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Biomedical subjects

J M Zabramski

Publications and source records attributed to J M Zabramski.

At least 19 recordsLinked to original sources
PubMed2001

Assessment of silent embolism from carotid endarterectomy by use of diffusion-weighted imaging: work in progress.

BACKGROUND AND PURPOSE: Transcranial Doppler studies have suggested that microemboli are released into the arterial circulation during the majority of carotid endarterectomy (CEA) procedures. This, together with the observation that neuropsychological performance may decline postoperatively, has led to concern that cerebral infarction may occur unrecognized during CEA. Our objective was to examine this risk with diffusion-weighted imaging, a technique that is highly sensitive to acute cerebral infarction. METHODS: Eighteen participants (median age, 68 years; age range, 56-87 years) were assessed with diffusion-weighted imaging and the National Institutes of Health Stroke Scale before and after CEA. Imaging was performed using single-shot echo-planar imaging with a maximum diffusion sensitivity of b = 1000 s/mm(2) applied to three orthogonal planes. Preoperative imaging was performed a median of 2.5 hours before surgery (range, 0.5-12.5 hours) and 15 hours after surgery (range, 1.5-58.5 hours). Two neuroradiologists independently interpreted the diffusion-weighted images, blinded to operative status and clinical findings. RESULTS: There was no diffusion-weighted imaging evidence of silent embolism in this series of 18 participants (95% confidence interval limits, 0 to 10%). Clinical complications were confined to one case of confusion occurring after CEA; the diffusion-weighted imaging results were normal in this case. CONCLUSION: There is no evidence from our series that silent cerebral infarction is a common occurrence during CEA. These data provide further support for the safety of CEA.

Aged↗
PubMed2000

Animal model for cerebral arteriovenous malformation.

BACKGROUND: The present study was conducted to establish an animal model for the investigation of the pathophysiology and haemodynamics of cerebral arteriovenous malformation (AVM) but also to assess therapeutic aspects. METHOD: For anatomic and haemodynamic reasons, dogs were chosen as the animal model. An arteriovenous fistula was created by interposing a segment of the superficial temporal artery between one of the main branches of the middle cerebral artery and the dorsal sagittal sinus. A temporal muscle graft supplied by this artery was implanted intracerebrally in the ischaemic area. FINDINGS: The angiographic and histopathologic findings obtained in the animal model are comparable with the situation found in intracerebral AVM in humans. INTERPRETATION: The animal model of intracerebral AVM established in this study allows for further investigation of the pathophysiology and dynamics of this disorder. It may help to develop better therapeutic options and thus improve the prognosis of affected patients.

Animals↗
PubMed2000

The efficacy and cost of prophylactic and perioprocedural antibiotics in patients with external ventricular drains.

OBJECTIVE: Prophylactic antibiotics are routinely administered to patients with external ventricular drains (EVDs); however, no conclusive evidence supports this practice. This study compared the efficacy and cost of prophylactic and periprocedural antibiotics in patients with EVDs. METHODS: We reviewed the charts of 308 patients who had an EVD in place for 3 or more days between January 1996 and June 1997. Patients with EVDs placed for shunt infections or meningitis were excluded. A standard protocol was used to insert and monitor EVDs. Catheters were left in place as long as clinically indicated and changed only if they malfunctioned. Cerebrospinal fluid cultures were obtained twice weekly. Prophylactic antibiotics were used at the discretion of the attending neurosurgeon. Patients were divided into two groups: Group A comprised 209 patients who received prophylactic antibiotics for the duration of the EVD (intravenously administered cefuroxime, 1.5 g every 8 h); Group B comprised 99 patients who received only periprocedural antibiotics (intravenously administered cefuroxime, 1.5 g every 8 h, three or less doses). RESULTS: Although there were significantly more males in Group A than in Group B, the two groups were otherwise well matched, with no significant differences in age, indications, or duration of EVD placement. The overall rate of ventriculitis was 3.9%. The infection rates for Group A (3.8%) and Group B (4.0%) were almost identical. CONCLUSION: Prophylactic antibiotics did not significantly reduce the rate of ventriculitis in patients with EVDs, and they may select for resistant organisms. Discontinuing the use of prophylactic antibiotics for EVDs at the authors' institution would save approximately $80,000 per year in direct drug costs.

Adult↗
PubMed2000

Subfascial and submuscular methods of temporal muscle dissection and their relationship to the frontal branch of the facial nerve. Technical note.

