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David L. Reeves and Howard A. Brown

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Robert D. Brown Jr., David O. Wiebers and Douglas A. Nichols

✓ This long-term follow-up study of 54 patients clarifies the angiographic predictors of intracranial hemorrhage (ICH) and clinical outcome in individuals with unoperated intracranial dural arteriovenous fistulae (AVF's). All of these patients were examined at the Mayo Clinic between 1976 and 1989, and all available cerebral arteriograms were reviewed by a neuroradiologist. Follow-up information was obtained for 52 patients (96%) until death or treatment intervention, or for at least 1 year after diagnosis, with a mean follow-up period of 6.6 years.

Throughout this 6.6-year follow-up period, ICH related to dural AVF occurred in five of the 52 patients, for a crude risk of hemorrhage of 1.6% per year. The risk of hemorrhage at the time of mean follow-up examination was 1.8% per year. Angiographic examination revealed several characteristics that were considered potential predictors of ICH during the follow-up period. Lesions of the petrosal sinus and straight sinus had a higher propensity to bleed, although the small numbers in the series precluded a definite conclusion. A person suffering from a dural AVF with a venous varix on a draining vein had an increased risk of hemorrhage, whereas no hemorrhage was seen in the 20 patients without a varix (p < 0.05). Lesions draining into leptomeningeal veins had an increased occurrence of hemorrhage, although this increased risk was not statistically significant. Patients' initial symptoms were compared to those at follow-up evaluation. Pulsatile tinnitus improved in more than half of the 52 patients, and resolved in 75% of those showing some improvement. Individuals without a sinus or venous outflow occlusion at initial cerebral angiography were more likely to improve or remain stable (89%), whereas patients with an occlusion showed infrequent improvement (11%; p < 0.05).

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Orbital Hemangiopericytoma

Review of the Literature and Report of Four Cases

David N. Brown, Collin S. MacCarty and Edward H. Soule

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Robert D. Brown Jr., David O. Wiebers and Glenn S. Forbes

✓ Among 91 patients with unruptured intracranial arteriovenous malformations (AVM's), 16 patients had 26 unruptured intracranial saccular aneurysms. An actuarial analysis showed the risk of intracranial hemorrhage among patients with coexisting aneurysm and AVM to be 7% per year at 5 years following diagnosis compared to 1.7% for patients with AVM alone. The difference in length of survival free of hemorrhage was significant (log-rank, p < 0.0007). Several angiographic and clinical parameters were investigated to better understand the relationship of these lesions. The aneurysms occurred in similar percentages in patients with small, medium, and large AVM's. Twenty-five aneurysms were on arteries feeding the malformation system, almost equally distributed proximally and distally. Eleven aneurysms were atypical in location, and all arose from primary or secondary branch feeders to the malformation; 24 were on enlarged feeding arteries. Eleven (16%) of the 67 patients with high-flow AVM's had associated aneurysms, compared with five (21%) of the 24 patients with low-flow AVM's. Four (16%) of 25 low-shunt malformations and 12 (18%) of 65 high-shunt malformations had associated aneurysms. All five aneurysms associated with low-shunt malformations were on a direct arterial feeder of the malformation. These data suggest that the intracranial AVM's predispose to aneurysm formation within AVM feeding systems and that the mechanism is not simply based upon the high blood flow or high arteriovenous shunt in these systems.

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Arvin R. Wali, David R. Santiago-Dieppa, Justin M. Brown and Ross Mandeville

OBJECTIVE

Pan–brachial plexus injury (PBPI), involving C5–T1, disproportionately affects young males, causing lifelong disability and decreased quality of life. The restoration of elbow flexion remains a surgical priority for these patients. Within the first 6 months of injury, transfer of spinal accessory nerve (SAN) fascicles via a sural nerve graft or intercostal nerve (ICN) fascicles to the musculocutaneous nerve can restore elbow flexion. Beyond 1 year, free-functioning muscle transplantation (FFMT) of the gracilis muscle can be used to restore elbow flexion. The authors present the first cost-effectiveness model to directly compare the different treatment strategies available to a patient with PBPI. This model assesses the quality of life impact, surgical costs, and possible income recovered through restoration of elbow flexion.

METHODS

A Markov model was constructed to simulate a 25-year-old man with PBPI without signs of recovery 4.5 months after injury. The management options available to the patient were SAN transfer, ICN transfer, delayed FFMT, or no treatment. Probabilities of surgical success rates, quality of life measurements, and disability were derived from the published literature. Cost-effectiveness was defined using incremental cost-effectiveness ratios (ICERs) defined by the ratio between costs of a treatment strategy and quality-adjusted life years (QALYs) gained. A strategy was considered cost-effective if it yielded an ICER less than a willingness-to-pay of $50,000/QALY gained. Probabilistic sensitivity analysis (PSA) was performed to address parameter uncertainty.

