Role of vitamin A metabolism in IIH: Results from the idiopathic intracranial hypertension treatment trial.

INTRODUCTION: Vitamin A and its metabolites (called retinoids) have been thought to play a role in the development of idiopathic intracranial hypertension (IIH). The IIH Treatment Trial (IIHTT) showed the efficacy of acetazolamide (ACZ) in improving visual field function, papilledema grade, quality of life and cerebrospinal fluid (CSF) pressure. We postulated that IIH patients would demonstrate elevated measures of vitamin A metabolites in the serum and CSF. METHODS: Comprehensive measures of serum vitamin A and its metabolites were obtained from 96 IIHTT subjects, randomly assigned to treatment with ACZ or placebo, and 25 controls with similar gender, age and body mass index (BMI). These included retinol, retinol binding protein, all-trans retinoic acid (ATRA), alpha- and beta-carotenes, and beta-cryptoxanthin. The IIHTT subjects also had CSF and serum vitamin A and metabolite measurements obtained at study entry and at six months. RESULTS: At study entry, of the vitamin A metabolites only serum ATRA was significantly different in IIHTT subjects (median 4.33nM) and controls (median 5.04nM, p=0.02). The BMI of IIHTT subjects showed mild significant negative correlations with serum ATRA, alpha- and beta-carotene, and beta-cryptoxanthin. In contrast, the control subject BMI correlated only with serum ATRA. At six months, the serum retinol, alpha-carotene, beta-carotene, and CSF retinol were increased from baseline in the ACZ treated group, but only increases in alpha-carotene (p=0.02) and CSF ATRA (p=0.04) were significantly greater in the ACZ group compared with the placebo group. No other vitamin A measures were significantly altered over the six months in either treatment group. Weight loss correlated with only with the change in serum beta-carotene (r=-0.44, p=0.006) and the change in CSF retinol (r=-0.61, p=0.02). CONCLUSION: Vitamin A toxicity is unlikely a contributory factor in the causation of IIH. Our findings differ from those of prior reports in part because of our use of more accurate quantitative methods and measuring vitamin A metabolites in both serum and CSF. ACZ may alter retinoid metabolism in IIH patients.

Cortical blindness, transient and otherwise, associated with detachable coil embolization of intracranial aneurysms.

BACKGROUND AND PURPOSE: Cortical visual loss is a rare complication of cerebral angiography without a definitive pathophysiology. Given the rapid increase in endovascular procedures used to treat cerebral aneurysms, we explored the prevalence of this complication and whether we could add to the understanding of this disorder. MATERIALS AND METHODS: We performed a retrospective review of all procedures performed with the same contrast agent and detachable coils for treatment of posterior circulation aneurysms by 1 endovascular surgery service from 1996 to 2006. All patients were evaluated before and after each procedure by a team that included a neuro-ophthalmologist. RESULTS: Of 137 intra-arterial treatment procedures performed for posterior circulation aneurysms, we identified 4 patients with cerebral vision loss complications. During the same time period, >500 aneurysms of the anterior cerebral circulation were treated without this complication. The visual field loss was unilateral in 2 and bilateral in 2 patients. Recovery was complete in 3 and almost normal in the fourth patient. The amount of contrast used and the duration of the procedure were similar among all patients. The 4 patients had no identified specific risk factors for developing procedure-associated occipital dysfunction, all 4 had undergone prior angiography, and 1 patient had undergone repeat coiling, without complication. CONCLUSION: The 2.9% prevalence of cerebral visual loss with endovascular coil treatment of posterior circulation aneurysms is higher than that for angiography alone. Our patients recovered well with corticosteroid and intravenous hydration treatment. Recognizing the self-limiting nature of this problem might prevent an unneeded intervention.

Visual function at baseline and 1 month in acute optic neuritis: predictors of visual outcome.

OBJECTIVE: To identify cutpoints for visual measures at baseline and 1 month predictive of abnormal 6-month vision that could be used as eligibility criteria in a clinical trial to test potential neuroprotection or myelin repair agents in patients with optic neuritis. To determine whether moderate-to-severe dysfunction in one or more visual measures at baseline or 1 month correlates with having major vision loss at 6 months. METHODS: We used the Optic Neuritis Treatment Trial database to evaluate various cutpoints for baseline and 1-month vision levels that predicted abnormal 6-month vision. For selected cutpoints, we computed a 95% CI for positive predictive value and the required sample size if the cutpoint was to be used for clinical trial eligibility. We evaluated whether the degree of visual loss at baseline, 1 month, or change in visual function from baseline to 1 month correlated with 6-month visual acuity, contrast sensitivity, or threshold visual field. RESULTS: The best cutpoints for baseline and 1 month were visual acuity

Treatment of cerebral aneurysms with hydrogel-coated platinum coils (HydroCoil): early single-center experience.

