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B M Stein

Publications and source records attributed to B M Stein.

At least 19 recordsLinked to original sources
PubMed1996

Intramedullary spinal cord metastasis: report of three cases and review of the literature.

BACKGROUND: Intramedullary spinal cord metastasis is rare; but it is being encountered with increasing frequency. Optimal treatment after diagnosis remains controversial. METHODS: In the last 3 years, we have encountered three cases of intramedullary metastasis presenting as focal mass lesions with minimal systemic evidence of cancer. We present our results in these patients and review the literature in an effort to more optimally define both the natural course of this disease, as well as a potential subset of patients who might benefit from more aggressive treatment. RESULTS: With the availability of more sensitive imaging techniques, these tumors are being diagnosed with increasing frequency. Magnetic resonance imaging is sensitive, but nonspecific, in distinguishing intramedullary spinal cord metastases from primary cord tumors. Urgent biopsy is often necessary prior to definitive treatment. Radiation with chemotherapy significantly prolongs survival. Radical subtotal resection may offer additional quality survival, especially in cases of metastatic melanoma with an occult primary. CONCLUSIONS: Regardless of treatment, many patients survive less than 1 year. Intramedullary spinal cord metastasis is a devastating condition, but with appropriate diagnosis and aggressive treatment, selected patients may have substantially increased survival.

Breast Neoplasms↗
PubMed1996

Cerebral hyperemia after arteriovenous malformation resection is related to "breakthrough" complications but not to feeding artery pressure. The Columbia University Arteriovenous Malformation Study Project.

To study the pathophysiology of idiopathic postoperative brain swelling or hemorrhage after arteriovenous malformation resection, termed normal perfusion pressure breakthrough (NPPB), we performed cerebral blood flow (CBF) studies during 152 operations in 143 patients, using the xenon-133 intravenous injection method. In the first part of the study, CBF was intraoperatively measured (isoflurane/N2O anesthesia) during relative hypocapnia in 95 patients before and after resection. The NPPB group had a greater increase (P < 0.0001) in mean +/- standard deviation global CBF (28 +/- 6 to 47 +/- 16 ml/100 g/min, n = 5) than did the non-NPPB group (25 +/- 7 to 29 +/- 10 ml/100 g/min, n = 90); both arteriovenous malformation groups showed greater increase (P < 0.05) than did controls undergoing craniotomy for tumor (23 +/- 6 to 23 +/- 6 ml/100 g/min, n = 22). Ipsilateral and contralateral CBF changes were similar. In a second cohort of patients with arteriovenous malformations, CBF was measured at relative normocapnia and it increased (P < 0.002) from pre- to postresection (40 +/- 13 to 49 +/- 15 ml/100 g/min, n = 57). There were no NPPB patients in this latter cohort. The feeding mean arterial pressure was measured intraoperatively before resection or at the last embolization before surgery (n = 64). The feeding mean arterial pressure (44 +/- 16 mm Hg) was 56% of the systemic arterial pressure (78 +/- 12 mm Hg, P < 0.0001) and was not related to changes in CBF from pre- to postresection. There was an association between increases in global CBF from pre- to postresection and NPPB-type complications, but there was no relationship of these CBF changes to preoperative regional arterial hypotension. These data do not support a uniquely hemodynamic mechanism that explains cerebral hyperemia as a consequence of repressurization in hypotensive vascular beds.

Adult↗
PubMed1996

Intraoperative monitoring of motor evoked potentials: a review of 116 cases.

We reviewed the results of motor evoked potential (MEP) and somatosensory evoked potential (SEP) monitoring during 116 operations on the spine or spinal cord. We monitored MEPs by electrically stimulating the spinal cord and recording compound muscle action potentials from lower extremity muscles and monitored SEPs by stimulating posterior tibial or peroneal nerves and recording both cortical and subcortical evoked potentials. We maintained anesthesia with an N2O/O2/opioid technique supplemented with a halogenated inhalational agent and maintained partial neuromuscular blockade using a vecuronium infusion. Both MEPs and SEPs could be recorded in 99 cases (85%). Neither MEPs nor SEPs were recorded in eight patients, all of whom had preexisting severe myelopathies. Only SEPs could be recorded in two patients, and only MEPs were obtained in seven cases. Deterioration of evoked potentials occurred during nine operations (8%). In eight cases, both SEPs and MEPs deteriorated; in one case, only MEPs deteriorated. In four cases, the changes in the monitored signals led to major alterations in the surgery. We believe that optimal monitoring during spinal surgery requires recording both SEPs and MEPs. This provides independent verification of spinal cord integrity using two parallel but independent systems, and also allows detection of the occasional insults that selectively affect either motor or sensory systems.