RESULTS

The base case model demonstrated a lifetime QALYs of 22.45 in the SAN group, 22.0 in the ICN group, 22.3 in the FFMT group, and 21.3 in the no-treatment group. The lifetime costs of income lost through disability and interventional/rehabilitation costs were $683,400 in the SAN group, $727,400 in the ICN group, $704,900 in the FFMT group, and $783,700 in the no-treatment group. Each of the interventional modalities was able to dramatically improve quality of life and decrease lifelong costs. A Monte Carlo PSA demonstrated that at a willingness-to-pay of $50,000/QALY gained, SAN transfer dominated in 88.5% of iterations, FFMT dominated in 7.5% of iterations, ICN dominated in 3.5% of iterations, and no treatment dominated in 0.5% of iterations.

CONCLUSIONS

This model demonstrates that nerve transfer surgery and muscle transplantation are cost-effective strategies in the management of PBPI. These reconstructive neurosurgical modalities can improve quality of life and lifelong earnings through decreasing disability.

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Stanley A. Baldwin, Isabella Fugaccia, David R. Brown, Laura V. Brown and Stephen W. Scheff

✓ Adult Fisher 344 rats were subjected to a unilateral impact to the dorsal cortex above the hippocampus at 3.5 m/second, resulting in a 2-mm cortical depression. This caused severe cortical damage and neuronal loss in hippocampus subfields CA1, CA3, and hilus. Breakdown of the blood-brain barrier (BBB) was assessed by injecting the protein horseradish peroxidase (HRP) 5 minutes prior to or at various times after injury (5 minutes, 1, 3, 6, and 12 hours, 1, 2, 5, and 10 days). Animals were killed 1 hour after HRP injection and brain sections were reacted with diaminobenzidine to visualize extravascular accumulation of the protein. Maximum staining occurred in animals injected with HRP 5 minutes prior to or 5 minutes after cortical contusion. Staining at these time points was observed in the ipsilateral cortex of the impact area and areas adjacent to it, as well as in the ipsilateral hippocampus. Some modest staining occurred in the dorsal contralateral cortex near the superior sagittal sinus. Cortical HRP staining gradually decreased at increasing time intervals postinjury. By 10 days, no HRP staining was observed in any area of the brain. In the ipsilateral hippocampus, HRP staining was absent by 3 hours postinjury and remained so at the 6- and 12-hour time points. Surprisingly, HRP staining was again observed in the ipsilateral hippocampus 1 and 2 days after cortical contusion, indicating a biphasic opening of the BBB following head trauma and a possible second wave of secondary brain damage days after the contusion injury. These data indicate that regions not initially destroyed by cortical impact, but evidencing BBB breach, may be accessible to neurotrophic factors administered intravenously both immediately and days after brain trauma.

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Mark A. Mahan, Jaime Gasco, David B. Mokhtee and Justin M. Brown

OBJECT

Surgical transposition of the ulnar nerve to alleviate entrapment may cause otherwise normal structures to become new sources of nerve compression. Recurrent or persistent neuropathy after anterior transposition is commonly attributable to a new distal compression. The authors sought to clarify the anatomical relationship of the ulnar nerve to the common aponeurosis of the humeral head of the flexor carpi ulnaris (FCU) and flexor digitorum superficialis (FDS) muscles following anterior transposition of the nerve.

METHODS

The intermuscular septa of the proximal forearm were explored in 26 fresh cadaveric specimens. The fibrous septa and common aponeurotic insertions of the flexor-pronator muscle mass were evaluated in relation to the ulnar nerve, with particular attention to the effect of transposition upon the nerve in this region.

RESULTS

An intermuscular aponeurosis associated with the FCU and FDS muscles was present in all specimens. Transposition consistently resulted in angulation of the nerve during elbow flexion when this fascial septum was not released. The proximal site at which the nerve began to traverse this fascial structure was found to be an average of 3.9 cm (SD 0.7 cm) from the medial epicondyle.

CONCLUSIONS

The common aponeurosis encountered between the FDS and FCU muscles represents a potential site of posttransposition entrapment, which may account for a subset of failed anterior transpositions. Exploration of this region with release of this structure is recommended to provide an unconstrained distal course for a transposed ulnar nerve.

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Nnenna Mbabuike, Kelly Gassie, Benjamin Brown, David A. Miller and Rabih G. Tawk

OBJECTIVE

Tandem occlusions continue to represent a major challenge in patients with acute ischemic stroke (AIS). The anterograde approach with proximal to distal revascularization as well as the retrograde approach with distal to proximal revascularization have been reported without clear consensus or standard guidelines.

