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Biomedical subjects

W T Couldwell

Publications and source records attributed to W T Couldwell.

At least 55 records · Page 3Linked to original sources
PubMed1998

Cerebellar contusion associated with type I Chiari malformation following supratentorial head trauma: case report.

Acute presentation of Type I Chiari malformation in children is distinctly rare. An 11 year old male suffered a trauma to the right temporal-parietal region in a tobogganing accident resulting in an open depressed skull fracture. Radiographic evaluation included a Computed Tomographic scan which also demonstrated a significant cerebellar contusion and the presence of subarachnoid hemorrhage in the region of craniovertebral junction. Magnetic Resonance imaging revealed an underlying Type I Chiari malformation. Somatosensory evoked responses shortly following the injury demonstrated slowing of conduction across the lower brainstem. The open depressed fracture was debrided and elevated. Subsequent observation resulted in slow improvement in neurological function. A followup somatosensory evoked potential study performed 21 days following the accident showed improvement in conduction across the craniovertebral junction. The tonsillar ectopia associated with Type I Chiari malformation may predispose to cerebellar, upper spinal and brainstem injury following supratentorial trauma.

Arnold-Chiari Malformation↗
PubMed1998

Pediatric intracranial epidural abscess secondary to an infected scalp vein catheter.

The authors present a case of a 5-week-old infant developing a retrotorcular epidural abscess as a result of an infected scalp vein catheter. The abscess developed in the absence of sinusitis, otitis, trauma, or prior surgery. The diagnosis of epidural abscess was made on the basis of magnetic resonance imaging and ultrasound-guided aspiration of the fluid collection. An identified strain of Staphylococcus epidermidis was cultured from both the intravenous catheter and the abscess. The patient underwent a suboccipital craniectomy with drainage of the abscess and a 6-week total course of intravenous antibiotics. Magnetic resonance imaging 4 months after the procedure and 2.5-year pediatric clinic follow-up have demonstrated no evidence of neurologic deficit or recurrence. When present, a scalp vein catheter must be considered as an etiologic agent for an intracranial epidural abscess in this age-group.

Brain Abscess↗
PubMed1998

Experience in the surgical management of 82 symptomatic herniated thoracic discs and review of the literature.

OBJECT: The authors aimed to develop management strategies for the treatment of herniated thoracic discs and to define indications for selection of surgical approaches. Symptomatic thoracic discs requiring surgery are rare. Between 1971 and 1995, 71 patients with 82 herniated thoracic discs were surgically treated by the authors. The treated group included 34 men and 37 women whose ages ranged from 19 to 75 years, with a mean age of 48 years. The most common sites of disc herniation requiring surgery were from T-8 to T-11. Evidence of antecedent trauma was present in 37% of the patients. Preoperative symptoms included pain (localized, axial, or radicular) in 54 (76%) of the 71 patients, evidence of myelopathy, that is, motor impairment in 43 (61%), hyperreflexia and spasticity in 41 (58%), sensory impairment in 43 (61%), and bladder dysfunction in 17 (24%). METHODS: Radiological diagnosis for the patients in this series was accomplished by means of myelography, computerized tomography myelography, or magnetic resonance imaging. Classification of the disc location into two groups reveals that 94% were centrolateral and 6% were lateral. Evidence of calcification was present in 65% of patients, and in 7% intradural extension was noted at surgery. Ten patients (14%) were found to have multiple herniations. Four surgical approaches were used for the removal of these 82 disc herniations: transthoracic in 49 (60%), transfacet pedicle-sparing in 23 (28%), lateral extracavitary in eight (10%), and transpedicular in two (2%). Postoperative evaluation revealed improvement or resolution of pain in 47 (87%) of 54, hyperreflexia and spasticity in 39 (95%) of 41, sensory changes in 36 (84%) of 43, bowel/bladder dysfunction in 13 (76%) of 17, and motor impairment in 25 (58%) of 43. Complications occurred in a total of 12 (14.6%) of 82 discs treated surgically. Major complications were seen in three patients and included perioperative death from cardiopulmonary compromise, instability requiring further surgery, and an increase in the severity of a preoperative paraparesis. CONCLUSIONS: Review of this series, with the attendant complications, together with evaluation of several contemporary thoracic disc series, has facilitated the authors' decision-making process when considering the comprehensive management of these patients, including the selection of a surgical approach.

Adult↗
PubMed1998

Irving S. Cooper (1922-1985): a pioneer in functional neurosurgery.

