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Biomedical subjects

B Gregory Thompson

Publications and source records attributed to B Gregory Thompson.

At least 19 recordsLinked to original sources
PubMed2006

Hearing preservation and facial nerve outcomes in vestibular schwannoma surgery: results using the middle cranial fossa approach.

OBJECTIVE: To evaluate surgical results using the middle cranial fossa approach for hearing preservation vestibular schwannoma surgery. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral academic center. PATIENTS: Seventy-three consecutive patients with vestibular schwannoma operated on using the middle cranial fossa approach between February 1999 and February 2005. INTERVENTIONS: The tumors were removed via the middle cranial fossa approach with modifications to improve exposure. Standard auditory brainstem and facial nerve monitoring were used. MAIN OUTCOME MEASURES: Pre- and postoperative hearing measures and facial function, tumor size, and postoperative complications. Hearing status was categorized into Classes A, B, C, and D as described by the American Academy of Otolaryngology-Head and Heck Surgery "Guidelines for the Evaluation of Hearing Preservation in Acoustic Neuroma, 1995." RESULTS: Thirty-four patients presented with Class A hearing preoperatively. Among patients presenting with Class A hearing, a total of 27 (80%) maintained Class A or B hearing postoperatively. Of these, 21 (62%) remained in Class A, 6 (18%) deteriorated slightly to Class B, and 7 (20%) deteriorated to Class D postoperatively. Twenty-eight patients presented with Class B hearing preoperatively. Of these, 18 (64%) remained in Class B, 3 (11%) deteriorated to Class C, and 7 (25%) deteriorated to Class D. Three patients had Class C hearing preoperatively. Of these, 2 (66%) remained in Class C and 1 (33%) deteriorated to Class D. Eight patients presented in Class D and one of these improved to Class C postoperatively. Overall, 62 patients presented with useful (Class A or B) hearing and 45 (73%) remained in Class A or B. Nineteen patients had tumors larger than 10 mm in greatest dimension and had Class A or B hearing preoperatively. Of these, 11 (58%) retained Class A or B hearing postoperatively. At 4 months or greater follow-up, facial nerve outcome were excellent in 96%: House-Brackmann Grade I in 61 (85%), Grade II in 8 (11%), and Grade III in 3 (4%). There were no Grade IV, V, or VI results on final follow-up. Six (8%) patients developed cerebrospinal fluid leaks. CONCLUSION: By achieving excellent exposure and using meticulous microsurgical technique, it is possible to resect small vestibular schwannomas via the middle fossa approach, with preservation of hearing at excellent or preoperative levels in the majority of patients, with excellent or satisfactory facial nerve outcomes in 96% of patients.

Audiometry, Evoked Response↗
PubMed2005

Surgical reversal of prolonged blindness from a metastatic neuroblastoma.

BACKGROUND: Reports of tumor-related anterior visual pathway blindness that have resolved after surgical decompression are rare. The longest reported duration of tumor-related blindness completely reversed by optic nerve decompression is 3 days. We describe a pediatric patient with 7 days of no light perception who experienced reversal of blindness following tumor resection and optic nerve decompression. CASE DESCRIPTION: A 33-month-old boy presented with a 4-day history of no light perception. Magnetic resonance imaging revealed a mass involving the sphenoid sinus, sella turcica, and clivus with significant optic nerve involvement. Loss of light perception and complete absence of a pupillary light reflex were documented for the next 72 h. A sluggish pupillary light reflex was regained 24 h after instituting intravenous steroids. An urgent bi-frontal craniotomy and optic nerve decompression were performed 7 days after the onset of blindness. Surgical pathology revealed metastatic neuroblastoma. Eleven days after optic nerve decompression, the child was able to count fingers and recognize faces and printed book characters. CONCLUSION: Prolonged blindness secondary to tumor-related optic nerve compression may be reversible up to 1 week from onset in children presenting with no light perception.

Blindness↗
PubMed2005

The falcine trigeminocardiac reflex: case report and review of the literature.

