Background A small proportion of strokes are caused by cerebral arteriovenous malformations (AVM). Treatment to prevent intracranial haemorrhage itself carries risks, and untreated AVM may in many cases have a good prognosis. We investigated the risk of subsequent symptomatic bleeding in the clinical course of AVM in patients with and without an initial haemorrhage.Methods 281 unselected, consecutive, prospectively enrolled patients with cerebral AVM were grouped according to their initial clinical presentation-142 presented with and 139 without haemorrhage. The frequency of AVM haemorrhages during the subsequent clinical course (before the start of endovascular, surgical, or radiation treatment) in the two groups was compared by means of Kaplan-Meier life-tables, log-rank test, and multivariate proportional-hazards regression models, Haemorrhage was defined as a clinically symptomatic event with signs of acute bleeding on computed tomography or magnetic resonance brain imaging,Findings During mean follow-up of 8.5 months for the haemorrhage group and 11.9 months for the nonhaemorrhage group, haemorrhages occurred in 18 (13%) of the former patients and in three (2%) of the latter (p=0.0002). The annual risk of haemorrhage was 17.8% and 2.2%, respectively. In the multivariate regression model, the adjusted hazard ratio for haemorrhage at initial presentation was 139 (95% CI 2.6-73.8; p=0.002). Deep venous drainage (hazard ratio 4.1 [1.2-14.9], p=0.029) and male sex (9.2 [2.1-41.3], p=0.004) were also significantly associated with subsequent haemorrhage, but no significant association was found for age or AVM size. The annual rate of spontaneous haemorrhage was 32.6% for men and 10.4% for women in the haemorrhage group compared with 3.3% for men and 1.3% for women in the non-haemorrhage group. Among patients with haemorrhage at initial presentation, the risk of haemorrhage fell from 32.9% in year 1 to 11.3% in subsequent years (34.2% to 31.0% in men; 31.1% to 5.5% in women).Interpretation In AVM, patients initially presenting with haemorrhage have a higher risk of subsequent bleeding than those presenting with other symptoms. The risk is higher in men than in women.

We studied seven patients with left cerebral atriovenous malformation (AVM) with superselective arterial injection of anesthetics during angiography to determine whether there was translocation of some language functions to other regions in the ispilateral hemisphere. All patients were right handed. With a catheter inserted into each target vessel, patients underwent aphasia examination in an A-B-A design: (A) baseline, no anesthetic; (B) 1 minute after anesthetic injection; and (A) 12 minutes after injection (when its effects had dissipated). The results showed that six of seven patients had no significant aphasia at baseline or 12 minutes after anesthetic injection. One patient had a mild conduction aphasia at baseline and after anesthetic effects had dissipated. In the six patients with temporoparietal AVM, anesthetic injections into vessels in the lower division of the middle cerebral artery (MCA) not feeding the AVM (e.g., the left angular artery) produced a wide range of language function--from conduction aphasia to dense Wernicke's syndromes. When upper division MCA vessels were injected (e.g., the prefrontal branch), all developed a major aphasic disorder with significant comprehension defects. A seventh patient with a frontal opercular AVM had a mild anomia, semantic paraphasias, and decreased word-list generation when the prefrontal branch was injected. Her comprehension, however, was intact. These data show that patients with posterior cerebral AVM can show language abnormalities where such deficits are not typically seen after acute brain injury. These findings support a posterior-to-anterior extension of some language skills under conditions of brain disease.

BACKGROUND Several surgical approaches have proven effective in the management of colloid cysts. Cited disadvantages of the transventricular route are its difficulty in patients with small ventricles, and the risk of postoperative seizures; advantages include the avoidance of interhemispheric retraction and venous injury, and callosal section in the transcallosal route.METHODS We retrospectively evaluated patient outcomes after minimally invasive transventricular microsurgical resection, Twenty patients underwent computed tomography-guided stereotactic resection of a colloid cyst based on trajectory planning through the middle frontal gyrus. The mean patient age was 38 years (range, 14-65 years). The colloid cyst was discovered incidentally in one patient; two patients presented in coma. Fourteen patients (70%) had preoperative hydrocephalus.RESULTS Total or near-total (only a small remnant of cyst wall left attached to the fornix or thalamostriate vein) cyst removal was achieved in all patients. Mean follow-up after surgery was 4.3 years (range, 0.5-11 years). All patients had an excellent outcome (100%) with return to full function or employment status. Postoperative morbidity occurred in one patient (5%) who sustained a small caudate nucleus hemorrhagic contusion associated with temporary hemiparesis. A single postoperative seizure occurred in one patient 5 months after surgery; no patient developed a persistent seizure disorder.CONCLUSIONS This technique relies on the use of a precisely placed limited craniotomy, a small cortical opening (10-20 mm), a precise trajectory to the foramen of Monro, and standard microsurgical instruments. Stereotactic transventricular microsurgical resection provided safe and effective management of patients with colloid cysts, even in the absence of hydrocephalus. (C) 1996 by Elsevier Science Inc.

