Removal of Occipital Arteriovenous Malformations With Sparing of Visual Fields Jorge C. Kattah, MD; Alfred J. Luessenhop, MD; Martin Kolsky, MD; Francisco Ferraz, MD \s=b\ Two patients with occipital lobe arteriovenous malformation (AVM) underwent two-stage resection of their lesions. The intervals between operations were eight and 12 days. Prior to surgery, the patients had normal neuro-ophthalmologic examination results and both experienced a reversible homonymous hemianopsia after the initial, partial resection of the AVM. Frequent seizures with visual hallucinations developed in the early postoperative period, with gradual improvement of the visual field defect. The pattern and duration of visual disturbances and the nature of the visual field defects in each patient had similar characteristics. The second operation with complete resection of the AVMs left normal visual fields. (Arch Neurol 1981;38:307-309) Ourgical removal of an arteriovenous malformation (AVM), as recently summarized by Stein and Wolpert,' is the ideal method of treatment when possible. We describe two patients who underwent resections of occipital lobe AVMs. The operations were per¬ formed in two stages, with intervals of eight and 12 days. After the first operation, both patients experienced a reversible homonymous hemianopsia Accepted for publication Sept 10, 1980. From the Departments of Neurology (Drs Kattah and Kolsky) and Neurosurgery (Drs Luessenhop and Ferraz), Georgetown University School of Medicine, Washington, DC. Reprint requests to Department of Neurology, Georgetown University School of Medicine, 3800 Reservoir Rd NW, Washington, DC 20007 (Dr Kattah). associated with visual hallucinations. These symptoms resolved rapidly with anticonvulsant therapy, and a second operation with complete resection of the AVM left normal visual fields. REPORT OF CASES l.-A 26-year-old, right-handed referred for evaluation of an AVM in the right occipital lobe. He had been well until three weeks before admis¬ sion, when he had two major motor sei¬ zures. Seizures were preceded in both instances by brief, blinking, red and blue colored lights in the left peripheral visual field and were followed by two hours of postictal amnesia. The patient was transferred to George¬ Case man town was University Hospital, Washington, DC, after angiography demonstrated an AVM of the right occipital lobe. There were normal vision, normally reactive equal pupils, normal ocular movements, and intact visual fields plotted with the Goldmann perimeter. No ocular or cranial bruits were detected. The main arterial supply to the AVM originated from the right posterior tempo¬ ral and angular arteries and to a lesser extent from the right calcarme artery. The site of artery-to-vein communication was located lateral to the occipital pole, and the venous drainage was adjacent to the sagit¬ tal sinus (Fig 1). The patient agreed to undergo resection of the AVM to prevent the possibility of further complications and to avoid restrictions in his future physical activity, even though he was forewarned of the possibility of a permanent visual field defect. Surgery was done in two stages. In the initial procedure, coagulation and clipping of the major feeding arteries and smaller branches using the operating microscope completed without complications. Eight hours after operation, visual fields tested by confrontation revealed a left homonymous hemianopsia. The next morn¬ ing, the patient had intermittent visual hallucinations characterized by compli¬ cated patterns of silvery, bright, hexagonal geometric figures that moved from the center to the periphery of the left visual field; although the visual disturbances were isolated and lasted only seconds, on two occasions they were associated with major motor seizures. Adjustment of the anticonvulsant drug dosage led to cessation was of symptoms. The EEG demonstrated slow 2.5- to 4.0-Hz rhythm originating in the right posterior temporal and occipital leads with continuous polyspike discharges. For¬ ty-eight hours after surgery, the patient began to perceive hand motion in the defective field, and ten days later his visual fields were normal. A second cerebral angiogram showed abnormal residual vasculature (Fig 2), but there was obliteration of the major arterial channels that formerly supplied the lesion. A second operation was performed 12 days after the first. After clipping of the resid¬ ual arterial supply and coagulation of smaller vessels, the vascular mass was totally obliterated. The postoperative peri¬ od was normal and unassociated with visual symptoms. The visual field plotted with the Goldmann perimeter remained normal, and a third cerebral angiogram confirmed total resection of the lesion (Fig 3). Neuro-ophthalmologic examination re¬ sults during the ensuing six months have been normal. The patient remains free of seizures. Case 2.-A 38-year-old woman was referred for evaluation of a right occipital lobe AVM. She complained of recurrent right-sided headaches since her first preg¬ nancy, when she was a teenager. Often, the Downloaded From: http://archneur.jamanetwork.com/ by a University of California - San Diego User on 06/03/2015 Fig 1.—Left, anteroposterior and lateral views of midarterial phase of right carotid angiogram in patient 1. Arteriovenous malformation in occipital lobe is observed, main arterial supply originates from posterior temporal and angular arteries, and venous drainage is adjacent to sagittal and transverse sinuses. Right, Anteroposterior and lateral views of midarterial phase of right vertebral angiogram in patient 1 demonstrates additional arterial supply from right calcarine artery. Fig 2.—Lateral view of early venous phase of right carotid angiogram in patient 1. Arteriovenous malformation decreased in size, and small residual feeders are identi¬ fied after first operation. Fig 3.—Lateral views of midarterial phases of right vertebral (left) and right carotid (right) angiograms demonstrating complete obliteration of arteriovenous malformation accom¬ plished at second procedure in patient 1. Fig 4.