title: Defining the line between hydromyelia and syringomyelia. A differentiation is possible based on electrophysiological and magnetic resonance imaging studies.
abstract: OBJECTIVE
  With the frequent use of magnetic resonance imaging (MRI), patients with subtle and diffuse symptoms due to small syrinx cavities increasingly present to neurosurgical care. In this respect, a dilated central canal, hydromyelia, must be separated from patients with true syringomyelia with an underlying disorder, as they do not share clinical and radiological features. We hypothesize that a differentiation of these two entities with distinct diagnostic tools is possible.
  
  
  METHODS
  To describe the entity of hydromyelia, we excluded all patients from the syringomyelia database (n = 142) with any obvious cause of a syringomyelia, any objective neurological deficits on clinical examination, pathological results on electrophysiological monitoring (SSEP, MEP, silent periods) or a widening of the spinal cord cavity of more than 6 mm on MRI [routine acquisitions with FLAIR, T1/T2-weighted images, Cine and CISS (constructive interference in steady-state) studies]. Life quality was assessed through SF-36 questionnaires and an individualized questionnaire for the clinical history, pain and alternative therapies.
  
  
  RESULTS
  Forty patients (15 males/25 females) matched the criteria of a hydromyelia. With a mean age of 36.7 years (range 11-62), they almost all presented with pain (79%) or dysaesthesia of the limbs, with some having been an incidental finding (10%). Over a follow-up time of 36.9 months (range 6-93) there was no neurological or radiological deterioration.
  
  
  CONCLUSIONS
  Patients with a hydromyelia do not share clinical or radiological characteristics with patients harbouring a true syringomyelia. As hydromyelia does not represent a disease with an underlying pathology, no clinical or radiological progression has been seen. With sophisticated diagnostic tools to rule out any pathology this subset of patients can be identified.
authors.affiliation: Department of Neurosurgery, University of Tübingen, Hoppe-Seyler-Str. 3, 72076 Tübingen, Germany. f.roser@gmx.de
authors.forename: Florian
authors.initials: F
authors.lastname: Roser
authors.forename: Florian H
authors.initials: FH
authors.lastname: Ebner
authors.forename: Carolin
authors.initials: C
authors.lastname: Sixt
authors.forename: Jennifer Müller V
authors.initials: JM
authors.lastname: Hagen
authors.forename: Marcos S
authors.initials: MS
authors.lastname: Tatagiba
mesh_terms: D000293:Adolescent; D000328:Adult; D002574:Cervical Vertebrae; D002648:Child; D003937:Diagnosis, Differential; D018450:Disease Progression; D004558:Electric Stimulation / Q000379:methods; D004568:Electrodiagnosis / Q000379:methods*; D019054:Evoked Potentials, Motor / Q000502:physiology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology; D010147:Pain Measurement / Q000379:methods; D011788:Quality of Life; D012678:Sensation Disorders / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D013116:Spinal Cord / Q000473:pathology* / Q000503:physiopathology; D011795:Surveys and Questionnaires; D013595:Syringomyelia / Q000175:diagnosis* / Q000503:physiopathology; D013904:Thoracic Vertebrae; D055815:Young Adult