Irving S. Cooper (1922-1985), the son of a salesman, worked his way through high school, college, and medical school to become one of the pioneers in functional neurosurgery. He developed several novel techniques for the surgical management of Parkinson's disease and other crippling movement disorders. A keen interest in the physiology of movement disorders was kindled by his doctoral research and continued during his neurosurgical training. He began to apply this knowledge to surgical practice in 1952 when he began his faculty career as Assistant Professor of Surgery at New York University. At the time, surgical treatment of parkinsonian tremor focused on various techniques used to interrupt the pyramidal tract. During a subtemporal approach for a cerebral pedunculotomy, he inadvertently injured and, subsequently, was forced to occlude the anterior choroidal artery. Much to Cooper's surprise, following emergence from anesthesia the patient's tremor and rigidity were abolished without any residual hemiparesis. This serendipitous observation, together with Meyer's earlier work on the role of the basal ganglia in motor control, helped focus surgical efforts on targets within the basal ganglia and, subsequently, within the thalamus to alleviate the movement disorders associated with Parkinson's disease. While at New York University, Cooper developed chemopallidectomy and, later at St. Barnabas Hospital in the Bronx (1954-1977), he used cryothalamectomy as a surgical technique for primary control of tremor in patients with Parkinson's disease. Cooper authored many original papers on surgical techniques and several textbooks on the lives of patients afflicted with Parkinson's disease and other crippling movement disorders. Although considered controversial, this fascinating and complex neurosurgeon made significant contributions to this field.

Cryosurgery↗
PubMed1997

Inhibition of human malignant glioma cell motility and invasion in vitro by hypericin, a potent protein kinase C inhibitor.

The effect of hypericin, an antiviral drug and a potent protein kinase C (PKC) inhibitor, on glioma cell invasion was investigated in vitro. Treatment of the established human glioblastoma cell line, T98G, with 1 microM hypericin for 24 h resulted in a significant inhibition of the cell invasion through an artificial basement membrane, but not cell attachment or proliferation. Furthermore, tamoxifen and staurosporine, both PKC inhibitors, also inhibited T98G cell invasion, suggesting that PKC may be the cellular target for hypericin-inhibited glioma cell migration. Similarly, hypericin decreased cell motility significantly in established lines, T98G and U87-MG, and also in a low-passage human malignant glioma cell line. Thus, hypericin may prove useful for studying mechanisms of glioma invasion, and may represent a new agent in malignant glioma therapy.

Anthracenes↗
PubMed1997

Prognostic variables in surgery for skull base meningiomas.

The authors have retrospectively analyzed selected surgical and pathological observations made among a group of 20 patients harboring recurrent cranial base meningiomas in an attempt to reveal which factors may be important in predicting tumor recurrence. This cohort was compared with a group of 34 patients with cranial base meningiomas that underwent primary resection and in whom tumor recurrence has not been demonstrated over a median follow-up period of 33 months. Features analyzed included brain, cranial nerve, carotid artery, or muscle invasion as well as tumor cellularity, nucleolar prominence, cellular pleomorphism, and percentage of cells staining positive for the Ki-67 antigen. As expected, increased cellularity and tumor necrosis were relatively more prevalent in recurrent tumors. With regard to tumor type, atypical and anaplastic tumors were more common in the group of patients with recurrent tumor compared with the primary group (p < 0.02). As expected, increased cellularity was relatively more prominent in recurrent tumors. Invasion of muscle and bone (72%) was more frequently associated with recurrent tumors, suggesting that these characteristics may be important features of recurrent skull base meningiomas.

Journal Article↗
PubMed1997

Osteosarcoma of the meninges in association with glioblastoma.

Primary intracranial osteosarcoma not originating in the skull is a distinctly rare tumour, as is post-irradiation sarcoma of short latency. The authors report the case of a 56 year old caucasian male who underwent resection of a glioblastoma of the left temporal region and was subsequently administered partial field external beam radiation therapy (XRT) to a total dose of 5940 cGy. Seven months following the completion of XRT, an enhancing region adjacent to the surgical site was noted on followup magnetic resonance images (MRI), one which increased in size on serial studies. Initial biopsy of the dural lesion adjacent to the temporal resection site revealed a sarcoma with a suggestion of osseous differentiation. Subsequent reoperation with resection of the lesion showed it to be a primary meningeal tumour, and histological evaluation of the lesion demonstrated an osteosarcoma. Immunohistochemical staining for p53 protein performed on both the original glioblastoma and the subsequently resected osteosarcoma showed widespread nuclear positivity. The clinical, radiographic and pathologic features of this unusual case are discussed. Meningeal osteosarcoma should be included among the rare secondary sarcomas of the meninges which may be associated with malignant glioma.