BACKGROUND: Trigeminocardiac reflex (TCR), the reproducible hypotension and bradycardia upon stimulation of the trigeminal nerve, has been reported during craniofacial surgery and during surgery within the cerebellopontine angle, petrosal sinus, orbit, and trigeminal ganglion. Whereas the falx cerebri is known to be innervated by the nervus tentorii, a recurrent branch of V1, there have been no reports to date of this response upon mechanical stimulation of the falx. CASE DESCRIPTION: We report a case of immediate, reproducible, and reflexive response of asystole upon stimulation of the falx cerebri during operative resection of a parafalcine meningioma in a 53-year-old woman. Upon recognition of the reproducible relationship between falcine stimulation and increased vagal tone, the patient was given glycopyrrolate in an effort to block cholinergic hyperactivity. After glycopyrrolate was given, no further dysrhythmias occurred. CONCLUSION: In this patient, mechanical stimulation of the falx likely resulted in the hyperactivity of the trigeminal ganglion, thereby triggering TCR. The dorsal region of the spinal trigeminal tract includes neurons from hypoglossal and vagus nerves, and projections have been seen between the vagus and trigeminal nuclei. The vagus provides parasympathetic innervation to the heart, vascular smooth muscle, and abdominal viscera. Vagal stimulation via these connections after trigeminal nerve activation likely accounts for the reflexive response of asystole seen in this patient. This is confirmed by the observation that the reflex was inhibited by the anticholinergic effects of glycopyrrolate. Awareness of TCR allows for early detection and appropriate treatment.

Blood Pressure↗
PubMed2005

Ocular ischemic syndrome after occlusion of both external carotid arteries.

The ocular ischemic syndrome (OIS) has been reported in association with high-grade stenosis or occlusion of the common carotid artery (CCA) or internal carotid artery (ICA) but never with high-grade stenosis or occlusion of the external carotid artery (ECA) alone. We describe two patients who developed OIS with bilateral occlusion of the ECAs yet patent CCAs and ICAs. In one case, unilateral OIS followed consecutive bilateral carotid endarterectomies. In the other case, OIS developed spontaneously OU but was exacerbated in one eye after ipsilateral carotid endarterectomy (CE) in the setting of pre-existing contralateral ECA occlusion. In some individuals, the ECA is the primary source of arterial blood flow to the eye. Because of this fact, the endarterectomy surgeon must avoid causing ECA occlusion by meticulously removing not only the ICA plaque, but also the entire ECA plaque.

Aged↗
PubMed2005

Propionibacterium infection associated with bovine pericardium dural allograft. Case report.

Propionibacteria are known to play a part in postneurosurgical infections, primarily those involving ventricular shunts. Nevertheless, little is known about the association between dural allografts and propionibacterium infections. Two patients underwent craniotomy for supratentorial meningiomas and each received a dural allograft. Both patients subsequently presented with delayed epidural fluid collections several weeks after surgery. Propionibacterium species was cultured in samples from both patients. The allografts were removed and the patients were treated with appropriate antibiotic agents; one patient underwent an interval craniectomy. Both patients demonstrated neuroimaging and clinical improvement after surgery and antiobiotic therapy. These cases demonstrate the association of propionibacterium infections with dural allografts. Furthermore, in patients with latent and indolent infections, Propionibacterium spp. should be suspected and treated appropriately.

Aged↗
PubMed2004

Cerebral perfusion CT: technique and clinical applications.

Perfusion computed tomography (CT) is a relatively new technique that allows rapid qualitative and quantitative evaluation of cerebral perfusion by generating maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT). The technique is based on the central volume principle (CBF = CBV/MTT) and requires the use of commercially available software employing complex deconvolution algorithms to produce the perfusion maps. Some controversies exist regarding this technique, including which artery to use as input vessel, the accuracy of quantitative results, and the reproducibility of results. Despite these controversies, perfusion CT has been found to be useful for noninvasive diagnosis of cerebral ischemia and infarction and for evaluation of vasospasm after subarachnoid hemorrhage. Perfusion CT has also been used for assessment of cerebrovascular reserve by using acetazolamide challenge in patients with intracranial vascular stenoses who are potential candidates for bypass surgery or neuroendovascular treatment, for the evaluation of patients undergoing temporary balloon occlusion to assess collateral flow and cerebrovascular reserve, and for the assessment of microvascular permeability in patients with intracranial neoplasms. This article is a review of the technique, clinical applications, and controversies surrounding perfusion CT.

