Stereotactic radiosurgical pallidotomy and thalamotomy with the gamma knife: MR imaging findings with clinical correlation--preliminary experience.
OBJECTIVE
To evaluate the temporal evolution and appearance of a radiosurgical lesion at magnetic resonance (MR) imaging and the clinical response in patients undergoing stereotactic radiosurgical pallidotomy or thalamotomy with the gamma knife.


METHODS
Seventeen patients with medically refractory movement disorders underwent stereotactic radiosurgical pallidotomy (n = 2) or thalamotomy (n = 15). A single dose of 120-140 Gy was administered to a target in the globus pallidus interna or ventralis intermedius thalamic nucleus. Postprocedure gadolinium-enhanced MR imaging and clinical assessment were performed at 1 month and 3 months.


RESULTS
At 3 months, the radiosurgical lesion most commonly (n = 11) appeared as a ring-enhancing focus 5 mm or less in diameter surrounded by vasogenic edema that extended less than 7 mm in radius beyond the target. Five patients had ring-enhancing lesions 7 mm or more in diameter; four of these developed symptomatic perilesional edema at 3 (n = 2) or 8 (n = 2) months after the procedure. Onset of therapeutic effect began approximately 4 weeks after treatment. In the 15 patients with tremor, there was a mean decline of 2.1 on the Tremor Rating Scale.


CONCLUSIONS
Findings in this pilot study suggest that radiosurgical thalamotomy is a promising treatment for medically refractory tremor. Three-month follow-up MR studies show a ring-enhancing lesion surrounded by a variable amount of vasogenic edema. Visualization of the radiosurgical lesion and the clinical response are delayed compared to that with radio-frequency procedures.
Department of Radiology, Wills Eye Hospital, Philadelphia, PA, USA. friedm11@jeflin.tju.edu
D P
DP
Friedman
H W
HW
Goldman
A E
AE
Flanders
S M
SM
Gollomp
W J
WJ
Curran
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001929:Brain Edema / Q000175:diagnosis; D001931:Brain Mapping; D005260:Female; D005917:Globus Pallidus / Q000473:pathology / Q000601:surgery*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination; D010300:Parkinson Disease / Q000175:diagnosis / Q000601:surgery*; D011183:Postoperative Complications / Q000175:diagnosis*; D016634:Radiosurgery; D013238:Stereotaxic Techniques; D013787:Thalamic Nuclei / Q000473:pathology / Q000601:surgery*; D016896:Treatment Outcome; D014202:Tremor / Q000175:diagnosis / Q000601:surgery*