title: Persistent trigeminal neuralgia after removal of contralateral posterior cranial fossa tumor. Report of two cases.
abstract: BACKGROUND
  Contralateral trigeminal neuralgia as a false localizing sign in patients with posterior cranial fossa tumors is rare. Persistent contralateral trigeminal neuralgia after removal of the posterior fossa expanding lesion with microsurgical exploration of the affected trigeminal nerve root has been described in only a few reports. Displacement of the brainstem and the trigeminal nerve root, arachnoid adhesions, and vascular compression of the nerve root entry zone have been reported as causes of persistent contralateral trigeminal neuralgia.
  
  
  METHODS
  One patient developed transformation of the contralateral constant burning facial pain into trigeminal neuralgia after removal of a posterior fossa meningioma. A typical right-sided tic douloureux in our second patient did not disappear after removal of a left acoustic neurinoma. CT scan revealed brainstem displacement to the side of trigeminal neuralgia. Microsurgical exploration in both cases demonstrated the squeezed and distorted trigeminal nerve root and displaced brain stem with no vascular involvement. Both patients underwent partial trigeminal rhizotomy for pain control.
  
  
  RESULTS
  Complete disappearance of the trigeminal neuralgia was evident in both cases with postoperative facial sensory loss. The postoperative course in the first case was uneventful; the second patient died from purulent meningoencephalitis.
  
  
  CONCLUSIONS
  Persistent contralateral trigeminal neuralgia after removal of a posterior fossa tumor is caused by distortion of the fifth nerve root by the displaced brainstem. Partial trigeminal rhizotomy can be performed for alleviation of facial neuralgic pain in cases without neurovascular compression.
authors.affiliation: Department of Neurosurgery, Russian Medical Academy of Postgraduate Education, Botkin Hospital, Moscow.
authors.forename: Y A
authors.initials: YA
authors.lastname: Grigoryan
authors.forename: C V
authors.initials: CV
authors.lastname: Onopchenko
mesh_terms: D000368:Aged; D003388:Cranial Fossa, Posterior; D003399:Craniotomy / Q000009:adverse effects*; D017809:Fatal Outcome; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008590:Meningoencephalitis / Q000209:etiology; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000601:surgery*; D019051:Rhizotomy / Q000009:adverse effects; D019292:Skull Base Neoplasms / Q000601:surgery*; D013492:Suppuration; D014057:Tomography, X-Ray Computed; D014277:Trigeminal Neuralgia / Q000209:etiology* / Q000601:surgery