Blood Volume↗
PubMed2004

Carotid perfusion CT with balloon occlusion and acetazolamide challenge test: feasibility.

Carotid balloon test occlusion (BTO) is used to assess the collateral circulation and cerebrovascular reserve in patients in whom carotid artery occlusion is contemplated. Eight patients in whom the test was successful were evaluated with perfusion computed tomography (CT) in the resting state and after acetazolamide challenge. Three of the patients showed symmetric blood flow and normal response to acetazolamide. One of them underwent permanent carotid occlusion and did not develop any delayed ischemic stroke. The remaining five patients showed asymmetric blood flow. One of them had markedly low blood flow and abnormal response to acetazolamide. The patient developed ipsilateral hemispheric stroke following permanent carotid occlusion after the superficial temporal artery to middle cerebral artery bypass graft occluded. In the other four patients, the steal phenomenon was seen in ipsilateral and contralateral hemispheres. Although definitive quantitative values for perfusion CT are not yet standardized, it may be feasible to predict that the patients with symmetric blood flow and normal acetazolamide-enhanced challenge test results will do well after permanent carotid occlusion. Patients with asymmetric blood flow and abnormal response to the acetazolamide challenge test may require a revascularization procedure to protect them from delayed ischemic stroke.

Acetazolamide↗
PubMed2004

Risk of infection with prolonged ventricular catheterization.

OBJECTIVE: The relationship between extended ventricular catheterization and infection remains controversial. Although studies have substantiated an increasing infection rate with prolonged catheterization, there has been less agreement on whether this trend continues beyond 10 days. Our study reviews the daily infection rate of 595 patients, 213 of whom underwent more than 10 days of catheterization. METHODS: All patients who underwent ventricular monitoring in the neurological intensive care unit from 1995 to 2003 at the University of Michigan Health System were reviewed retrospectively. Infection was defined as a positive cerebrospinal fluid culture. Life-table analysis was used to calculate daily hazard (infection) rates. Patient age, sex, diagnosis, catheter exchanges, location of patient during catheter insertion, and cerebrospinal fluid leak were evaluated as risk factors for infection. RESULTS: The average patient age was 51.3 years, and 51.3% were male. Duration of catheterization averaged 8.6 days. The overall infection rate was 8.6%. Daily infection rates increased from the onset of catheter insertion but reached a plateau after Day 4, with subsequent rates ranging predominantly between 1 and 2%, even with extended catheterization beyond 10 days. Only ventricular catheters that had been placed at other institutions significantly affected the infection rate. CONCLUSION: A relationship between duration of catheterization and infection seems to be present. However, this relationship is not linear. There is an extremely low daily infection rate that rises over the initial 4 days but then remains relatively constant even with prolonged catheter use. Clinical decisions to continue ventricular catheterization should reflect this low daily risk of infection, which does not seem to increase with extended catheter use.

Adolescent↗
PubMed2004

Intravenously administered abciximab in the management of early cerebral ischemia after carotid endarterectomy: case report.