The microsurgical anatomy of the temporal and zygomatic branches of the facial nerve are presented along with related local vasculature (frontal and parietal branches of the superficial temporal artery [STA]) as encountered when using subfascial and submuscular temporal muscle dissection techniques for anterolateral craniotomies. Twenty sides were studied in 10 cadaveric specimens that had been previously injected with latex. The rami of the temporal and zygomatic branches of the facial nerve and branches of the STA were dissected out through pterional and orbitozygomatic approaches by using a submuscular or subfascial temporal muscle dissection technique. The three rami of the temporal branch of the facial nerve (the auricularis, frontalis, and orbicularis) were found to run within the galeal plane of the scalp. The zygomatic branch of the facial nerve was found to course deeper than the most caudal extension of the galea, known as the superficial musculoaponeurotic layer. The frontal branch of the STA served as an important landmark for the subfascial or submuscular dissections because excessive reflection of the scalp flap inferior to the level of this vessel would inadvertently injure the frontalis branch of the facial nerve. Subfascial and submuscular dissections of the temporal muscle offer an alternative to the interfascial technique during anterolateral craniotomies. Scalp and temporal dissection performed with careful attention to anatomical landmarks (frontal branch of the STA and the suprafascial fat pad) provides a safe and expeditious alternative to the traditional interfascial technique.

Adipose Tissue↗
PubMed1999

Mutations in the gene encoding KRIT1, a Krev-1/rap1a binding protein, cause cerebral cavernous malformations (CCM1).

Cerebral cavernous malformations (CCM) are congenital vascular anomalies of the brain that can cause significant neurological disabilities, including intractable seizures and hemorrhagic stroke. One locus for autosomal dominant CCM ( CCM1 ) maps to chromosome 7q21-q22. Recombination events in linked family members define a critical region of approximately 2 Mb and a shared disease haplotype associated with a presumed founder effect in families of Mexican-American descent points to a potentially smaller region of interest. Using a genomic sequence-based positional cloning strategy, we have identified KRIT1, encoding a protein that interacts with the Krev-1/rap1a tumor suppressor, as the CCM1 gene. Seven different KRIT1 mutations have been identified in 23 distinct CCM1 families. The identical mutation is present in 16 of 21 Mexican-American families analyzed, substantiating a founder effect in this population. Other Mexican-American and non-Hispanic Caucasian CCM1 kindreds harbor other KRIT1 mutations. Identification of a common Mexican-American mutation has potential clinical significance for presymptomatic diagnosis of CCM in this population. In addition, these data point to a key role for the Krev-1/rap1a signaling pathway in angiogenesis and cerebrovascular disease.

Blood Vessels↗
PubMed1999

Patients with spinal cord cavernous malformations are at an increased risk for multiple neuraxis cavernous malformations.

OBJECTIVE: To determine the prevalence of multiple neuraxis cavernous malformations in patients who initially presented with intramedullary spinal cord (IMSC) cavernous malformations without knowledge of cavernous malformations elsewhere in the neuraxis. METHODS: Hospital records and radiographic files were analyzed for 17 patients who subsequently underwent surgical resection of an IMSC cavernous malformation (histologically proven) and also underwent brain magnetic resonance imaging studies. These 17 patients represented a subset of 32 patients who underwent surgical resection of an IMSC cavernous malformation during the same period. RESULTS: Of 17 patients, 8 (47%) harbored multiple cavernous malformations. This group was composed of five women and three men (mean age, 35.9 yr). There were four Caucasian and four Hispanic patients. CONCLUSION: The prevalence of multiple cavernous malformations in the neuraxis seems to be increased in patients who harbor IMSC cavernous malformations. This finding has important implications for the evaluation and management of these patients and, in some cases, their family members.

Adolescent↗
PubMed1999

Cavernous malformations of the brainstem: experience with 100 patients.

