Brainstem and trigeminal nerve changes after radiosurgery for trigeminal pain.
OBJECTIVE
To evaluate the significance of radiological changes on follow-up MRIs after SRS for TN.


METHODS
Thirty-seven patients with follow-up MRI because of paresthesias, bilateral treatment, or failure were analyzed regarding pain outcome and complications. Mean age was 64.4 years; 14 underwent previous treatment. Twenty-nine had ETN, 5 secondary TN due to tumor or multiple sclerosis, and 3 had atypical TN. Ninety gray was prescribed for 20 patients, 70 Gy for 5, and 80/85 Gy for 2. A 5-mm collimator was used in 32 (88.9%) cases. Mean follow-up was 15 months (range, 4-52 months).


RESULTS
Excellent/good pain relief was sustained in 67% of cases at 13 months' follow-up. Enhancement on MRIs was observed in 21 cases (56.75%) with nerve enhancement in 9, pons enhancement in 4, pons-nerve enhancement in 4, and tumor enhancement in 4. Magnetic resonance images were unremarkable in 16 cases. Pain recurred in 4 cases (5.5-10 months). Pons enhancement correlated with pain relief (P = .0087) but not with nerve enhancement (P = .22). Incidence of slight paresthesias was 66.6%. No anesthesia dolorosa or ophthalmologic problems were observed. Paresthesias correlated with enhancement (P = .02), but not with brainstem volume encompassed by the 20%, 30%, and 50% isodoseline (P = .689, .525, .908). Enhancement free probability at 12 months was 48.5% (Kaplan-Meier).


CONCLUSIONS
Pons enhancement seems to be prognostic for pain relief without higher incidence of complications. Pons volume irradiated did not predict enhancement occurrence. Radiation delivery to the brainstem-REZ interface seems to improve pain outcome, although more paresthesias should be expected.
Gorgulho
Alessandra
A
Division of Neurosurgery, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, USA.
De Salles
Antonio A F
AA
McArthur
David
D
Agazaryan
Nzhde
N
Medin
Paul
P
Solberg
Timothy
T
Mattozo
Carlos
C
Ford
Judith
J
Lee
Steve
S
Selch
Michael T
MT
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001933:Brain Stem / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010292:Paresthesia / Q000453:epidemiology; D016634:Radiosurgery / Q000009:adverse effects; D016896:Treatment Outcome; D014276:Trigeminal Nerve / Q000473:pathology*; D014277:Trigeminal Neuralgia / Q000473:pathology* / Q000601:surgery*