Evoked Potentials, Motor↗
PubMed1996

Recurrent cerebral arteriovenous malformations after negative postoperative angiograms.

Angiography has been considered to be the gold standard to judge the success of treatment for cerebral arteriovenous malformations (AVMs). Patients without residual nidus or early draining veins on postoperative angiograms are considered cured, with the risk of hemorrhage eliminated. A series of five patients with recurrent AVMs after negative postoperative angiography is described. All patients had hemispheric AVMs, presented initially with hemorrhage, and were between 5 and 13 years of age. Recurrence was noted 1 to 9 years later (at 12-16 years of age); after a hemorrhage in three patients, seizures in one, and on follow-up magnetic resonance imaging in one. Four patients underwent angiography that showed recurrence of the AVM at or adjacent to the original site. Three years postsurgery, the fifth patient died from a large intracerebral and intraventricular hemorrhage originating in the previous location of the AVM; however, the patient did not undergo angiography at the time of recurrence. The initial negative angiograms obtained postoperatively in these patients may be explained by postoperative spasm or thrombosis of a small residual malformation. However, in the authors' cumulative experience with 808 patients who have undergone complete surgical removal of AVMs (of whom 667 were older than 18 years of age), no case of recurrent AVM has been observed in an adult. Therefore, actual regrowth of an AVM may occur in children and could be a consequence of their relatively immature cerebral vasculature and may involve active angiogenesis mediated by humoral factors. The present findings argue against the assumption that AVMs are strictly congenital lesions resulting from failure of capillary formation during early embryogenesis. It is concluded that delayed imaging studies should be considered in children at least 1 year after their initial negative postoperative arteriogram to exclude a recurrent AVM.

Adolescent↗
PubMed1995

Surgical management of pineal region tumors.

The authors advocate an aggressive surgical approach to pineal region tumors to provide a definitive histological diagnosis and to facilitate extensive tumor removal. This strategy is based on their surgical experience in 160 operations for pineal region tumors in which operative mortality was 4% with 3% permanent major morbidity. One-third of pineal tumors were benign for which surgery alone was usually curative. A gross total removal was possible in 31 of 107 malignant tumors. The supracerebellar infratentorial approach was preferred in 86% of patients. The tumors displayed considerable histological diversity with germ cell tumors most common (37%), followed by glial cell tumors (28%) and pineal cell tumors (23%). Mixed tumors occurred 15% of the time. Spinal metastases were rare, occurring in less than 10% of patients with malignant tumors. These results with a large series of pineal region tumors demonstrate the safety and efficacy of aggressive pineal tumor surgery.

Adolescent↗
PubMed1995

'Steal' is an unestablished mechanism for the clinical presentation of cerebral arteriovenous malformations.