PURPOSE: The authors report their experience using HydroCoils in the treatment of cerebral aneurysms. METHODS: We performed a retrospective review of the first 100 nonrandomized patients (104 coiled saccular cerebral aneurysms) treated with HydroCoils during a 27-month period. RESULTS: The average percentage of HydroCoil by length detached in treated aneurysms was 45.5% (range, 9.9-100%). Immediate postprocedure angiography demonstrated complete aneurysm occlusion in 34%, neck remnant in 35%, and incomplete occlusion in 32%. Immediate procedure-related morbidity and mortality rates were 5.8% and 0%, respectively. Angiographic follow-up was obtained in 51% (51/100 patients; 53/104 aneurysms; average, 10.3 months; range, 0-31 months). In these 53 angiographically followed aneurysms, the overall recanalization rate was 21%: no recanalization occurred in 23 aneurysms with small size (<10 mm)/small neck (<4 mm) (S/S); 4 recanalizations occurred in 7 aneurysms with small size/wide neck (>4 mm) (S/W); 6 recanalizations (27%) occurred in 22 large (L) aneurysms (>10-25 mm, 70% angiographic follow-up); and 1 giant (G) (>25 mm) aneurysm recanalized. A large proportion of aneurysms that were not initially completely occluded were completely occluded on follow-up (15/43 [35%]). Clinical follow-up was obtained in 73 patients (73%; average, 5.3 months; range, 0-24 months): 93% of these patients were neurologically improved or unchanged. Three patients rehemorrhaged and 3 patients with unruptured aneurysms developed delayed hydrocephalus. CONCLUSIONS: The overall safety profile of HydroCoils appears acceptable. Preliminary midterm observations suggest less coil compaction/aneurysm recanalization in large aneurysms. However, HydroCoil-related delayed hydrocephalus is a concern.

Clinical profile of simultaneous bilateral optic neuritis in adults.

AIM: To establish the clinical profile of simultaneous bilateral optic neuritis in adults, the efficacy of steroid therapy, extent of visual recovery, and neurological outcome. METHODS: The authors performed a retrospective review of records of patients referred to a neuro-ophthalmology service with acute bilateral optic neuritis from 2000-4. Exclusion criteria included previous multiple sclerosis or myelopathy, known systemic disorders or medications associated with optic neuropathy, uveitis, or neoplasm. Patients received intravenous methylprednisolone followed by oral prednisone. Visual acuity (logMAR conversion), mean deviation (dB) for visual fields, percentage of Ishihara plates seen, ophthalmoscopy, and neurological evaluation were recorded at baseline and at 6 months or 12 months. Owing to strong correlation for visual loss between eyes, the results for the worse eye in each patient were analysed. RESULTS: 11 men and four women, with an age range of 18-64 years, had bilateral decreased vision, 12 with pain on eye movement. Except for one patient, no aetiology was found. All patients had normal neurological evaluations, average visual acuity 1.71 (SD 0.55), colour vision 2.7% (SD 9.9%), and mean deviation -25.35 dB (SD -7.95 dB). Both optic nerves showed abnormal signal on magnetic resonance imaging. 14 patients improved and their last average visual acuity, colour vision, and mean deviation were 0.36 (SD 0.54), 69% (SD 46%), and -7.05 dB (SD 8.40 dB), respectively. No patient developed a neurological problem during the follow up with a mean of 11 months. CONCLUSION: Idiopathic acute bilateral optic neuritis without myelopathy occasionally occurs in adults. Vision recovers with corticosteroid therapy and during the first year neurological dysfunction will frequently not occur.

Ocular motor dysfunction and ptosis in ocular myasthenia gravis: effects of treatment.