BACKGROUND Temporal lobe arteriovenous malformations (AVMs) represent a subgroup of intracranial AVMs with particular characteristics and management issues. METHODS We performed a retrospective analysis of 24 consecutive patients with temporal lobe AVMs treated with surgical excision. Factors such as location, size, arterial feeders, venous drainage, and clinical follow-up were recorded for each. Results were compared with those of 132 patients with nontemporal lobe AVMs surgically treated over the same time period. RESULTS Sixteen of the temporal AVMs were located in the convexity, six in the mesotemporal region, and two were predominantly intraventricular. The mode of presentation was seizure in 11 patients, hemorrhage in 7, headache in 4, and 2 were asymptomatic. Patients with convexity AVMs more commonly presented with seizures, whereas patients with mesotemporal or intraventricular AVMs were more likely to present with hemorrhage. One patient with subarachnoid hemorrhage from a basilar artery aneurysm died. Postoperatively, 2 patients (8.3%) had a new hemiparesis and dysphasia, 1 (4%) had a new dysphasia and hemianopsia, and 3 others (13%) were left with an isolated superior quadrant field deficit. Lasting surgical morbidity other than isolated field deficit was 13% for patients with temporal AVMs and 15% for those with nontemporal AVMs. CONCLUSIONS Temporal lobe AVMs may be successfully resected using a direct microsurgical approach with limited morbidity and excellent prognosis for recovery. Most of the deficits relating to AVM hemorrhage and those of the immediate postoperative period improved significantly over the subsequent few months.

PURPOSE To determine the influence of preoperative N-butyl cyanoacrylate embolization on outcome in the treatment of cerebral arteriovenous malformations. METHODS Two groups were compared: 30 patients who underwent surgery and embolization versus 41 patients who underwent surgery only. Both groups were categorized by Spetzler-Martin grade and evaluated with the Glasgow Outcome Scale at various intervals. The long-term follow-up in months was, for surgery only, mean of 35 and range of 4 to 59, and for surgery and embolization, mean of 10 and range of 1 to 19). RESULTS The arteriovenous malformations in the surgery and embolization group had a larger average greatest diameter (4.2 +/- 1.5 cm versus 3.4 +/- 1.8 cm) and were of higher Spetzler-Martin grade (89% versus 68% grade III-V). No significant difference in the preoperative or immediate postoperative (less than 24 hours) Glasgow Outcome Scale was identified between the two groups. At I week after surgery, the surgery and embolization group displayed a significantly better outcome evaluation (70% versus 41% with Glasgow Outcome Scale score of 5). The long-term evaluation continued to favor the surgery and embolization patients (86% versus 66% with Glasgow Outcome Scale score of 5). CONCLUSION Preoperative N-butyl cyanoacrylate embolization improves postsurgical outcome.

Intradural spinal lipomas that are not associated with spinal dysraphism are rare. We report four cases of adult patients with intradural spinal lipomas. All of the patients were young adults, three women and one man, who ranged in age from 22 to 37 years (mean, 30.3 yr). The clinical presentation of these lesions varied, depending upon the size and location of each lipoma. It is interesting that the symptoms in the women gradually deteriorated during pregnancy or after delivery. Magnetic resonance imaging was very useful in determining the exact location of lipoma. In three of four patients, neurological improvement was obtained after decompressive laminectomy and partial removal of the lipoma.