OBJECTIVE AND IMPORTANCE: Cerebral ischemia is the most worrisome perioperative complication of carotid endarterectomy (CEA). The stroke rate occurring with CEA is estimated to range from 2.3 to 6.3%. Numerous treatment options are available to the neurosurgeon in this scenario, although no "gold standard" exists. CLINICAL PRESENTATION: A 61-year-old woman presented with acute left arm weakness 40 minutes after an uneventful CEA for symptomatic carotid stenosis. Emergent angiography demonstrated vascular irregularities in a "moth-eaten" pattern along the arteriotomy closure, suggestive of platelet-fibrin aggregates ("white clot"). INTERVENTION: Abciximab was immediately administered intravenously in the angiography suite, with subsequent improvement of the visualized vascular irregularities on a second angiogram performed 12 minutes after infusion and complete resolution of the presumed platelet-fibrin aggregates on a third angiogram performed the next day. The patient had no further episodes of cerebral ischemia. She was discharged home on the fifth postoperative day with improving left arm weakness, which had completely resolved by her 2-month follow-up visit. CONCLUSION: To our knowledge, this is the first reported case of abciximab administered intravenously in the setting of acute thromboembolic brain ischemia after CEA. For the unique situation in which an acute thrombus, or white clot, is thought to be the cause of cerebral ischemia, we believe that abciximab may offer an effective and potentially safer alternative than fibrinolytics and may be a more appropriate drug to use from a physiological perspective.

Abciximab↗
PubMed2004

Transient magnetic resonance imaging signal alterations in the brainstem after microvascular decompression for trigeminal neuralgia: case report.

OBJECTIVE AND IMPORTANCE: We present a case of transient signal alterations along the brainstem path of the trigeminal nerve after microvascular decompression in a patient with trigeminal neuralgia. Such signal changes have been previously reported to represent infarction, but in our patient, they seemed to represent reactive neural and nuclear changes attributable to operative manipulation. CLINICAL PRESENTATION: A 43-year-old woman presented with gradually increasing, medically refractory recurrent trigeminal neuralgia 16 months after initial successful microvascular decompression for trigeminal neuralgia. Repeat microvascular decompression resulted initially in complete pain relief; however, her pain suddenly returned on the 3rd postoperative day. Magnetic resonance imaging (MRI) of this recurrent pain revealed new signal alterations along the brainstem path of the trigeminal nerve. Other than marked reduction in her trigeminal neuralgia, the patient had no postoperative alterations of trigeminal sensory or motor function. INTERVENTION: The patient's residual postoperative trigeminal neuralgia was successfully treated with carbamazepine. Because of the absence of worrisome signs and symptoms corresponding to the MRI signal alterations, no additional therapy was elected. Follow-up MRI in 1 month revealed near-complete resolution of the postoperative signal alterations along the brainstem path of the trigeminal nerve. CONCLUSION: MRI signal alterations along the brainstem path of the trigeminal nerve after microvascular decompression may be only reactive and do not always represent infarction. Depending on the clinical picture, observation may be all that is necessary in such cases.

Adult↗
PubMed2004

Intracerebral hemorrhage: pathophysiology and therapy.

Spontaneous intracerebral hemorrhage, from several sources, causes instantaneous mass effect, disruption of surrounding brain, and often an early neurological death. If the patient survives the initial event, the hematoma can lead to secondary brain injury, neurological deficits, and, occasionally, delayed fatality. The mechanisms that trigger pathophysiological changes in and around the hematoma are becoming better understood, offering new therapeutic opportunities.

Blood Coagulation↗
PubMed2004

Progression of a posterior communicating artery infundibulum into an aneurysm in a patient with Alagille syndrome. Case report.

The authors present a case in which a posterior communicating artery (PCoA) infundibulum progressed into an aneurysm in a patient with Alagille syndrome (arteriohepatic dysplasia). The 3-mm PCoA infundibulum had been noted on angiography studies obtained 5 years earlier, prior to clip occlusion of a basilar tip aneurysm. Recently, the patient presented to the emergency department with the sudden onset of headache and decreased mental status. A computerized tomography scan of the head with three-dimensional angiography revealed no gross subarachnoid hemorrhage, but did demonstrate a 5-mm PCoA aneurysm. Lumbar puncture demonstrated xanthochromia and a large quantity of red blood cells. The patient underwent open surgery for aneurysm clip occlusion and obtained a good recovery. This case illustrates the small but growing number of examples of infundibulum progression. It also indicates the need for a close follow up in patients with congenital abnormalities that may pose an increased risk for what has traditionally been considered a benign lesion.