OBJECT: In this study the authors review surgical experience with cavernous malformations of the brainstem (CMBs) in an attempt to define more clearly the natural history, indications, and risks of surgical management of these lesions. METHODS: The authors retrospectively reviewed the cases of 100 patients (38 males and 62 females; mean age 37 years) harboring 103 lesions at treated a single institution between 1984 and 1997. Clinical histories, radiographs, pathology records, and operative reports were evaluated. The brainstem lesions were distributed as follows: pons in 39 patients, medulla in 16, midbrain in 16, pontomesencephalic junction in 15, pontomedullary junction in 10, midbrain-hypothalamus/thalamus region in two patients, and more than two brainstem levels in five. The retrospective annual hemorrhage rate was most conservatively estimated at 5% per lesion per year. Standard skull base approaches were used to resect lesions in 86 of the 100 patients. Intraoperatively, all 86 patients were found to have a venous anomaly in association with the CMB. Follow up was available in 98% (84 of 86) of the surgical patients. Of these, 73 (87%) were the same or better after surgical intervention, eight (10%) were worse, and three (4%) died. Two surgical patients were lost to follow-up review. Incidences of permanent or severe morbidity occurred in 10 (12%) of the surgically treated patients. The average postoperative Glasgow Outcome Scale score for surgically treated patients was 4.5, with a mean follow-up period of 35 months. CONCLUSIONS: The natural history of CMBs is worse than that of cavernous malformations in other locations. These CMBs can be resected using skull base approaches, which should be considered in patients with symptomatic hemorrhage who harbor lesions that approach the pial surface. Venous anomalies are always associated with CMBs and must be preserved.

Adolescent↗
PubMed1999

Pathology of cerebral vascular malformations.

The gross and microscopic features of cerebral arteriovenous malformations, cavernous malformations, capillary telangiectases, and venous malformations are compared and contrasted. The pathogenesis of these lesions and possible interrelationships suggested by transitional lesions are also reviewed.

Brain Neoplasms↗
PubMed1998

Characterization of neuroprotection from excitotoxicity by moderate and profound hypothermia in cultured cortical neurons unmasks a temperature-insensitive component of glutamate neurotoxicity.

Although profound hypothermia has been used for decades to protect the human brain from hypoxic or ischemic insults, little is known about the underlying mechanism. We therefore report the first characterization of the effects of moderate (30 degrees C) and profound hypothermia (12 degrees to 20 degrees C) on excitotoxicity in cultured cortical neurons exposed to excitatory amino acids (EAA; glutamate, N-methyl-D-aspartate [NMDA], AMPA, or kainate) at different temperatures (12 degrees to 37 degrees C). Cooling neurons to 30 degrees C and 20 degrees C was neuroprotective, but cooling to 12 degrees C was toxic. The extent of protection depended on the temperature, the EAA receptor agonist employed, and the duration of the EAA challenge. Neurons challenged briefly (5 minutes) with all EAA were protected, as were neurons challenged for 60 minutes with NMDA, AMPA, or kainate. The protective effects of hypothermia (20 degrees and 30 degrees C) persisted after rewarming to 37 degrees C, but rewarming from 12 degrees C was deleterious. Surprisingly, however, prolonged (60 minutes) exposures to glutamate unmasked a temperature-insensitive component of glutamate neurotoxicity that was not seen with the other, synthetic EAA; this component was still mediated via NMDA receptors, not by ionotropic or metabotropic non-NMDA receptors. The temperature-insensitivity of glutamate toxicity was not explained by effects of hypothermia on EAA-evoked [Ca2+]i increases measured using high- and low-affinity Ca2+ indicators, nor by effects on mitochondrial production of reactive oxygen species. This first characterization of excitotoxicity at profoundly hypothermic temperatures reveals a previously unnoticed feature of glutamate neurotoxicity unseen with the other EAA, and also suggests that hypothermia protects the brain at the level of neurons by blocking, rather than slowing, excitotoxicity.

Animals↗
PubMed1998

Hypothermic circulatory arrest in neurovascular surgery: evolving indications and predictors of patient outcome.

OBJECTIVE: One of the largest contemporary neurosurgical experiences with hypothermic circulatory arrest was analyzed for trends in patient selection and clinical variables affecting outcome. METHODS: During a 12-year period, 60 patients underwent 62 circulatory arrest procedures: 54 had posterior circulation aneurysms, 4 had anterior circulation aneurysms, and 2 had other lesions (hemangioblastoma and vertebral artery atherosclerosis). RESULTS: The surgical morbidity and mortality rates associated with hypothermic circulatory arrest were 13.3 and 8.3%, respectively. At late follow-up, 76% of the patients had good outcomes (Glasgow Outcome Scale scores of 1 and 2), 5% had poor outcomes (Glasgow Outcome Scale scores of 3 and 4), and 18% had died. After 1992, circulatory arrest was limited to posterior circulation aneurysms and included increasing numbers of basilar trunk aneurysms. Patient outcome correlated with preoperative neurological condition (admission Glasgow Coma Scale score, P < 0.001; Hunt and Hess grade, P = 0.037; and age, P = 0.007). Preservation of perforating arteries was paramount to achieving a good outcome (P = 0.005); duration of circulatory arrest was not. CONCLUSION: Current indications for hypothermic circulatory arrest include only giant and complex posterior circulation aneurysms that cannot be treated using conventional techniques or that recur after endovascular coiling. Surgical morbidity and mortality rates reflect the increasing complexity of the aneurysms treated but are still more favorable than the natural history of these lesions. This experience demonstrates that management in specialized neurovascular centers can minimize the morbidity associated with circulatory arrest so that it remains a viable treatment option for complex posterior circulation aneurysms.

