Dose and diameter relationships for facial, trigeminal, and acoustic neuropathies following acoustic neuroma radiosurgery.
OBJECTIVE
To define the relationships between dose and tumor diameter for the risks of developing trigeminal, facial, and acoustic neuropathies after acoustic neuroma radiosurgery, a large single-institution experience was analyzed.


METHODS
Two hundred and thirty-eight patients with unilateral acoustic neuromas who underwent Gamma knife radiosurgery between 1987-1994 with 6-91 months of follow-up (median 30 months) were studied. Minimum tumor doses were 12-20 Gy (median 15 Gy). Transverse tumor diameter varied from 0.3-5.5 cm (median 2.1 cm). The relationships of dose and diameter to the development of cranial neuropathies were delineated by multivariate logistic regression.


RESULTS
The development of post-radiosurgery neuropathies affecting cranial nerves V, VII, and VIII were correlated with minimum tumor dose and transverse tumor diameter (P < 0.01 for all except Dmin for VIII where P = 0.10). A comparison of the dose-diameter response curves showed the acoustic nerve to be the most sensitive to doses of 12-16 Gy and the facial nerve to be the least sensitive.


CONCLUSIONS
The risks of developing trigeminal, facial, and acoustic neuropathies following acoustic neuroma radiosurgery can be predicted from the transverse tumor diameter and the minimum tumor dose using models constructed from data presently available.
Flickinger
J C
JC
Department of Radiation Oncology, University of Pittsburgh School of Medicine, PA 15213, USA.
Kondziolka
D
D
Lunsford
L D
LD
D003389:Cranial Nerve Diseases / Q000209:etiology*; D004307:Dose-Response Relationship, Radiation; D005154:Facial Nerve / Q000528:radiation effects*; D005155:Facial Nerve Diseases / Q000209:etiology*; D006801:Humans; D016015:Logistic Models; D015999:Multivariate Analysis; D009464:Neuroma, Acoustic / Q000601:surgery*; D011183:Postoperative Complications; D016634:Radiosurgery / Q000009:adverse effects / Q000295:instrumentation; D011879:Radiotherapy Dosage; D014276:Trigeminal Nerve / Q000528:radiation effects*; D000159:Vestibulocochlear Nerve / Q000528:radiation effects*; D000160:Vestibulocochlear Nerve Diseases / Q000209:etiology*