Bone Neoplasms↗
PubMed1997

Prolonged treatment with biologic agents for malignant glioma: a case study with high dose tamoxifen.

Traditional study design for treatment of malignant gliomas does not allow tumor progression to be greater than 25-50 percent without terminating treatment. This design may prevent recognition of patients who benefit from the treatment either by slowed growth or delayed response. A delayed response or slowed growth may be characteristic of biologic agents being evaluated in the treatment of malignant glioma. Because of the low toxicity of certain biologic drugs, continued treatment through tumor growth can be ethically considered in study design. The effect of biologic agents on a neoplasm may include cellular differentiation, retardation of growth, cytostasis, cytocidal effects, or apoptosis. Such effects may clinically translate into a complete response, partial response, stable disease or retardation of growth with or without an eventual reduction of tumor. We present a patient with a recurrent malignant glioma who was continued on high dose tamoxifen despite radiologic documented doubling of the tumor size and who eventually showed a delayed response to this agent nine months after initiation of treatment. Strong consideration should be given to the prolonged treatment of non-toxic biologic agents in a controlled clinical trial, where agents have shown some benefit in phase one studies.

Adult↗
PubMed1997

Reconstruction of the skull base and cranium adjacent to sinuses with porous polyethylene implant: preliminary report.

Surgical reconstruction of the skull base and cranium adjacent to open paranasal sinuses with alloplastic materials is problematic secondary to an increased risk of implant infection in these locations. The authors report their initial experience with the use of a porous polyethylene implant for closure of defects in these locations in 20 patients, in 14 of these with the implant placed in direct contact with the mastoid or paranasal simuses. The implant is flexible, which facilitates surgical reconstruction of the cranial base, and porous in nature, which enhances soft tissue and bone ingrowth in decrease the risk of infection. The implant is radiolucent on plain roentgenograms and CT, and produces no imaging artifact on MRI. The implant was utilized for a variety of skull base of cranium adjacent to sinus reconstructive applications with no infectious complications, with a follow-up period ranging from 8 to 50 months. This preliminary experience suggests that the alloplast may be a useful adjunct in skull base reconstruction, and further evaluation of its use in this application is warranted.

Journal Article↗
PubMed1997

Transmaxillary approach to the anterior cavernous sinus: a microanatomic study.

OBJECTIVE: Several approaches to expose the anterior cavernous sinus have been used, such as frontotemporal, orbitofrontal, anterior subtemporal, and various transfacial approaches. In an effort to gain exposure to the anterior cavernous sinus without necessitating a craniotomy or wide transfacial exposure, the authors in the present study have developed a transmaxillary approach to the cavernous sinus. METHODS: The approach was developed using data obtained by performing 24 cadaveric dissections. Using a sublabial incision to expose the maxilla, maxillotomy is performed and the course of the infraorbital nerve is identified as a guide to the maxillary branch of the trigeminal nerve. After an osteotomy of the posterior sinus wall and pterygoid plate, the foramen rotundum is identified, which lies a mean of 10 mm from the posterior wall of the maxilla. A superomedial enlargement of the foramen rotundum is then undertaken to ultimately expose the anterior cavernous sinus. RESULTS: This technique offers access to all cavernous cranial nerves, as well as the entire course of the anterior loop of the internal carotid artery to the origin of the ophthalmic artery. With a mean operative range of 38 mm from the posterior wall of the maxilla to the anterior loop of the internal carotid artery, this approach offers adequate exposure with a short operative distance. CONCLUSION: The approach may be useful in limited exposure of tumors of the anterior cavernous sinus and some intracavernous vascular lesions.

Brain Mapping↗
PubMed1996

Protein kinase C and growth regulation of pituitary adenomas.

The present study was undertaken to explore the role of the Protein Kinase C (PKC) signal transduction system in growth regulation of pituitary adenomas. Primary tumor cultures were plated from fresh surgical tumor specimens. The PKC inhibitors Staurosporine and Tamoxifen were added at varying dosages to the cell cultures. Measurements of cell proliferation were performed by [3H]-thymidine uptake and the [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide] (MTT) assay. After a 48 h treatment period, both [3H]-thymidine uptake and absorbance on the MTT assay decreased in a dose-related manner in both the staurosporine and tamoxifen-treated cultures (IC50 of 10 nM and 30 microM respectively). Direct measurement of PKC activity using an in vitro assay revealed very high activity (range of 1465-5708 pmol/min/mg protein; within the range previously published for malignant glioma specimens) in 12 frozen specimens of pituitary adenomas (9 nonfunctional adenomas, 1 prolactinoma, 1 gonadotrophin-secreting and 1 corticotroph-secreting adenoma). In contrast, PKC activity measured in normal adenohypophysis was comparatively very low. These data indicate that pituitary adenoma cells display high PKC activity and are sensitive to growth inhibition by PKC inhibitors. These data suggest a role for the PKC system in regulating pituitary tumor growth, which may have implications for future therapy of these tumors.