BACKGROUND AND PURPOSE: Focal neurological deficits (FNDs) in patients with arteriovenous malformations (AVMs) have been widely attributed to the phenomenon of "cerebral steal." The incidence of focal deficits was investigated in a large prospective sample. METHODS: Using data from patient history and examination, CT or MRI, and transcranial Doppler sonography, we studied 152 consecutive, prospective AVM patients for evidence of FNDs unrelated to a hemorrhagic event. Feeding mean arterial pressure was measured during superselective angiography. RESULTS: Two (1.3%) of 152 patients met the criteria for a progressive FND. Nonprogressive FNDs were seen in 11 (7.2%) patients (stable in 4.6%, reversible in 2.6%). The median observation time period was 17 months (range, 1 to 60 months). There were no differences in transcranial Doppler mean velocities in feeding arteries in FND versus non-FND groups (118 +/- 44 versus 112 +/- 37 cm/s, P > .05) or pulsatility indexes (0.53 +/- 0.20 versus 0.55 +/- 0.15, P > .05). Feeding artery pressure was similar in FND (n = 10) and non-FND (n = 96) groups (39 +/- 16 versus 39 +/- 16 mm Hg at a systemic pressure of 82 +/- 18 versus 75 +/- 14 mm Hg, NS). CONCLUSIONS: Nonhemorrhagic focal neurological syndromes in AVM patients are infrequent. Progressive deficits are especially rare. There was no relation between feeding artery pressure or flow velocities and FND. There does not appear to be sufficient evidence to assign steal as an operative pathophysiological mechanism in the vast majority of AVM patients.

Adult↗
PubMed1995

Outcome analysis of preoperative embolization with N-butyl cyanoacrylate in cerebral arteriovenous malformations.

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.

Adult↗
PubMed1994

Evidence for adaptive autoregulatory displacement in hypotensive cortical territories adjacent to arteriovenous malformations. Columbia University AVM Study Project.

We hypothesized that chronic hypotension in normal vascular territories fed by arteriovenous malformation pedicles may reset the lower limit of autoregulation and allow flow to remain constant over a lower pressure range. We studied the effect of increasing systemic mean arterial pressure (SMAP) with phenylephrine on cerebral blood flow using a novel technique. Fourteen patients undergoing 15 procedures were studied before endovascular embolization of arteriovenous malformations under neuroleptic conscious sedation. Mean pressures were transduced via a 1.5-F intracranial microcatheter, which was passed under fluoroscopic guidance into the target feeding artery. The microcatheter was positioned (unwedged) at a point that was relatively hypotensive to systemic pressure but that irrigated normal cortex on angiography; feeding mean arterial pressure (FMAP) and SMAP were recorded. A bolus of 133Xe in saline was injected into the microcatheter, and washout was recorded for 3 minutes by a scintillation detector placed over the vascular territory of the injected pedicle. SMAP was then increased approximately 25 mm Hg by phenylephrine infusion, a second bolus was given, and washout was recorded. After exclusion of the shunt spike, initial slope was calculated. The SMAP (mean +/- standard error) increased from 65 +/- 3 to 89 +/- 2 mm Hg (P < 0.0001), and FMAP increased from 46 +/- 3 to 63 +/- 3 mm Hg (P < 0.0001); cerebral blood flow did not change (40 +/- 2 to 40 +/- 2 ml/100 g per min, P = 0.9199). Dividing the cases on the basis of the baseline FMAP into a "severe" hypotensive group (FMAP = 38 +/- 2; n = 7) and a "moderate" hypotensive group (FMAP = 54 +/- 3; n = 8), cerebral blood flow did not change in either group during phenylephrine challenge. Chronic hypotension does not necessarily result in "vasomotor paralysis" with loss of the ability to vasoconstrict to acute increases in perfusion pressure. Instead, it appears to displace adaptively the lower limit of autoregulation in affected vascular territories by a shift of the autoregulatory curve to the left, conceptually analogous to the adaptive displacement seen with chronic hypertension and its treatment.

Adolescent↗
PubMed1994

The influence of hemodynamic and anatomic factors on hemorrhage from cerebral arteriovenous malformations.