PURPOSE: To characterize cerebral hemodynamics in patients immediately before microsurgical resection of moderate to large arteriovenous malformations during isoflurane anesthesia. METHODS: In angiographically defined arteriovenous malformation feeding and nonfeeding arteries, transcranial Doppler studies were performed in 25 surgeries on 22 patients. The mean blood flow velocity and pulsatility index were recorded in the middle, anterior, and posterior cerebral arteries. Transcranial Doppler velocities were measured at end-tidal carbon dioxide tensions (PetCO(2)) of about 25 and 35 mm Hg. Carbon dioxide reactivity was calculated as percentage mean blood flow velocity change per mm Hg PetCO(2) change. RESULTS: Patient demographic and clinical data for the arteriovenous malformation group followed the expected strata of a large arteriovenous malformation population. All patients were neurologically stable before surgery. A total of 43 feeding arteries and 55 nonfeeding arteries were studied. Compared with nonfeeders, feeders exhibited higher mean blood flow velocity (68 +/- 5 vs 31 +/- 3 cm/sec, P < 0.0001) and lower pulsatility index (0.64 +/- 0.03 vs 0.88 +/- 0.04, P < 0.001); anterior and middle cerebral artery velocities at normo- and hypocapnia were significantly higher than posterior cerebral arteries for both feeders and nonfeeders (P < 0.001). Carbon dioxide reactivity was 0.2 +/- 0.2 %/mm Hg in feeders and 2.1 +/- 0.2 %/mm Hg in nonfeeders, with no significant difference between arteries. In four of eight patients with lesions fed by the anterior circulation (middle cerebral artery with or without anterior cerebral artery feeders), posterior cerebral artery nonfeeders exhibited low reactivity. In 2 of 5 patients with ipsilateral posterior cerebral artery feeders, contralateral posterior cerebral artery nonfeeders exhibited impaired reactivity. CONCLUSIONS: Quantitative transcranial Doppler studies are technically feasible in the operating room or interventional suite during anesthesia. Hemodynamic assessment using physiologic challenges of arteriovenous malformation feeders as well as angiographically uninvolved Vessels may be useful as criteria in the assessment of malformations and arteriovenous malformation patients may exhibit abnormal vasoreactivity in distant uninvolved perfusion territories, suggesting a deranged neural control mechanism.

THE RESULTS IN the surgical management of 26 patients with arteriovenous malformations intimately related to the trigone of the lateral ventricle are presented. Three operative approaches were used in the series, including a transtemporal route through the inferior or middle temporal gyrus (15 patients), an interhemispheric approach (8 patients), and a transcortical parieto-occipital approach (3 patients). The surgical approach was chosen on the basis of the relationship of the arteriovenous malformation to the trigone, the presence and location of associated hematoma, and preoperative neurological deficits. This report emphasizes the use of surgical adjuncts that are instrumental in the management of these challenging lesions, including magnetic resonance imaging for precise localization and operative planning, preoperative embolization to obliterate deep arterial supply, and intraoperative ultrasound and angiography to aid in localization and to document complete excision of the arteriovenous malformation before closure. The results of the management of these 26 patients are as follows: 21 had no or minor neurological deficits and were able to resume premorbid activities; 2 had a fair result, being independent but unable to resume their premorbid occupation; 2 had a poor result and were dependent as the result of an incapacitating neurological deficit; and 1 died.

Background and Purpose: Feeding mean arterial pressure immediately proximal to the nidus of arteriovenous malformations may influence the frequency of spontaneous intracerebral hemorrhage. This study assessed the usefulness of transcranial Doppler ultrasound velocities as a noninvasive estimate of feeding mean arterial pressure.Methods: We studied 41 patients undergoing 73 staged treatments of arteriovenous malformations with endovascular embolization, surgery, or both. Before treatment during the awake state, transcranial Doppler mean and peak velocities were recorded in proximal Willisian vessels. During superselective angiography with the patient under conscious sedation or during surgery with the patient under general anesthesia, feeding mean arterial pressure was measured through a 1.5F transfemoral intracranial microcatheter or a 26-g needle by direct puncture. Measurement of insonated artery diameter was possible in 41 embolizations, and a flow velocity index (mL/min) and Reynolds' number were estimated.Results: Mean+/-SEM feeding mean arterial pressure was 38+/-2 mm Hg at a systemic mean arterial pressure of 77+/-2 mm Hg; mean velocity was 102+/-4 cm/s. There was an inverse correlation between feeding mean arterial pressure and parent artery mean velocity (y=-0.74x+130, r=.35. P=.0025). The best correlation was for the first treatment in each patient (n=27) using the highest peak velocity obtainable in a Willisian vessel ipsilateral to the arteriovenous malformation (y=-1.61x+221, r=.62, P=.0005). Flow velocity index (775+/-106 mL/min) did not correlate with feeding mean arterial pressure, but there was a weak correlation with Reynolds' number (y=-12x+1616, r=.27, P=.1283). Mean Reynolds' number was 1257+/-119.Conclusions: Transcranial Doppler mean velocity is correlated with feeding mean arterial pressure but only weakly predictive. Considerations influencing the relation of distal feeding mean arterial pressure to proximal mean velocity might include the influence of other fistulae in the circuit between major inflow and outflow channels as well as turbulent flow at vascular branch points between point of insonation and the nidus, as suggested by Reynolds' number values of more than 400.