—Left, Lateral and anteroposterior views of right carotid angiogram (midarterial phase) in patient 2. Abnormal arterial vessels originating from angular and other branches of middle cerebral artery supply large occipital lobe arteriovenous malformation. Observe early venous drainage to superior sagittal sinus. Right, Lateral and anteroposterior views of left vertebral artery injection in same patient. Additional arterial supply originating from branches of calcarine artery are demonstrated. Downloaded From: http://archneur.jamanetwork.com/ by a University of California - San Diego User on 06/03/2015 headaches were preceded by scintillating, silvery scotoma that moved from the cen¬ ter to the periphery of the left visual field and lasted an average of 30 minutes. The scotomata slowly faded into a dense fog that occupied the entire left field. Nausea and vomiting were frequently associated symptoms. The headache had become more intense and did not respond to therapy with propranolol hydrochloride, ergot de¬ rivatives, and analgesics. Eight weeks prior to admission, she had disabling head¬ aches daily. Examination showed normal vision, nor¬ mally reactive, equal pupils, and intact visual fields plotted with the Goldmann perimeter. Oculomotor examination results were normal and no cranial or ocular bruits were audible. Angiography demonstrated a large AVM, measuring 4x5 cm, in the right occipital lobe. The calcarine and other small branches of the right posterior cerebral artery were the main arterial supply, with additional supply from the angular, poste¬ rior parietal, and posterior temporal branches of the middle cerebral artery. The venous drainage was to right lateral and superior sagittal sinuses (Fig 4). Because of the severity of the headaches and the failure to respond to medical therapy, the patient agreed to undergo resection of the AVM. Surgery was done in two stages. In the first procedure, clipping of accessible arterial feeders was achieved without com¬ plications. Twelve hours later, visual fields tested by confrontation demonstrated the presence of a dense left homonymous hemianopsia, two days later there was perception of hand motion in the defective field, and within four days after operation, the visual fields plotted with the Goldmann perimeter were normal. While recovering during the first postoperative week, the patient described visual distortions in the left field. Even though she was able to recognize familiar objects, they seemed to be surrounded by a shadow of smoke that shifted continuously; to avoid these distur- bances, she kept her eyes closed most of the time. In addition, the patient experienced intermittent, visual hallucinations charac¬ terized by brief, unformed, elementary flashing lights in the left field; phenytoin sodium was administered, with reduction of the scotomata. One week later, an angio¬ gram demonstrated obliteration of the major vessels that formerly supplied the AVM. Complete resection of the vascular mass was accomplished eight days after the initial procedure. During this postoper¬ ative course, the patient also described persistent visual hallucinations in the left field, which gradually improved. One week after the second operation, Goldmann visual fields and EEG were normal. The patient has remained free of headaches and seizures for nine months. Anticonvul¬ sant therapy has now been discontinued and current examination results are normal. COMMENT A common denominator in cases of transient homonymous visual field defects may be prolonged ischemia without permanent neuronal damage in the occipital lobes. The reversibility of the dense homonymous hemianop¬ sia seen in our two patients suggests that the partial resections of the lesions at the first operation could have been associated with transient ischemia that did not lead to infarc¬ tion. Spreading depression of the cor¬ tical activity following surgical ma¬ nipulation of the occipital lobe could also have been a contributing factor in the development of reversible postop¬ erative homonymous hemianopsia and visual hallucinations in our cases.- ' Postictal homonymous hemianopsia4 is another consideration in these two patients with known occipital lobe sei¬ zure foci. Our present policy for resection of larger, critically located cerebral AVMs is to perform the surgery in two or more stages. In the first stage, the critical arteries supplying the lesion are interrupted, and a plane of cleavage along the margins between the abnormal vascular channels and normal brain is established. The pro¬ cedure is terminated before notable edema appears in the adjacent brain tissue. Resection is completed in the second stage after the edema has sub¬ sided and normal autoregulation pre¬ sumably is restored. Manipulation of edematous brain is thereby avoided and the possibility of neurologic defi¬ cit is minimized. Paroxysmal visual disturbances, probably originating from epileptogenic foci, were de¬ scribed by these two patients shortly after surgery. In addition, patient 2 had constant visual distortions charac¬ terized by motion of indistinct objects in the left visual field, which likely represent release phenomena.' " All symptoms responded promptly to an¬ ticonvulsant medication. References 1. Stein BM, Wolpert SM: Arteriovenous malformations of the brain: II. Current concepts and treatment. Arch Neurol 1980;37:69-75. 2. Leao AA: Spreading depression of activity in the cerebral cortex. J Neurophysiol 1944;7:391\x=req-\ 396. 3. Leao AA: Further observations on the spreading depression of activity in the cerebral cortex. J Neurophysiol 1947;7:391-396. 4. Salmon LH: Post ictal hemianopsia. Arch Ophthalmol 1968;79:523-525. 5. Cogan DG: Visual hallucinations as release phenomena. Albrecht Von Graefes Arch Klin Exp Ophthalmol 1973;188:139-150. 6. Brust JCM, Behrens MM: 'Release hallucinations' as the major symptom of posterior cerebral artery occlusion: A report of two cases. Ann Neurol 1977;2:432-436. Downloaded From: http://archneur.jamanetwork.com/ by a University of California - San Diego User on 06/03/2015