Adult↗
PubMed2003

Spontaneous intracerebral hemorrhage: a review.

Spontaneous intracerebral hemorrhage (SICH) is a blood clot that arises in the brain parenchyma in the absence of trauma or surgery. This entity accounts for 10 to 15% of all strokes and is associated with a higher mortality rate than either ischemic stroke or subarachnoid hemorrhage. Common causes include hypertension, amyloid angiopathy, coagulopathy, vascular anomalies, tumors, and various drugs. Hypertension, however, remains the single greatest modifiable risk factor for SICH. Computerized tomography scanning is the initial diagnostic modality of choice in SICH, and angiography should be considered in all cases except those involving older patients with preexisting hypertension in thalamic, putaminal, or cerebellar hemorrhage. Medical management includes venous thrombosis prophylaxis, gastric cytoprotection, and aggressive rehabilitation. Anticonvulsant agents should be prescribed in supratentorial SICH, whereas the management of hypertension is controversial. To date, nine prospective randomized controlled studies have been conducted to compare surgical and medical management of SICH. Although definitive evidence favoring surgical intervention is lacking, there is good theoretical rationale for early surgical intervention. Surgery should be considered in patients with moderate to large lobar or basal ganglia hemorrhages and those suffering progressive neurological deterioration. Elderly patients in whom the Glasgow Coma Scale score is less than 5, those with brainstem hemorrhages, and those with small hemorrhages do not typically benefit from surgery. Patients with cerebellar hemorrhages larger than 3 cm, those with brainstem compression and hydrocephalus, or those exhibiting neurological deterioration should undergo surgical evacuation of the clot. It is hoped that the forthcoming results of the International Surgical Trial in IntraCerebral Hemorrhage will help formulate evidence-based recommendations regarding the role of surgery in SICH.

Adult↗
PubMed2003

The impact of provider volume on mortality after intracranial tumor resection.

OBJECTIVE: Policies of regionalization and selective referral for a number of "high-risk" surgical procedures are being explored and implemented as a result of significant variation in postoperative mortality between high- and low-volume providers. The effect of provider volume on outcomes after intracranial tumor resection is unknown and warrants investigation. METHODS: By use of the Nationwide Inpatient Sample for 1996 and 1997, patients (older than 19 yr) who had a diagnosis of a malignant central nervous system neoplasm and underwent craniotomy or craniectomy were included. Hospital volume and surgeon volume were categorized by quartiles (very low, low, high, or very high volume). Unadjusted and case mix-adjusted analyses were performed with regard to postoperative in-hospital mortality. RESULTS: The crude in-hospital mortality was 2.8% for a total of 7547 patients. The mean patient age was 55.8 years (66.5% <65; 33.5% >/=65). Mortality for very low- to very high-volume hospitals was as follows: 3.8, 3.2, 2.4, and 1.8% (P < 0.001). Mortality for very low- to very high-volume surgeons was as follows: 4.1, 3.9, 3.1, and 1.4% (P = 0.003). Predictors of mortality in a logistic regression model were emergent admission (odds ratio [OR], 2.97; 95% confidence interval [CI], 2.02-4.38; P < 0.001), and age 65 years or greater (OR, 1.63; 95% CI, 1.16-2.30; P = 0.005). The risk of mortality was reduced for very high-volume hospitals (OR, 0.58; 95% CI, 0.35-0.97; P = 0.038) and very high-volume surgeons (OR, 0.42; 95% CI, 0.22-0.84; P = 0.012). CONCLUSION: Higher-volume providers have superior outcomes after surgical resection of malignant intracranial tumors. This reduction was maintained despite adjustment for case mix. As the regionalization of high-risk surgery moves forward, it is important for neurosurgeons to maintain leadership roles in the development of specialty-specific data collection and health policy initiatives that improve and reduce variation in outcomes.

Adult↗
PubMed2003

Recombinant activated factor VII for the rapid correction of coagulopathy in nonhemophilic neurosurgical patients.