METHODS

The authors performed a comprehensive search of the PubMed database for studies including patients with carotid occlusions and tandem distal occlusions treated with endovascular therapy. They reviewed the type of approach employed for endovascular intervention and clinical outcomes reported with emphasis on the revascularization technique. They also present an illustrative case of AIS and concurrent proximal cervical carotid occlusion and distal middle cerebral artery occlusion from their own experience in order to outline the management dilemma for similar cases.

RESULTS

A total of 22 studies were identified, with a total of 790 patients with tandem occlusions in AIS. Eleven studies used the anterograde approach, 3 studies used the retrograde approach, 4 studies used both, and in 4 studies the approach was not specified. In the studies that reported Thrombolysis in Cerebral Infarction (TICI) grades, an average of 79% of patients with tandem occlusions were reported to have an outcome of TICI 2b or better. One study found good clinical outcome in 52.5% of the thrombectomy-first group versus 33.3% in the stent-first group, as measured by the modified Rankin Scale (mRS). No study evaluated the difference in time to reperfusion for the anterograde and retrograde approach and its association with clinical outcome. The patient in the illustrative case had AIS and tandem occlusion of the internal carotid and middle cerebral arteries and underwent distal revascularization using a Solitaire stent retrieval device followed by angioplasty and stent treatment of the proximal cervical carotid occlusion. The revascularization was graded as TICI 2b; the postintervention National Institutes of Health Stroke Scale (NIHSS) score was 17, and the discharge NIHSS score was 7. The admitting, postoperative, and 30-day mRS scores were 5, 1, and 1, respectively.

CONCLUSIONS

In stroke patients with tandem occlusions, distal to proximal revascularization represents a reasonable treatment approach and may offer the advantage of decreased time to reperfusion, which is associated with better functional outcome. Further studies are warranted to determine the best techniques in endovascular therapy to use in this subset of patients in order to improve clinical outcome.

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Jeffrey A. Brown, Christopher J. Chittum, David Sabol and Jan J. Gouda

The technique of percutaneous balloon compression for treatment of trigeminal neuralgia is demonstrated by using embedded audiovisual kernels. A text-based description with linked images is also provided to accomodate varying computer hardware capabilities. A new needle system for guiding the balloon catheter to the entrance of Meckel's cave and a balloon pressure monitoring system for the procedure is described and demonstrated. Results from a series of 141 consecutive patients treated during the period between 1983 and 1995 indicate an initial success rate of 92%. Fifty-seven percent of patients have postoperative numbness, which is described as mild to moderate by 94% of them. Sixteen percent have ipsilateral masseter-pterygoid weakness after compression. The overall recurrence rate is 26%. A Kaplan-Meier survival curve indicates that 60% of patients are pain free 8 years after surgery without recurrence requiring reoperation. The recurrence rate does not significantly differ from patients with first division pain to patients without first division involvement. An absent corneal reflex has not occurred, nor has anesthesia dolorosa. Balloon compression injures the myelinated fibers that mediate the “trigger” to the lancinating pain of trigeminal neuralgia. Because the corneal reflex is mediated by unmyelinated fibers, selective, monitored compression of myelinated fibers should preserve the corneal reflex when first division pain is present.

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Thanh G. Phan, John Huston III, Robert D. Brown Jr., David O. Wiebers and David G. Piepgras

Object. The goal of this study was to determine the frequency of enlargement of unruptured intracranial aneurysms by using serial magnetic resonance (MR) angiography and to investigate whether aneurysm characteristics and demographic factors predict changes in aneurysm size.

Methods. A retrospective review of MR angiograms obtained in 57 patients with 62 unruptured, untreated saccular aneurysms was performed. Fifty-five of the 57 patients had no history of subarachnoid hemorrhage. The means of three measurements of the maximum diameters of these lesions on MR source images defined the aneurysm size. The median follow-up period was 47 months (mean 50 months, range 17–90 months).

No aneurysm ruptured during the follow-up period. Four patients (7%) harbored aneurysms that had increased in size. No aneurysms smaller than 9 mm in diameter grew larger, whereas four (44%) of the nine aneurysms with initial diameters of 9 mm or larger increased in size. Factors that predicted aneurysm growth included the size of the lesion (p < 0.001) and the presence of multiple lobes (p = 0.021). The location of the aneurysm did not predict an increased risk of enlargement.

Conclusions. Patients with medium-sized or large aneurysms and patients harboring aneurysms with multiple lobes may be at increased risk for aneurysm growth and should be followed up with MR imaging if the aneurysm is left untreated.