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Show EDITORIAL Surgery for Idiopathic Intracranial Hypertension Paul W. Brazis, MD I diopathic intracranial hypertension ( IIH), a condition in which the intracranial pressure rises without explanation, is usually successfully treated with weight reduction or medications designed to reduce intracranial pressure. However, there are instances when surgical intervention, consisting usually of lumboperitoneal shunt ( LPS), ventriculoperitoneal shunt ( VPS), or optic nerve sheath fenestration ( ONSF), is indicated. Dural venous sinus stenting has also been successfully used in some patients ( 1- 7). In this issue of the Journal of Neuro- Ophthalmology, Wilkes and Siatkowski ( 8) report a patient with IIH whose vision deteriorated after medical therapy and ONSF and perhaps even after VPS. The authors caution that patients who appear to have further visual loss after ONSF should be considered promptly for VPS. Also in this issue, Gellrich et al ( 9) report experimental evidence that ONSF may cause a significant reduction in the number and size of retinal ganglion cells and amacrine cells in rats. On that basis, they caution clinicians against using ONSF. Yet there is extensive anecdotal evidence that ONSF and shunt procedures seem to arrest and sometimes even reverse optic neuropathy in IIH. Whether one type of procedure is more effective than the other is unknown, as no trial has ever compared them. I will summarize the evidence, such as it is. LUMBOPERITONEAL SHUNT LPS has reversed or prevented visual loss in IIH but carries a high rate of shunt-related complications ( 10- 17). In a retrospective study of 27 patients ( 12), LPS was successful in alleviating symptoms in all patients. No patient with a functioning shunt complained of shunt- related symptoms. Among 30 patients who underwent LPS ( 11), 14 had impaired visual acuity preoperatively and 71% improved by at least 2 Snellen lines. Worsening of vision occurred in only 1 eye. Of 28 eyes with abnormal Goldmann perimetry, 64% improved and none worsened. The incidence of serious complications was low, but the major drawback was that 30 patients underwent a total of 126 revisions with a mean revision rate of 4.2 per patient. Departments of Neurology and Ophthalmology, Mayo Clinic- Jacksonville Jacksonville, Florida. Address correspondence to Paul W. Brazis, MD, c/ o Mayo Clinic- Jacksonville, 4500 San Pablo Road, Jacksonville, FL 32224; E- mail: brazis. paul@ mayo. edu J Neuro- Ophthalmol, Vol. 29, No. 4, 2009 271 The need for frequent shunt revisions occurred in a study of 37 patients who underwent 73 LPS and 10 VPS procedures in 6 institutions ( 16), in which only 14 patients remained ‘‘ cured'' after a single surgical procedure. The average time between shunt insertion and shunt replace-ment was 9 months, but 64% of the shunts lasted less than 6 months. Recurrent papilledema or increased cerebro-spinal fluid pressure on lumbar puncture ( 55%) and low- pressure headaches ( 21%) were the most common indications for reoperation. Other reasons were infection, abdominal pain, radicular pain, operative complications, and cerebrospinal fluid leak. The vision of most patients improved or stabilized postoperatively. However, 3 patients who had initially improved subsequently lost vision, 6 had a postoperative decrease in vision, 2 patients improved in 1 eye but worsened postoperatively in the other eye, and 4 lost vision despite apparently adequate shunt function. Shunt failure with relapse of IIH occurred as late as 7 years after insertion. Another study ( 13) found that 36 patients who underwent LPS required 85 shunting procedures with an overall complication rate of 52% and a failure rate of 48%. Taking into full account the reported literature on LPS in IIH, shunt failure appears to be common ( cumulative risk 37%), but most failures occur within 2- 3 months of the initial procedure and only rarely is the first revision required more than 1 year after the initial procedure ( 12). LPS failure can apparently be successfully treated by repeat LPS or by ONSF ( see below). VENTRICULOPERITONEAL SHUNT ( VPS) VPS also appears to be effective in controlling IIH and may have fewer complications than LPS. Among 21 consecutive patients who received LPS and 21 who received VPS with frameless stereotactic image guidance ( 18), there was a 2.5- fold increased risk of shunt revision and a 2.8- fold increased risk of shunt obstruction in LPS. However, LPS and VPS had a similar risk of overdrainage, distal catheter migration, and shunt infection. This first comparison of stereotactic VPS and LPS suggests that VPS placed with image- guided stereotaxy is associated with a lower risk of shunt obstruction and revision. Among 17 patients treated with VPS for IIH and followed for up to 12.8 years ( mean 6.5 years) ( 19), VPS was effective for all clinical manifestations of IIH. Seven patients required 1 or 2 ( a total of 9) surgical revisions, all within the first 1.9 years ( mean of 6 months) of shunt placement. One revision was needed because of malposi-tion of the ventricular catheter, 6 because of failure of the peritoneal catheter, and 2 because of suspected shunt infection. The survival time of the most recent shunt placed in each patient was 1.8- 12.8 years ( mean 6.3 years). Four patients developed low- pressure headache due to over-drainage, a problem resolved by increasing the opening pressure of the valve. However, VPS shunt failure was common in a report of 21 patients who underwent 32 ventricular shunting procedures ( 20 VPS, 10 ventriculoatrial, and 2 ventricu-lopleural) for IIH ( 20). Although all patients experienced relief of headache, 10% of VPSs failed at 3 months after insertion, 20% by 6 months, 50% by 12 months, and 60% by 24 months. Shunt revision was due to distal obstruction in 67%, overdrainage in 20%, and distal catheter migration or CSF leak in 6.5%. In a review of 9 VPS cases ( 21), 6 patients required 9 shunt revisions because