Adolescent↗
PubMed1998

Long-term graft patency rates and clinical outcomes after revascularization for symptomatic traumatic internal carotid artery dissection.

INTRODUCTION: Surgical management of traumatic internal carotid artery (ICA) dissection remains controversial. Therefore, the delayed outcomes and graft patency rates of patients who underwent bypass procedures for symptomatic traumatic ICA dissection were studied. METHODS: Between September 1989 and August 1996, 13 patients (9 male and 4 female patients; mean age, 30.6 yr) underwent 16 revascularization procedures for symptomatic traumatic ICA dissection. The duration of clinical follow-up averaged 47.3 months (range, 12-94 mo) from the date of diagnosis. The duration of radiographic follow-up (catheter or magnetic resonance angiography, duplex Doppler ultrasonography) averaged 24 months (range, 12-60 mo). RESULTS: ICA dissection was caused by blunt (n = 11) or penetrating trauma (n = 2). Associated angiographic abnormalities included seven ipsilateral ICA occlusions, six dissecting aneurysms, two carotid-cavernous fistulae, and six contralateral traumatic ICA dissections. Patients requiring early revascularization (n = 6) underwent bypass procedures an average of 19.2 days after their injuries. Medically managed patients who developed ischemia later were revascularized a mean of 7.8 months after injury. The mean Glasgow Coma Scale score at the time of presentation was 10 (range, scores of 6-15), and the mean Glasgow Coma Scale score before revascularization was 14 (range, scores of 9-15). There were 14 saphenous vein ICA bypasses (8 cervical-to-petrous, 3 cervical-to-middle cerebral artery, 3 petrous-to-supraclinoid) and 2 superficial temporal artery-to-middle cerebral artery bypasses. There was one early postoperative graft occlusion, which responded to surgical thrombectomy. One patient with multiple other traumatic injuries died as a result of a pulmonary embolus 12 months after revascularization. All remaining patients had Glasgow Outcome Scale scores of 5, with patent bypass grafts confirmed during follow-up. CONCLUSION: Revascularization for persistently symptomatic traumatic ICA dissection eliminated ischemia and was associated with excellent long-term outcomes and graft patency rates.

Adolescent↗
PubMed1998

Orbitozygomatic craniotomy. Technical note.

The orbitozygomatic approach provides wide, multidirectional access to the anterior and middle cranial fossae, as well as to the upper third of the posterior fossa and clivus. The authors describe technical details of the surgical approach as it has evolved over 3.5 years of experience in 83 consecutive cases. This modified technique eliminates the need for bone reconstruction of the orbital walls to prevent enophthalmos and minimizes the risk of injury to the frontal branch of the facial nerve. At a follow-up evaluation after a period averaging 14 months, all patients were pleased with the cosmetic results of this approach.

Brain Neoplasms↗
PubMed1998

Rupture of a previously documented small asymptomatic intracranial aneurysm in a patient with autosomal dominant polycystic kidney disease. Case report.

Intracranial aneurysms are common extrarenal manifestations of autosomal dominant polycystic kidney disease (ADPKD). Although their natural history is not completely understood, small asymptomatic intracranial aneurysms in patients with ADPKD often are not treated but are followed with serial magnetic resonance (MR) angiography. The authors report the unique case of a patient with ADPKD who bled from a previously documented asymptomatic 3-mm intracranial aneurysm. This 42-year-old man with ADPKD suffered a subarachnoid hemorrhage (SAH) from a 7-mm left pericallosal artery aneurysm. This aneurysm was clipped and the patient made an excellent recovery. An irregular asymptomatic 3-mm right middle cerebral artery (MCA) aneurysm had also been demonstrated on angiography. While the patient was considering elective surgery for the MCA aneurysm, he suffered a hemorrhage from this lesion 10 weeks after the initial SAH. The aneurysm was clipped and the patient made a satisfactory recovery (he was moderately disabled). In this report the authors indicate that small asymptomatic intracranial aneurysms are not always innocuous in patients with ADPKD, and they suggest that treatment should be strongly considered for these lesions in this group of patients when there is a history of SAH or the aneurysm is irregular in appearance. Because MR angiography studies may not adequately define the configuration of small aneurysms and irregularity may easily be missed, conventional angiography is recommended for patients with ADPKD who are found to have an intracranial aneurysm on screening with MR angiography.