Young, W L MD; Pile-Spellman, J MD; Prohovnik, I PhD; terPenning, B MD; Stein, B M MD the Columbia AVM Project Author Information

Kader, A MD; Young, W L MD; Baker, K Z MD; Fleischer, L H MD; Sisti, M B MD; Pile-Spellman, J MD; Stein, B M MD Author Information

THE MICROSURGICAL EXCISION of arteriovenous malformations located in the thalamic region in eight patients is reported. Six were located in the posterior aspect of the thalamus and two were located in the anterior. Hemorrhage occurred in all of the cases. Hemiparesis, hemianesthesia, and consciousness disturbance were the most typical clinical features. The supine position with the anterior transcallosal approach was used for anterior dorsal lesions, and the sitting position with the posterior interhemispheric approach was used for posterior dorsal lesions. Total removal was confirmed by angiography in seven patients, and incomplete removal was noted in one patient. There was one death in this group of patients. Memory disturbance was the most common postoperative complication. This complication showed considerable improvement with time. Other complications included homonymous hemianopsia (three patients), hemisensory loss (six patients), and transient hemiparesis (one patient). All survivors (seven patients) were able to return to their occupation after surgery. The vascular input, the location of the malformation, and clinical history are the contributory factors concerning operability. With the modern neurosurgical and anesthesiological facilities, surgical removal of thalamic malformations in selected cases is advisable.

THE LOSS OF autoregulatory control of cerebral perfusion to changes in perfusion pressure in tissue remote from an arteriovenous malformation (AVM) has been proposed as the mechanism underlying ''normal perfusion pressure breakthrough.'' This study is the first direct test of this mechanism. Studies were performed during the resection of moderate to large AVMs in 25 patients undergoing 28 procedures under isoflurane anesthesia. Cerebral blood flow (CBF) was measured (xenon-133 method) in the hemisphere adjacent to the nidus before resection after dural exposure (pre), after AVM removal before dural closure at spontaneous systemic blood pressure (post), and, finally, with the mean arterial pressure increased by 20 mm Hg, using phenylephrine (post-BP). AVM resection resulted in a significant enhancement of perfusion in the adjacent hemisphere (30 +/- 2 vs. 25 +/- 1 ml/100g/min, P < 0.01), but no further increase of CBF occurred during increased perfusion pressure (30 +/- 2 ml/100g/min). One patient suffered a postoperative hemorrhage and another developed intraoperative brain swelling during the course of the resection that necessitated staging the procedure. These two patients had the highest increases in CBF, but intact pressure autoregulation. Preserved autoregulation to increased mean arterial pressure after resection does not support a hemodynamic mechanism for the observed increase in CBF from before the resection to after the resection. Pathological events, however, do appear to be related to increases in hemispheric perfusion.

The removal of large arteriovenous malformations (AVMs) in stages has been advocated to reduce the risk of perioperative hyperemic complications. In three patients who had a two-stage surgical removal of their large (> 6 cm) frontal AVMs, transcranial Doppler (TCD) was performed 1 day before and 1 day after each surgery. Arteries still feeding the AVM after the first procedure had an increase in mean velocity (MV) and a decrease in the pulsatility index (PI) in the period between the two surgeries. MV reactivity to carbon dioxide before each stage was higher in feeding arteries at the second surgery, suggesting that the total magnitude of the shunt through the AVM was lower in spite of flow recruitment. TCD can be used to monitor the hemodynamic changes after embolization or partial surgery and may be of help in better defining the optimal time for final resection.