AIM: The optimal treatment of ocular myasthenia gravis (OMG) remains unknown. The authors evaluated the efficacy of prednisone and pyridostigmine in reducing diplopia, ocular motor dysfunction, and ptosis in patients with OMG. METHODS: Review of records from a clinical database from one neuro-ophthalmology service of patients presenting with OMG between 1990 and 2002, excluding those who developed generalised MG within the first month after diagnosis. Institutional review board approval was obtained for this study. PARTICIPANTS/INTERVENTIONS: Non-randomised, unmasked, therapy was given. 55 patients with diplopia in primary or downward gaze and clinically demonstrable extraocular muscle dysfunction received prednisone. 34 patients who had contraindications to steroids or who refused treatment with prednisone received pyridostigmine only. Over 5 days the daily prednisone dose was increased to 50-60 mg and then gradually reduced to 10 mg, followed by further reduction as tolerated. The pyridostigmine dose was begun at 180 mg daily and increased as tolerated. MAIN OUTCOME MEASURES: Follow up evaluations, performed at 1, 3-6, 12, and 24 months, detailed the frequency of ptosis and diplopia and the amount of ocular motor deviation in primary and downward gaze. RESULTS: The prednisone and pyridostigmine groups were similar for age, sex, acetylcholine receptor antibody level, prism cover test results for primary and downward gaze, diplopia in primary and downward gaze, and unilateral ptosis. Bilateral ptosis was present in 32.4% of the pyridostigmine group and 10.9% of the prednisone group (p = 0.02). The prednisone group showed resolution in primary gaze diplopia, downgaze diplopia, unilateral ptosis, and bilateral ptosis in 73.5%, 75.5%, 85.7%, and 98%, respectively at 1 month. The benefit persisted at 3-6, 12, and 24 months except for the bilateral ptosis. The pyridostigmine group showed resolution in primary gaze diplopia, downgaze diplopia, unilateral ptosis, and bilateral ptosis in 6.9%, 17.2%, 50%, and 76.7% of patients after 1 month of treatment. The prism cover results improved (p = 0.003) in the prednisone group only. In the prednisone group, four patients had no response to therapy. Among the 51 prednisone responsive patients, there were 33 recurrences in 26 patients. 12 patients, all prednisone treated, had remissions. Except for three patients who developed diabetes, no patient developed a clinically significant systemic corticosteroid complication. CONCLUSION: These results suggest that 50-60 mg daily prednisone followed by lower doses (10 mg or less) has the benefit of resolving ptosis and diplopia that lasts for at least 2 years in approximately 70% of patients.

Idiopathic hypertrophic pachymeningitis.

BACKGROUND: Hypertrophic pachymeningitis is an uncommon disorder that causes a localized or diffuse thickening of the dura mater and has been associated with rheumatoid arthritis, syphilis, Wegener's granulomatosis, tuberculosis, and cancer. Few series of the idiopathic variety have been described, particularly with respect to MRI correlation to clinical outcome and treatment. OBJECTIVE: To investigate the clinical and laboratory evaluation, course, and treatment of patients with idiopathic hypertrophic pachymeningitis (IHP), to correlate the MRI findings with the clinical course, and to review the literature on IHP. METHODS: Retrospective case series of 12 patients (9 men, 3 women), with a mean age of 55 years (range 39 to 88 years), who had IHP by imaging studies, meningeal or orbital biopsy, or both. The clinical features, laboratory evaluation, contrast-enhanced MRI, treatment, and clinical outcome were documented for each case. The mean duration of follow-up was 3.5 years (range 3 months to 16 years). RESULTS: The main clinical features at presentation were headache (11 cases), loss of vision (7 cases), diplopia (4 cases), papilledema (2 cases), other cranial nerve involvement (3 cases), ataxia (2 cases), and seizures (1 case). On the initial MRI, the location of abnormal enhancement of the dura mater correlated with the clinical findings and the sphenoid wing area was affected in all patients. The sedimentation rate was elevated in five cases. The CSF had increased protein in six cases and lymphocytosis in four cases. Biopsy of the dura mater in five cases and the orbital soft tissue in one case showed infiltrates of small mature lymphocytes, plasma cells, and epithelioid histiocytes, but no neoplasia, vasculitis, or infectious agents. Cultures of the CSF and biopsy material remained sterile. Corticosteroid therapy improved the vision in 7 of 8 cases and controlled headache in 10 of 11 cases. Five cases had partial improvement of other neurologic symptoms and signs. Recurrence developed with steroid tapering in six cases. One case had progressive deterioration and died. In four cases methotrexate or azathioprine was added with reduction of the steroid dose. Follow-up MRI performed in 11 patients correlated 80% with the clinical state (p = 0.01). CONCLUSION: IHP can be suspected on MRI and defined pathologically on biopsy. Untreated, the clinical course is usually marked by severe headache and progressive neurologic deterioration and vision loss. Although initially steroid-responsive, clinical manifestations frequently recur with corticosteroid taper, requiring the addition of immunosuppressive agents in some cases.

