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Biomedical subjects

J Pile-Spellman

Publications and source records attributed to J Pile-Spellman.

At least 73 records · Page 4Linked to original sources
PubMed1996

The effect of arteriovenous malformations on the distribution of intracerebral arterial pressures.

PURPOSE: To examine the distribution of arterial hypotension surrounding arteriovenous malformations (AVMs) using a standardized system of vascular zones. METHODS: Mean arterial pressures were recorded during superselective cerebral angiography in 96 patients with AVMs (before they underwent liquid polymer embolization) with the use of a system of vascular zones: E = extracranial internal carotid or vertebral artery; I = intracranial internal carotid or basilar artery; T = transcranial Doppler insonation site (A1, P1, M1); H = halfway to feeder, perfusing normal tissue and shunt; and F = feeder at site of N-butyl cyanoacrylate injection. Distal arterial pressure was measured contralateral to the AVM in an additional 12 patients (zone Hc). RESULTS: Zone pressures (mm Hg +/- SD) were E = 76 +/- 16, I = 69 +/- 15, T = 59 +/- 16, H = 47 +/- 13, and F = 39 +/- 15 mm Hg. Vessel/systemic ratios for the zones were E = 0.97 +/- 0.05, I = 0.86 +/- 0.08, T = 0.75 +/- 0.12, H = 0.61 +/- 0.13, and F = 0.50 +/- 0.18. Measurements were obtained in 29 patients in all five zones and all had similar mean values. Zone Hc pressure was 66 +/- 17 mm Hg and the ratio was 0.78 +/- 0.12, both greater than zone H values. CONCLUSION: Using a standardized system of anatomic vascular zones, we found a progressive and significant decrease in intracerebral arterial pressure in patients with AVMs that proceeded from the circle of Willis to the nidus. Large areas of parenchyma sharing the same parent arterial supply may be subject to chronic hypotension.

Adult↗
PubMed1996

Cerebral SPECT imaging: effect on clinical management.

This study, performed in 94 consecutive patients referred for evaluation, demonstrates the clinical utility of cerebral SPECT imaging. In a significant percentage of patients (47%), the additional information provided by SPECT resulted in an alteration in clinical management. Long-term follow-up will be necessary to determine the effect of these management decisions on patient outcome.

Brain↗
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↗
PubMed1995

Adaptive changes of autoregulation in chronic cerebral hypotension with arteriovenous malformations: an acetazolamide-enhanced single-photon emission CT study.

PURPOSE: To evaluate the relationship among feeding arterial pressure, lesion size, and perfusion in cerebral cortex adjacent to cerebral arteriovenous malformations (AVMs). METHODS: Eleven patients with hemispheric AVMs underwent 99mTc hexamethyl-propyleneamine oxime single-photon emission CT before and after 1 g of acetazolamide was administered intravenously. AVM volume was estimated from MR dimensions and measured according to the method described by Pasqualin. Pressure measurements were obtained in arteries feeding the cortex adjacent to AVMs. Single-photon emission CT regions of interest were defined in cortex adjacent to the AVM and compared with contralateral regions using the Mountz method to estimate a baseline and dynamic (acetazolamide-challenged) perfusion defect volume. RESULTS: Eight of 11 patients had baseline perfusion defects, but these defects were unrelated to feeding artery pressures (y = -.06x + 9.92, r2 = .04) or the dynamic change in defect volume after acetazolamide administration (y = .01x + .02, r2 = .002). However, there was a correlation between AVM volume and the baseline defect volume (y = .75x - 1.9, r2 = .76). Five patients had increased defect volume after acetazolamide administration; 5 patients had either no change in or improvement of perfusion. Dynamic changes in defect volume were related to feeding artery pressures. CONCLUSION: Perilesional baseline perfusion defects appear to be related to lesion size and not to local arterial pressure. Cerebrovascular reserve generally was preserved, and perfusion defects appeared to be more pronounced with lower arterial pressures in feeding vessels. Although vasodilatory testing can unmask hemodynamic failure with severe local hypotension, baseline perfusion defects near the lesion and distant perfusion changes are more likely attributable to other causes such as mass-related or neurogenic changes.

Acetazolamide↗
PubMed1994

A computer simulation of the haemodynamic effects of intracranial arteriovenous malformation occlusion.