OBJECTIVE: Coagulopathy is a significant contraindication for neurosurgery. Unfortunately, many coagulopathic patients require urgent neurosurgical intervention. Standard use of blood products, including fresh-frozen plasma or prothrombin complexes, to correct the coagulopathy often leads to significant delays in treatment. Recombinant activated factor VII (rFVIIa) is a medication originally designed to treat bleeding in hemophiliacs but also seems to correct a wide variety of coagulopathies rapidly and safely in nonhemophilic patients. METHODS: The medical records of nine patients with coagulopathy requiring urgent neurosurgical intervention were reviewed retrospectively. Each patient was given a dose ranging from 40 to 90 microg/kg of rFVIIa before undergoing surgery. Pre-rFVIIa coagulation and post-rFVIIa coagulation parameters were obtained. Once correction of the coagulopathy was verified, each patient underwent the appropriate neurosurgical procedure. RESULTS: The average age of the patients was 40.9 years; six were women. The causes of the coagulopathy included anticoagulant medication, liver dysfunction, and dilutional coagulopathy after traumatic hemorrhage. Neurosurgical indications included intraparenchymal/intraventricular hemorrhage, hydrocephalus, diffuse cerebral edema, and epidural hematoma. Post-rFVIIa coagulation parameters obtained as early as 20 minutes after infusion of the medication showed normalization of values. There were no procedural or operative complications and no postoperative hemorrhagic complications. No associated thromboembolic or other complications with the use of rFVIIa were observed. CONCLUSION: The use of rFVIIa for the urgent surgical treatment of coagulopathic patients is quite promising. Further studies, including randomized, prospective trials using rFVIIa to address issues such as optimal dosing, efficacy, surgical indications, cost-effectiveness, morbidity, and mortality are needed.

Adolescent↗
PubMed2003

Outcomes after cerebral aneurysm clip occlusion in the United States: the need for evidence-based hospital referral.

OBJECT: In an age of multimodality and multidisciplinary treatment of cerebral aneurysms, patient outcomes have improved significantly. For a number of complex surgical procedures, hospitals with high case volumes yield superior outcomes. The effect of hospital volume on the mortality rate after emergency and elective cerebral aneurysm clip occlusion in a nationally representative sample of patients is unknown. METHODS: Using clinical data derived from the Nationwide Inpatient Sample for the years from 1995 through 1999, 12,023 patients who underwent clip occlusion of a cerebral aneurysm (International Classification of Diseases, Ninth Revision, Clinical Modification code 3951) were included. Patient age, comorbid conditions, nature of admission, and diagnosis of subarachnoid hemorrhage were abstracted. Hospital case volume was grouped into quartiles. Unadjusted and case-mix adjusted analyses were performed. The mean patient age was 53.2 +/- 13.5 years. The overall crude postoperative mortality rates for emergency and elective aneurysm clip occlusion were 12.2 and 6.6%, respectively. Very low volume hospitals demonstrated higher mortality rates than very high volume hospitals for both emergency (14.7 compared with 8.9%, p < 0.001) and elective (9.4 compared with 4.5%, p < 0.001) aneurysm surgery. Patient-specific predictors of death in the multivariate model were renal disease (odds ratio [OR] 3.32, p < 0.042); age (> 60 years, OR 2.36, p < 0.001; 51-60 years, OR 1.63, p < 0.001; 40-50 years, OR 1.25, p = 0.047); chronic obstructive pulmonary disease (present, OR 1.52, p < 0.001); and nature of admission (emergency, OR 1.18, p = 0.03). Provider-specific predictors of death included very low volume (OR 1.59, p < 0.001); low-volume (OR 1.37, p = 0.001); and high-volume (OR 1.45, p < 0.001) hospitals compared with very high volume hospitals. CONCLUSIONS: A significant volume-outcome effect exists for surgical treatment of cerebral aneurysms in the US. Factors influencing this effect should be investigated to guide future healthcare policy and evidence-based referral. Whenever possible, healthcare practitioners should refer patients to centers in which superior outcomes are consistently demonstrated.

Adult↗