Bilateral orbital signs predict cortical venous drainage in cavernous sinus dural AVMs.

BACKGROUND: Most cavernous sinus dural arteriovenous malformations (CSdAVM) have a benign clinical course. Those CSdAVM that drain into cortical veins have an increased risk for neurologic complications. OBJECTIVE: To find whether a specific clinical sign predicts cortical venous drainage (CVD) in CSdAVM. METHODS: The records of 118 patients with CSdAVM were evaluated for the clinical features of the disorder and tested for predictive value of CVD demonstrated angiographically or suggested by MRI using logistic regression and odds ratio (OR) analysis. RESULTS: Clinical signs that predicted the presence of CVD included bilateral orbital signs (p = 0.004, OR = 23.84) and presence of a postauricular bruit (p = 0.035, OR = 23.8). No other clinical sign predicted the presence of CVD, including extraocular muscle dysfunction, abducens or oculomotor dysfunction, increased intraocular pressure, venous stasis retinopathy, choroidal effusion, optic neuropathy, subjective bruit, and objective orbital bruit. CONCLUSION: Patients who present with or develop bilateral orbital congestion should be recognized as being at increased risk for CVD.

Unilateral swollen disc due to increased intracranial pressure.

Truly unilateral papilledema is rare and poses a diagnostic problem. The authors have prospectively looked for patients with truly unilateral papilledema and found 15 patients, 10 of whom had idiopathic intracranial hypertension. Neuroimaging did not indicate a reason for the lack of swelling in the other nerve. The visual deficits and outcomes were similar to those of patients with bilateral papilledema. Although monocular papilledema is uncommon, a lumbar puncture with opening pressure measurement should be considered.

Natural history of brainstem cavernous malformations.

OBJECTIVE: To review the natural history and determine the rates of intra- and extralesional hemorrhaging of brainstem cavernous malformations (cavernomas) monitored by one neuro-ophthalmology service. METHODS: A record review of all patients with brainstem cavernomas who were evaluated by a neuroophthalmology service between 1987 and 1999 was performed. We recorded the clinical symptoms and Rankin disability grade at presentation, during the worst clinical episode, and at the last follow-up examination. Magnetic resonance imaging scans were reviewed for evidence of intralesional hemorrhage (a bleeding episode), edema, or venous anomalies, and the cavernoma size was assessed. RESULTS: Thirty-seven patients (age range, 6-73 yr; mean age at presentation, 37.5 yr) underwent a mean of 4.9 years of follow-up monitoring. At presentation, there were 27 bleeding events and 8 nonhemorrhagic events; 2 patients did not exhibit symptoms. Patients who were at least 35 years of age exhibited a lower risk of bleeding episodes (odds ratio, 0.15; 95% confidence interval, 0.1-0.4). Cavernomas of at least 10 mm were associated with a higher risk of bleeding episodes (odds ratio, 3.48; 95% confidence interval, 1.3-9.4). Thirty-nine bleeding episodes occurred in 31 patients, yielding a bleeding rate of 2.46%/yr. There were eight rebleeding episodes, yielding a rebleeding rate of 5.1%/yr. Three patients experienced extralesional bleeding episodes; all of these patients experienced rebleeding. Of the 39 follow-up magnetic resonance imaging scans, the cavernoma size was unchanged in 66.7%, smaller in 18%, and larger in 15%. At the last follow-up examination, the mean Rankin grade was 1.0 for all patients, 0.6 for the 25 nonsurgically treated patients, and 1.4 for the 12 surgically treated patients. CONCLUSION: Rebleeding is not more common among patients who first present with bleeding, and it often has little effect on the neurological status of patients. Significant morbidity attributable to a brainstem cavernoma occurred in 8% of patients during follow-up monitoring of medium duration.

Visual function and quality of life among patients with giant cell (temporal) arteritis.

