Long-term effectiveness of optic nerve sheath decompression for pseudotumor cerebri
T. C. Spoor and J. G. McHenry
Department of Ophthalmology, Wayne State University School of Medicine, Detroit, Mich.
OBJECTIVE--To determine the long-term success of optic nerve sheath
decompression in preserving visual function in patients with pseudotumor
cerebri (PTC). DESIGN--To define stability of visual fields, we reviewed 32
series of postoperative visual fields in patients who were undergoing optic
nerve sheath decompression for PTC who had stable visual acuity and four or
more fields during 6 to 60 months of follow-up. The SD of these series was
0.80 dB (+/- 0.39 dB) of mean deviation. Fluctuations within 2 SDs of the
1-month postoperative field were +/- -1.60 dB. We therefore defined
stability as a mean deviation within 2 dB of the preoperative visual field;
improvement, greater than 2-dB mean deviation, and worsening, less than
2-dB mean deviation. We then extended our review to include all patients
(54 patients, 75 eyes) who underwent optic nerve sheath decompression for
PTC, who were followed up with serial automated perimetry (Humphrey 30-2).
RESULTS--Fifty-one eyes (68%) showed improvement (36%) or stabilization
(32%) of visual function. Twenty-four eyes (32%) experienced deterioration
of visual function after an initially successful optic nerve sheath
decompression. The probability of failure from 3 to 5 years was .35 by
life-table analysis. CONCLUSION--Optic nerve sheath decompression
effectively stabilizes or improves visual function in the majority of
patients with PTC and visual loss. However, it may fail at any time after
surgery. Patients with PTC need to be followed up routinely with automated
perimetry to detect deterioration of visual function.