of infection in 5, valve dysfunction in 2, distal obstruction in 1, and ventricular catheter malpositioning in 1. Despite the apparently frequent problems with CSF shunts, they are being placed more frequently for IIH in the United States ( 22), perhaps because their efficacy is being recognized. VPS is supplanting LPS because revisions are required less often, shunt obstructions occur less often, and low pressure headache may be controlled by the program-mable shunt. At the Jacksonville Mayo Clinic, we have shifted to doing stereotactic VPS instead of LPS for IIH. OPTIC NERVE SHEATH FENESTRATION ONSF has also been reported to prevent deterioration of vision and, in some cases, improve visual function in patients with IIH ( 23- 35). In a study of 28 patients who underwent 40 ONSFs ( 21), papilledema disappeared or was strikingly reduced in 86% of patients. Visual acuity improved in 30% of eyes, remained stable in 55%, and declined in 15%. However, 10 eyes continued to lose visual acuity or visual field in the postoperative period. In another study of 23 patients ( 29), 91% showed visual improvement postoperatively. Strikingly, more the half of these eyes demonstrated improved visual function in both eyes after unilateral ONSF. ONSF improved vision in 6 patients who failed to recover vision after LPS. In 17 patients with severe visual acuity or field loss from IIH ( 26), ONSF produced improvement or stabiliza-tion of visual acuity in 97%. Among 12 patients whose LPS had failed to control visual loss in another series ( 27), ONSF improved vision in all patients. In a series of 9 patients ( 30), ONSF brought about improvement or stabilization of vision in all but 1 patient. Among 158 ONSFs in 86 patients with IIH ( 36), visual acuity stabilized or improved in 94% of eyes and visual fields stabilized or improved in 88%. ONSF appears to be more effective in preserving visual function when papilledema is not chronic. Among 69 eyes with acute papilledema in one series ( 34), ONSF produced improved visual function in all, but among 272 q 2009 North American Neuro- Ophthalmology Society J Neuro- Ophthalmol, Vol. 29, No. 4, 2009 Editorial 32 eyes with chronic papilledema, only 10 improved ( 34). Moreover, repeat ONSFs were necessary in 13 eyes because of initial failures. The results for ONSF are not uniformly good. In 29 patients in one series ( 25), visual acuity improved in only 14% and worsened in 10%. There were 4 repeat ONSFs in which vision was lost in 1 eye. Long- term follow- up data suggest that ONSF may not be as effective as originally claimed and that up to 33% of patients who show initial improvement in visual function will later show deterioration ( 32,33). Some late failures may be prevented by better and different operative techniques ( 31,33). In a study of 20 eyes of 14 patients ( 11 with idiopathic IIH and 3 with dural venous sinus occlusion) ( 23), visual function improved or stabilized in 17 and deteriorated in 3. Four patients required ONSF despite previous shunting or subtemporal decompression. Two patients required shunting or subtemporal decom-pression after ONSF because of visual failure. No patient lost vision as a direct complication of surgery. Shunting may be successful in preventing further visual loss in eyes whose vision has failed despite ONSF. Among 108 patients who underwent ONSF ( 29), 5 had progressive visual loss afterward. In 1 of these patients, emergency LPS resulted in full visual recovery and in 3 visual loss stabilized. In reviewing the reported literature of patients with IIH in whom ONSF had failed, these authors ( 29) found that 4 of 7 patients sustained no improvement in vision despite various treatments, including shunts. Among 28 patients in another series ( 24), 6 lost vision after ONSF and only 1 had recovery of vision after shunting. Intra-venous corticosteroid treatment appeared to enhance visual recovery in 1 patient whose vision declined after ONSF ( 37). The balance of opinion favors shunt over repeat ONSF if the first ONSF has failed. Persistent complications of ONSF appear to vary widely from one series to another and may be visually damaging. In a series involving ONSF in 86 patients ( 36), diplopia occurred in 30 patients, with 87% resolving spon-taneously. Only 1 eye had permanent severe visual loss from presumed traumatic optic neuropathy. One patient had total ophthalmoplegia and blindness after surgery that com-pletely resolved over 1 month with corticosteroid therapy. Others have reported more dire complications. In a series of 24 patients with IIH who required ONSF ( 35), 44% of eyes had complications including choroidal folds, macular edema, and subretinal hemorrhage, leading to persistent new visual loss in 8 eyes. In a series of 38 eyes ( 38), 15 had postoperative problems including central retinal artery occlusions ( 6%), tonic pupils ( 11%), and temporary ocular duction deficits ( 29%). Eyes that had undergone prior ONSF were more likely to have retinal vascular occlusions ( 67%) than those without a previous operation. Taking account of the reported literature, it appears that approximately one third of patients undergoing ONSF will not experience headache relief and only about 75% of ONSFs appear to be functioning 6 months after surgery, as judged by loss of vision or worsening headache. The probability of an ONSF functioning steadily decreases thereafter, such that 66% are functioning at 12 months, 55% at 3 years, 38% at 5 years, and 16% at 6 years after surgery ( 32). Although patients may be treated with a second ONSF after initial failure, eyes that have more than 1 ONSF are less likely to improve after surgery and are at high risk of retinal vascular occlusion. It is evident that LPS, VPS, and ONSF may improve vision and prevent deterioration of vision in patients with IIH. ( Venous sinus stenting may be effective in selected patients, but the reported literature is too sparse to allow reasonable assessment.) 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