosurgery alone may improve spinal deformity but scoliosis still likely to progress in large curves or children >8 years old spinal fusion indications depends on age of presentation and curve characteristics technique timing of orthopaedic intervention debatable most recommend waiting 3 to 6 months after neurosurgical decompression Complications In general, same as for idiopathic scoliosis Increased risk of neurologic deterioration including paralysis if fusion done with undiagnosed syrinx Prognosis Natural history not well defined prognosis depends on degree of spinal deformity and neurologic deficits multiple authors report resolution or improvement in syrinx size and neurologic deficits