title: Trigeminal neuralgia without neurovascular compression presents earlier than trigeminal neuralgia with neurovascular compression.
abstract: OBJECTIVE
  Trigeminal neuralgia (TN) occurs and recurs in the absence of neurovascular compression (NVC). To characterize what may be distinct patient populations, the authors examined age at onset in patients with TN with and without NVC.
  
  
  METHODS
  A retrospective review of patients undergoing posterior fossa surgery for Type I TN at Oregon Health & Science University from 2009 to 2013 was undertaken. Charts were reviewed, and imaging and operative data were collected for patients with and without NVC. Mean, median, and the empirical cumulative distribution of onset age were determined. Statistical analysis was performed using Student t-test, Wilcoxon and Kolmogorov-Smirnoff tests, and Kaplan-Meier analysis. Multivariate analysis was performed using a Cox proportional hazards model.
  
  
  RESULTS
  The charts of 219 patients with TN were reviewed. There were 156 patients who underwent posterior fossa exploration and microvascular decompression or internal neurolysis: 129 patients with NVC and 27 without NVC. Mean age at symptoms onset for patients with and without NVC was 51.1 and 42.6 years, respectively. This difference (8.4 years) was significant (t-test: p = 0.007), with sufficient power to detect an effect size of 8.2 years. Median age between groups with and without NVC was 53.25 and 41.2 years, respectively (p = 0.003). Histogram analysis revealed a bimodal age at onset in patients without NVC, and cumulative distribution of age at onset revealed an earlier presentation of symptoms (p = 0.003) in patients without NVC. Chi-square analysis revealed a trend toward female predominance in patients without NVC, which was not significant (p = 0.08). Multivariate analysis revealed that age at onset was related to NVC but not sex, symptom side or distribution, or patient response to medical treatment.
  
  
  CONCLUSIONS
  NVC is neither sufficient nor necessary for the development of TN. Patients with TN without NVC may represent a distinct population of younger, predominantly female patients. Further research into the pathophysiology underlying this debilitating disease is needed.
authors.affiliation: Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon; and.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Ko
authors.affiliation: Department of Neurological Surgery, University of Indiana, Indianapolis, Indiana.
authors.forename: Albert
authors.initials: A
authors.lastname: Lee
authors.affiliation: Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon; and.
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Raslan
authors.affiliation: Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon; and.
authors.forename: Alp
authors.initials: A
authors.lastname: Ozpinar
authors.affiliation: Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon; and.
authors.forename: Shirley
authors.initials: S
authors.lastname: McCartney
authors.affiliation: Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon; and.
authors.forename: Kim J
authors.initials: KJ
authors.lastname: Burchiel
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003714:Denervation; D005260:Female; D006801:Humans; D008297:Male; D061145:Microvascular Decompression Surgery; D008875:Middle Aged; D009408:Nerve Compression Syndromes / Q000150:complications* / Q000175:diagnosis* / Q000601:surgery; D013997:Time Factors; D016896:Treatment Outcome; D014277:Trigeminal Neuralgia / Q000150:complications* / Q000175:diagnosis* / Q000601:surgery; D055815:Young Adult
keywords: AED = antiepileptic drug; IN = internal neurolysis; MS = multiple sclerosis; MVD = microvascular decompression; NVC = neurovascular compression; OHSU = Oregon Health & Science University; REZ = root entry zone; TN = trigeminal neuralgia; TN-I = Type I TN; TN-II = Type II TN; age at symptom onset; microvascular decompression; neurovascular compression; pain; peripheral nerve; trigeminal neuralgia