To study the effect of AVM occlusion on cerebrovascular haemodynamics, a simplified model was simulated consisting of a feeding artery supplying a capillary bed in parallel with a fistula-like malformation, both emptying into a draining vein. An electrical circuit analogue of the physiologic system was developed using lumped proximal and distal pressure dependent resistances, and capacitors representing vascular compliance. Autoregulation was introduced as a pressure varying precapillary arteriolar resistance. Equations derived from the circuit model were simulated using a graphical modeling program. The model successfully simulates phenomena angiographically observed during embolization procedures. Fistula pressure is shown to rapidly fall following proximal AVM occlusion, in contrast to a marked rise seen with distal occlusion, which is associated with biphasic flow into and out of the fistula and the arterial feeder. The model predicts an increase in capillary pressure and capillary flow which, depending on the magnitude of the flow increase and the state of autoregulation, may result either in reversal of ischaemia or hyperperfusion injury. Vascular overload is predicted in the absence of autoregulation. There is, however, little potential for vascular overload when autoregulation is intact. The model represents a first step in the mathematical characterization of the phenomenon of hyperperfusion following AVM occlusion.

Arterial Occlusive Diseases↗
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

Usefulness of non-detachable balloons in endovascular treatment for cerebral aneurysms.

An endovascular non-detachable balloon technique was used to treat 14 patients with cerebral aneurysms. Eight patients presented with subarachnoid hemorrhage, and six others presented with headache or mass effect. Six aneurysms were located in the anterior circulation and eight in the posterior circulation. Seven aneurysms were giant, three were large, and four were small. All target aneurysms or vessels were occluded successfully. Parent vessel was successfully spared in seven cases. There were no procedural complications related to the non-detachable nature of the balloon used. Follow-up angiography detected refilling of aneurysms in three of 11 patients, two with small ruptured aneurysms that bled again following partial deflation or balloon movement. The other aneurysms tested remained occluded, as demonstrated on follow-up angiograms, for up to 15 months. Outcomes were good to excellent in 10 patients, poor in one, and three died. Non-detachable balloons might be preferred for treatment of certain types of cerebral aneurysms including those where intraaneurysmal maneuvers might be considered dangerous, for example, with recent bleeding or intraluminal fresh clots; where precise placement of the balloon is required, for example, in the vicinity of perforators or collaterals emerging near the neck; and where detachment could be dangerous or difficult in broad neck and fusiform aneurysms or in tortuous parent vessels.

Adult↗
PubMed1994

Surgical management of unruptured intracranial aneurysms.

The surgical management of patients with unruptured intracranial aneurysms continues to be controversial. The criteria for withholding treatment or choosing between endovascular embolization and conventional microsurgery are not well delineated. The present study analyzes the morbidity and mortality that can be expected with modern surgical management of unruptured aneurysms, and therefore serves as a point of reference for clinical decision-making in this group of patients. A total of 202 consecutive operations for attempted clipping of unruptured intracranial aneurysms are reported. Subarachnoid hemorrhage from another aneurysm was the most common presentation (55 cases). Thirty-seven patients presented with headache, 36 with mass effect from the aneurysm, and 19 with embolic events; 11 aneurysms were associated with an arteriovenous malformation, 10 caused seizures, and 34 were incidental findings. Excellent or good outcome was achieved in 100% of patients with aneurysms less than 10 mm in diameter, 95% with aneurysms 11 to 25 mm, and 79% with aneurysms greater than 25 mm. Except for giant basilar aneurysms, size (and not location) of the aneurysm was the key predictor of risk for surgical morbidity. These data may be useful when discussing with patients the risk:benefit ratio of choosing between conservative management, endovascular embolization, and microsurgical clipping.

Adolescent↗
PubMed1994

Transethmoidal transsphenoidal approach for embolization of a carotid-cavernous fistula. Case report.

The authors describe a case of carotid-cavernous fistula that was not treatable by the standard interventional neuroradiological techniques of transarterial or transvenous occlusion of the fistula because access was blocked by prior trapping procedures. Access to the venous side of the fistula was gained by means of a transethmoidal transsphenoidal exposure, making it possible to embolize the lesion with coils. The details of this approach are described.