OBJECTIVE: To investigate patient perception of visual and systemic disability associated with giant cell arteritis (GCA) and whether the perceived disability can be correlated with visual performance measures. METHODS: We prospectively evaluated and compared the visual performance and quality of life survey for 20 patients with GCA after 4 to 5 weeks of corticosteroid therapy and after one year of therapy. We measured visual acuity, contrast sensitivity, and threshold perimetry and patients completed the Activities of Daily Vision Scale (ADVS) and the short-form of the Health Survey (SF-36). The results were grouped by GCA affected or unaffected eye or by better or worse eye and reported as a decimal and percent impairment for acuity, log units for contrast, mean deviation and the Advanced Glaucoma Intervention Study (AGIS) score for perimetry. The results for patients with and without visual loss were compared. Correlation analyses between ADVS categories and visual performance measures, SF-36 categories and the presence of visual loss, total corticosteroid dose, systemic symptoms, secondary hypertension or diabetes mellitus, the presence of vertebral fracture, and visual performance were performed. RESULTS: Day driving was the only ADVS category significantly reduced at baseline in patients with visual loss (62.5) compared with those without visual loss (96.3, P = 0.04). Modest to moderate correlations between ADVS categories were most frequent for percent binocular acuity impairment with day driving (r = -0.62, P = 0.017), with distance vision (r = -0.5, P = 0.02), and with glare (r = -0.59, P = 0.006); and the AGIS score of the worse eye with day driving (r = -0.66, P = 0.01), with near vision (r = -0.49, P = 0.03), and with glare (r = -0.48, P = 0.04). The baseline SF-36 scores did not correlate with the presence of vision loss at baseline or systemic complications. The ADVS and SF-36 scores were similar at one year. The total dose of corticosteroids only had a modest correlation with the one-year mental health score (r = -0.45, P = 0.05), but there was no correlation between SF-36 scores and other systemic side effects of steroid therapy. CONCLUSION: Except for the day driving score, the ADVS did not differ between patients with and without visual loss. The SF-36 did not distinguish between patients with and without visual loss and did not reveal significant trends. The ADVS and SF-36 did not reveal significant disability in GCA patients and there were no strong correlations with any visual performance or systemic measures.

Isolated sixth nerve palsy: an uncommon presenting sign of multiple sclerosis.

We describe three patients in whom an isolated sixth nerve palsy was the only clinical symptom or sign of multiple sclerosis (MS). Data were collected prospectively over 6 years on these three patients, who showed no other signs of brainstem dysfunction or prior symptoms; in addition. Retrospective analysis of all patients with MS and all patients with sixth nerve palsy referred to a neuro-ophthalmology service between 1982 and 1998 showed isolated sixth nerve palsy to be the presenting sign of MS in only 0.5% of these patients. MS was the cause of isolated sixth nerve palsy in 0.8% of all patients and in 1.6% of those aged 18-50 years. Although it has been previously suggested that sixth nerve palsy is a not uncommon presenting sign of MS, our results suggest it is rare.

Orbital arteriovenous malformation mimicking cavernous sinus dural arteriovenous malformation.

AIMS: Orbital arteriovenous malformations (OAVM) are rare, mostly described with high flow characteristics. Two cases are reported with an OAVM of distinct haemodynamic abnormality. The clinical, angiographic features, and the management considerations are discussed. METHODS: Case review of two patients with dural AVM (DAVM) who presented to referral neuro-ophthalmology and endovascular services because of clinical symptoms and signs consistent with a cavernous sinus dural AVM. RESULTS: In each patient, superselective angiography revealed a small slow flow intraorbital shunt supplied by the ophthalmic artery. The transarterial and transvenous endovascular approaches to treat the malformation were partially successful. Although, the abnormal flow was reduced, complete closure of the DAVM could not be accomplished without significant risk of iatrogenic injury. Neither patient's vision improved after intervention. CONCLUSION: A DAVM in the orbit can cause similar clinical symptoms and signs to those associated with a cavernous sinus DAVM. Even with high resolution magnetic resonance imaging, only superselective angiography can identify this small intraorbital slow flow shunt. The location in the orbital apex and the small size precludes a surgical option for treatment. The transarterial and transvenous embolisation options are limited.

Visual loss from arterial steal in patients with maxillofacial arteriovenous malformation.

OBJECTIVE: To determine whether an arterial "steal" from the ophthalmic artery accounts for the ocular manifestations associated with maxillofacial arteriovenous malformation (AVM) outside the orbit. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: Seven patients with maxillofacial AVM who had been previously treated, unsuccessfully, with proximal ligation of the supplying external carotid artery branches were evaluated clinically and by superselective cerebral angiography. No cases had intraorbital arteriovenous shunting or abnormal venous drainage to the orbit. INTERVENTION: Endovascular embolization. MAIN OUTCOME MEASURES: Signs and symptoms of ocular ischemia were correlated with findings on cerebral/orbital angiography. RESULTS: Four of seven patients had signs of ocular ischemia. By selective angiography, these four patients were found to have a significant ophthalmic artery supply to the AVM. In contrast, the three patients without signs of ocular ischemia had minimal or no ophthalmic artery supply to the AVM. CONCLUSIONS: When the ophthalmic arterial blood supply is recruited, ophthalmic artery "steal" phenomenon occurs in patients with maxillofacial AVMs that do not directly involve the orbit. This mechanism appears to be the cause of ocular ischemia. It is possible that this "steal" is precipitated or worsened by previous surgical proximal ligation of external carotid arterial branches that are potential collaterals with the ophthalmic artery but fail to occlude the arteriovenous (AV) shunts.