Adult↗
PubMed1998

Brain protection for cerebral aneurysm surgery.

The modern management of patients undergoing surgery for intracranial aneurysm often includes temporary periods of cerebral ischemia to minimize the risks final dissection and clipping or to allow vascular reconstruction. This article reviews the concepts of ischemic thresholds and examines the effects of the physiologic variables that may affect outcome from an ischemic episode. The protective agents presently available and the agents in development that may limit the extent of ischemic injury are reviewed extensively as well.

Brain Ischemia↗
PubMed1997

Treatment for intracranial dural arteriovenous malformations: a meta-analysis from the English language literature.

OBJECTIVE: The treatment of intracranial dural arteriovenous malformations (DAVMs) remains problematic. Options include ligature of feeding vessels, endovascular procedures, surgical obliteration, or a combination of the latter two. We conducted a meta-analysis of the English language literature on DAVMs to determine the most effective treatment option related to location and angiographic characteristics. METHODS: The criteria for inclusion were pre- and post-treatment angiography, a description of the type of treatment, and clinical outcome. The analysis included a total of 258 patients, 248 from a review of 223 published articles and 10 from the authors' series. DAVMs were divided into six categories by location, and the results of treatment were compared based on obliteration rates using chi 2 analysis. RESULTS: In transverse-sigmoid sinus DAVMs (n = 64), combined therapy (endovascular plus surgical treatment) proved significantly more effective than either therapy alone (P < 0.01). For lesions of the tentorial incisura (n = 66), combined therapy and surgical obliteration alone proved superior to embolization (P < 0.001). For lesions of the cavernous sinus (n = 67), treatment was primarily endovascular, with success rates of 62 to 78% for transarterial and transvenous approaches, respectively. In the anterior fossa (n = 23), surgical obliteration was highly effective, with a success rate of 95%. The small number of cases in both the superior sagittal sinus (n = 28) and middle fossa (n = 10) regions, precluded any statistical analysis. Finally, simple ligature of feeding vessels produced success rates of only 0 to 8% and can no longer be recommended. CONCLUSION: There is no single ideal treatment for the obliteration of DAVMs. The management of each case is best considered individually. The results of this review serve as a rational starting point for the selection of treatment options.

Adolescent↗
PubMed1997

Surgical resection of intramedullary spinal cord cavernous malformations: delayed complications, long-term outcomes, and association with cryptic venous malformations.

OBJECTIVE: To examine outcomes and delayed complications after the surgical resection of intramedullary spinal cord (IMSC) cavernous malformations. The association of these lesions with cryptic intraparenchymal venous malformations at surgery also was analyzed. METHODS: The records of 17 patients who underwent resection of their histologically verified IMSC cavernous malformations were analyzed. There were nine female and eight male patients (mean age, 40.1 yr). The locations of the cavernous malformations were as follows: cervical, eight; thoracic, eight; and conus medullaris, one. The mean follow-up period was 48.3 months. Immediate postoperative and long-term neurological outcomes were compared, and delayed complications were assessed. RESULTS: The patients presented with radiculopathy (n = 6), myelopathy (n = 10), and conus medullaris syndrome (n = 1). Intraoperatively, 16 (94.1%) IMSC cavernous malformations were associated with cryptic venous malformations. Immediately after surgery, four (23.5%) patients worsened neurologically whereas one (5.9%) improved. At long-term follow-up, however, 10 (58.9%) patients had improved and only 1 (5.9%) remained worse. Four (23.5%) patients experienced delayed complications. Three had undergone incomplete resection and experienced subsequent hemorrhage, necessitating subsequent resection. Another patient developed radiological tethering of the thoracic spinal cord without clinical symptoms. Two of the three patients who had undergone subsequent resection developed symptomatic tethering of the cervical spinal cord. In one of the two patients, the tethering was associated with an iatrogenic cerebellar tonsillar herniation. Both patients required surgical intervention. CONCLUSIONS: The frequent coexistence of IMSC cavernous malformations with cryptic venous malformations in this series indicates a need for operative vigilance to preserve these venous anomalies. Delayed complications were the result of incomplete resection. The resultant hemorrhage required reexploration, which led to tethering of the spinal cord. Most patients who underwent resection, however, had improved neurologically at long-term follow-up.

Adolescent↗