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Introduction
  • 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
  • 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
  • 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
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
 
 

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