Arachnoid cyst of the cavernous sinus resulting in third nerve palsy.

A 67-year-old man exhibited long-standing left third nerve palsy. Magnetic resonance imaging revealed a cystic lesion in the left cavernous sinus with signal characteristics typical of arachnoid cyst. Intradural cavernous sinus arachnoid cyst has not reported previously. Pathogenetic mechanisms are discussed.

Visual performance in giant cell arteritis (temporal arteritis) after 1 year of therapy.

AIMS: To determine if patients with giant cell arteritis (GCA) treated with corticosteroids develop delayed visual loss or drug related ocular complications. METHODS: In a multicentre prospective study patients with GCA (using precise diagnostic criteria) had ophthalmic evaluations at predetermined intervals up to 1 year. The dose of corticosteroid was determined by treating physicians, often outside the study, with the daily dose reduced to the equivalent of 30-40 mg of prednisone within 5 weeks. Subsequently, treatment guidelines suggested that the dose be reduced as tolerated or the patient was withdrawn from steroids in a period not less than 6 months. RESULTS: At presentation, of the 22 patients enrolled, seven patients had nine eyes with ischaemic injury. Four eyes had improved visual acuity by two lines or more within 1 month of starting corticosteroids. No patients developed late visual loss as the steroid dose was reduced. At 1 year the visual acuity, contrast sensitivity, colour vision, and threshold perimetry were not significantly different from the 4-5 week determinations. At 1 year, there were no significant cataractous or glaucomatous changes. At 2 months, there was no difference in systemic complications between patients who received conventional dose (60-80 mg per day) or very high doses (200-1000 mg per day) of corticosteroids at the start or early in the course. CONCLUSIONS: Patients with GCA related visual loss can improve with treatment. Corticosteroids with starting doses of 60-1000 mg per day, with reduction to daily doses of 40-50 mg per day given for 4-6 weeks, and gradual dose reduction thereafter, as clinically permitted, did not result in delayed visual loss. There were no significant drug related ophthalmic complications.

Visual symptoms with dural arteriovenous malformations draining into occipital veins.

OBJECTIVE: To determine the cause of the visual dysfunction and effect of treatment on dural arteriovenous malformations (DAVMs) that secondarily involve the occipital lobe. BACKGROUND: DAVMs are an infrequent cause of visual dysfunction that should be amenable to treatment if diagnosed before permanent visual field loss. METHODS: The records of seven patients with cerebral visual disturbances associated with DAVMs were analyzed with attention to visual symptoms, visual field testing, and vascular anatomy. RESULTS: Sudden visual loss occurred in five patients, two with a hemorrhage and one with a venous infarct in the occipital lobe. Fortification images occurred in three patients, two of whom had palinopsia (one with de novo formed visual hallucinations). Homonymous quadrantic or hemianoptic field defects, some fluctuating, were found in six patients. Angiography revealed each DAVM was supplied solely by dural arteries and drained into occipital pial veins due to retrograde blood flow through the sites near or in the wall or lumen of the dural venous channels that normally drain the occipital lobe. Unlike DAVMs in other locations, only two patients had occlusion of an adjacent venous sinus. These patients, particularly the two with posterior fossa DAVMs remote to the occipital lobe, clearly demonstrate the visual and neurologic dysfunction resulting from venous hypertension. In six patients, intra-arterial embolization of the arterial feeders and nidus (one patient required additional surgery) resulted in resumption of normal occipital venous emptying. No further visual episodes occurred in five of these six patients. The visual fields normalized in three patients and improved in one with venous infarct but were unchanged in both patients with a hemorrhage. CONCLUSIONS: DAVMs that drain into occipital veins cause field loss and other visual disturbances because of venous hypertension in the occipital lobe, which can be reversed by occluding the DAVM nidus. If a venous infarct or hemorrhage has not caused irreversible damage, visual recovery should be complete.