The physiological and anatomical aberrations that result in hemorrhage from cerebral arteriovenous malformations (AVMs) remain unclear. In an attempt to clarify which conditions may predispose to hemorrhage, we examined clinical and physiological indices on presentation groups of either hemorrhage or nonhemorrhage in a large cohort of patients (n = 449). Variables examined included AVM size, type of venous drainage, transcranial Doppler (TCD) velocities, feeding mean arterial pressure (FMAP), and draining vein pressure. TCD and pressure data were obtained before any treatment. Age (mean +/- standard deviation) at the time of presentation was 33 +/- 13 years and did not differ between groups. Patients with small (< or = 2.5 cm) AVMs presented more frequently with hemorrhage (90%) than did patients with medium (> 2.5 and < or = 5.0 cm; 52%) or large (> 5.0 cm; 50%) AVMs (P = 0.0001). The 48 of 94 AVMs (51%) with deep venous drainage were more likely to have hemorrhage (P = 0.0219) than were those with superficial drainage (24 of 73 [33%]). Deep drainage was a predictor of hemorrhage even in the subgroup of medium and large supratentorial AVMs (P = 0.005). There was no difference in draining vein pressure (n = 18) between groups (21 +/- 10 and 19 +/- 11 mm Hg, respectively; P = 0.7812). FMAP (n = 52) was higher in the hemorrhage than in the nonhemorrhage group (44 +/- 13 versus 34 +/- 10 mm Hg; P = 0.0007) but was only weakly related to the size of the lesion (largest dimension) (y = -0.74x + 40; r = 0.09).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Arteriovenous malformation draining vein physiology and determinants of transnidal pressure gradients. The Columbia University AVM Study Project.

Arteriovenous malformation (AVM) draining vein pressure (DVP) may have an influence on both the natural history of the disease and treatment outcome. The purposes of this study were to assess the relationship between DVP and other clinical and physiological variables and to characterize the transmission of arterial pressure across the AVM nidus. DVP measurements were carried out during elective AVM resection with isoflurane/nitrous oxide anesthesia with arterial carbon dioxide pressure of approximately 30 mm Hg. The gradient between the right atrium and operative measurement site was noted. Pre-excision feeding mean arterial pressure and DVP were measured with a 26-gauge needle simultaneously with systemic mean arterial pressure and central venous pressure (CVP). DVP was tested with systemic mean arterial pressure increased to approximately 20 mm Hg with phenylephrine or CVP increased with a Valsalva maneuver. Finally, preresection and postresection DVP values were compared. Relative to the site of measurement, DVP was 7 +/- 5 mm Hg at a CVP of -4 +/- 5 mm Hg (n = 45). There was no influence of presentation, presence of deep venous drainage, size, location, or prior embolization on DVP. In 19 patients, DVP decreased (8 +/- 4 to 5 +/- 3; P < 0.05) whereas CVP increased from pre- to postresection (-4 +/- 5 to -2 +/- 5; P < 0.05). For the phenylephrine challenge (n = 11), there was no difference (P = 0.84) between the delta DVP (2 +/- 1 mm Hg) and the delta CVP (2 +/- 3 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Arteriovenous Malformations↗
PubMed1994

Characterization of arteriovenous malformation feeding vessels by carbon dioxide reactivity.

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 (PetCO2) of about 25 and 35 mm Hg. Carbon dioxide reactivity was calculated as percentage mean blood flow velocity change per mm Hg PetCO2 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.

Adolescent↗
PubMed1993

Transcranial Doppler changes during staged surgical resection of cerebral arteriovenous malformations: a report of three cases.

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.

Adult↗
PubMed1993

Relationship of transcranial Doppler flow velocities and arteriovenous malformation feeding artery pressures.

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.

Adult↗
PubMed1993

Monitoring of intraoperative motor-evoked potentials under conditions of controlled neuromuscular blockade.

Motor-evoked potentials were recorded after electrical spinal cord stimulation in 19 patients undergoing neurosurgical or orthopedic procedures. Anesthesia was maintained with nitrous oxide, opioids, and inhaled anesthetics. Vecuronium was infused sufficient to eliminate 90% of twitch tension. The spinal cord was stimulated using either epidural or subarachnoid electrodes. Compound muscle action potentials were recorded from quadriceps and tibialis anterior muscles. Well-formed, stable motor-evoked potentials were recorded in all but one patient, in whom a preexisting myelopathy was felt to preclude recording. Intraoperative deterioration of motor-evoked potentials occurred in one patient who had a postoperative neurologic deficit. This study demonstrates the feasibility and utility of intraoperative motor tract monitoring using direct spinal cord stimulation. Controlled neuromuscular blockade permits recording of compound muscle action potentials while eliminating patient motor activity that could interfere with surgery.

Action Potentials↗