Clinical course and prognosis of trochlear nerve schwannomas.
OBJECTIVE
To delineate the disease course and prognosis of patients with mass lesions of the fourth nerve presumed to be schwannomas.


METHODS
Nonrandomized retrospective case series.


METHODS
Thirty-seven consecutive cases of presumed trochlear nerve schwannoma from 9 tertiary university neuro-ophthalmology centers.


METHODS
Cases were collected, and their clinical characteristics on presentation and follow-up are described. Inclusion criteria were brain magnetic resonance imaging (MRI) with a lesion suggestive of a schwannoma along the course of the fourth nerve. Exclusion criteria were other causes of fourth nerve palsy, such as congenital, traumatic or microvascular; normal (or lack of) initial brain MRI; lack of adequate clinical information; and disappearance of the lesion on subsequent follow-up brain MRI.


METHODS
Demographics of patients, presence of neurofibromatosis, symptoms on presentation, vertical deviation, lesion size (on presentation and follow-up), length of follow-up, and outcomes of treatment for lesions or diplopia.


RESULTS
Seven patients were excluded and of the 30 patients included in our series, patients were predominantly male (77%) with a mean age of 51 years (range 9-102 years). In contrast with prior case reports, almost all of our cases had a fourth nerve palsy on presentation (29/30), often isolated. Mean follow-up was 3.1 years (range 0.2 months to 11.1 years). There was no significant difference between initial and follow-up lesion size (4.4 vs. 5 mm) for patients who did not receive treatment of lesions (P = 0.36). Only 3 patients underwent neurosurgical resection and an additional patient received gamma-knife radiotherapy. The majority of patients (24/30) did not pursue strabismus surgery for vertical diplopia.


CONCLUSIONS
Patients with isolated fourth nerve palsy and small lesions of the fourth nerve have a good prognosis and should be followed with serial MRI scans without neurosurgical intervention unless they develop signs of brain stem compression. Most patients with diplopia and benign fourth nerve lesions typical of trochlear nerve schwannoma can adapt with either prism spectacles or no treatment at all, although strabismus surgery can be successful.
Elmalem
Valerie I
VI
Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA 30322, USA.
Younge
Brian R
BR
Biousse
Valérie
V
Leavitt
Jacqueline A
JA
Moster
Mark L
ML
Warner
Judith
J
Kupersmith
Mark J
MJ
Landau
Klara
K
Brodsky
Michael C
MC
Frohman
Larry P
LP
May
Eugene F
EF
Tomsak
Robert L
RL
Newman
Nancy J
NJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003390:Cranial Nerve Neoplasms / Q000473:pathology* / Q000628:therapy; D004172:Diplopia / Q000175:diagnosis; D005139:Eyeglasses; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009442:Neurilemmoma / Q000473:pathology* / Q000628:therapy; D011379:Prognosis; D016634:Radiosurgery; D012189:Retrospective Studies; D020432:Trochlear Nerve Diseases / Q000473:pathology* / Q000628:therapy