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

Extracranial vertebral artery pseudoaneurysm presenting as subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: True aneurysms of the extracranial vertebral artery are rare. The usual pathogenesis of aneurysms in this location is either penetrating or blunt trauma with resultant pseudoaneurysm formation. We report a postpartum patient with a presumed traumatic pseudoaneurysm of the extracranial vertebral artery presenting with subarachnoid hemorrhage. CASE DESCRIPTION: A 41-year-old woman had three episodes of neck stiffness 1 month after an uncomplicated vaginal delivery. The last episode, 3 days before admission, was accompanied by intense neck and head pain and paresthesias that extended into the left arm, thumb, and forefinger. RESULTS: Lumbar puncture showed subarachnoid hemorrhage. Angiography revealed a left vertebral artery dissection from C6-7 to C3 with pseudoaneurysm at C5-6. Computed tomography demonstrated impingement of the C6 root at the foramen by this lesion. The lesion was successfully treated by balloon occlusion of the vertebral artery. CONCLUSION: We present a patient with an extracranial vertebral pseudoaneurysm with subarachnoid hemorrhage and cervical root impingement. To our knowledge, this is the first case of such a lesion presenting as subarachnoid hemorrhage. The lesion was successfully treated using endovascular techniques.

Adult↗
PubMed1993

[Posterior fossa dural arteriovenous fistula with isolated sinus segment].

Radiological and clinical analysis was performed in 5 patients with posterior fossa dural arteriovenous fistulas (DAVFs) with isolated sinus segment due to sinus thrombosis, and their patho physiological, diagnostic, and therapeutic concerns were discussed. Patients ranged in age from 36 to 73 years old with a mean of 57 years and included 2 males and 3 females. Two patients presented with ataxia, one with ataxia and bruit, one with atypical facial pain, and one with parietal dysfunction. One patient had a history of hemorrhagic event. DAVFs were located at transverse-sigmoid sinus (3 cases), superior petrosal sinus (1 case), and straight sinus (1 case). They were fed by many branches of external carotid artery including middle meningeal artery, ascending pharyngeal artery, posterior auricular artery, occipital artery, meningeal branches of vertebral artery and posterior cerebral artery, and meningohypophyseal trunk of internal carotid artery. Shunt flow drained into contralateral transverse-sigmoid or supratentorial sinuses via the isolated venous segment through markedly dilated cortical and/or deep venous systems, which caused altered normal venous drainage pattern and venous hypertension. Transarterial embolization in multiple stages (mean 3.4) using n-butyl cyanoacrylate (NBCA) could alleviate symptoms in all cases. DAVFs were almost totally obliterated in 3 patients. Further embolization in one case, and surgical excision in one case were planed because of some residual dilated cortical venous drainage. Posterior fossa DAVFs with isolated sinus segment accompany markedly dilated cortical and/or deep venous systems. They could cause cerebellar, brainstem, or cranial nerve dysfunctions, and sometimes present distant supratentorial symptoms or hydrocephalus due to abnormal venous drainage and venous hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The current surgical management of carotid body paragangliomas.

To determine if recent trends in evaluation and therapy have contributed to the successful surgical management of carotid body paragangliomas, we reviewed our experience over the past decade. Nineteen carotid body paragangliomas were identified in 17 patients. Eleven patients underwent complete, preoperative embolization of their afferent arteries with one complication. Calculated carotid body paragangliomas surface areas did not differ between the embolized 64.6 +/- 43.3 cm2 and nonembolized 63.0 +/- 57.9 cm2 lesions. Intraoperative blood loss was lower (p = 0.02) in the patients treated with embolization (372 +/- 213 ml) compared with their cohorts (609 +/- 564 ml). However, the operative times were equivalent 4.1 hours versus 4.5 hours in both groups. Intraoperative electroencephalographic (EEG) monitoring was used in 10 patients; in one patient the EEG indicated intraoperative thrombosis of the carotid artery, which was successfully treated by thrombectomy without complications. Two patients required carotid bifurcation resection and vascular reconstruction to remove the entire tumor; a late stroke manifested by contralateral hand weakness developed in one of these patients. The incidence of cranial nerve injury was low at 16%, with one transient ramus mandibularis paresis and two instances of vocal cord dysfunction. Two additional patients had a postoperative Horner's syndrome. We conclude that by diminishing intraoperative blood loss through complete and careful preoperative embolization and use of intraoperative EEG monitoring along with careful surgical technique, the complications associated with this challenging operation are facilitated and diminished.

Adult↗