Adenoma↗
PubMed1996

Malignant clival chordoma with postoperative cutaneous metastases.

The authors report the case of a chordoma with malignant cytologic features, presenting as a mass lesion in the clival and infratemporal region at the level of the craniocervical junction in an 8-year-old female. Following gross resection of the mass, the patient subsequently developed distant subcutaneous and peritoneal metastases from the lesion. The rare histologic features, the surgical approach to the lesion, and the follow-up management of this unique case are discussed.

Case Reports↗
PubMed1996

Malignant glioma sensitivity to radiotherapy, high-dose tamoxifen, and hypericin: corroborating clinical response in vitro: case report.

Previous work has demonstrated the importance of protein kinase C in regulating glioma cell proliferation in vitro. Tamoxifen, a protein kinase C inhibitor when administered in high dosages, is currently being used as an adjuvant in the treatment of patients with malignant gliomas. The patient in the present study harbored a left frontal anaplastic astrocytoma adjacent to Broca's area and the paracentral region, which limited gross resection. After a subtotal resection of the tumor and after radiation, the patient was administered high-dose tamoxifen therapy for gross residual gadolinium-enhancing regions that were revealed by magnetic resonance imaging and by high glucose uptake as demonstrated by positron emission tomography. After treatment, a decrease in gadolinium enhancement on magnetic resonance images and a decrease in glucose uptake revealed by positron emission tomography were noted. A laboratory examination of the tissue obtained from the original surgical resection revealed resistance to radiation therapy but sensitivity to tamoxifen as measured by 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide assay. The subsequent in vitro testing of the tumor that was removed after the recurrence of tumor (22 months after the initiation of tamoxifen) revealed loss of sensitivity to tamoxifen. However, the recurrent tumor remained sensitive to growth inhibition by the potent protein kinase C inhibitor, hypericin, despite loss of sensitivity to tamoxifen in vitro, suggesting the potential clinical application of this agent. This close in vitro correlation with the clinical course of the patient in the present study suggests a potential role for such in vitro radiation and chemosensitivity testing in designing a rational individualized clinical course of treatment.

Adult↗
PubMed1996

Vagus nerve stimulation activates central nervous system structures in epileptic patients during PET H2(15)O blood flow imaging.

OBJECTIVE: To determine the central areas of activation by vagal nerve stimulation (VNS) in epilepsy. VNS is a promising neurosurgical method for treating patients with partial and secondary generalized epilepsy. The anti-epileptic mechanism of action from VNS is not well understood. METHODS: We performed H2(15)O PET blood flow functional imaging on three patients with epilepsy in a vagal nerve stimulation study (E04 Protocol with Cyberonics). The three patients included two that had previous epilepsy surgery but continued to have frequent seizures. Seizure onset was frontal in two patients and bitemporal in the third patient. Twelve PET scans per subject were acquired every 10 minutes with a Siemens 953/A scanner. In 6 stimulus scans, VNS was activated for 60 seconds (2 mA, 30 Hz) commensurate with isotope injection. In 6 control scans no VNS was administered. No clinical seizures were present during any scan. Three way ANOVA with linear contrasts subject, task, repetition) of coregistered images identified significant treatment effects. RESULTS: The difference between PET with VNS and without revealed that left VNS activated right thalamus (P < 0.0006), right posterior temporal cortex (P < 0.0003), left putamen (P < 0.0002), and left inferior cerebellum (P < 0.0009). CONCLUSIONS: VNS causes activation of several central areas including contralateral thalamus. Localization to the thalamus suggests a possible mechanism to explain the therapeutic benefit, consistent with the role of the thalamus as a generator and modulator of cerebral activity.

Adult↗
PubMed1996

Neuron-specific enolase is increased after single seizures during inpatient video/EEG monitoring.

Neuron-specific enolase (NSE) is a marker of brain injury after acute neurologic insults. We report changes in serum NSE (s-NSE) in 25 patients (15 with epilepsy and 10 patients with nonepileptic events) during continuous inpatient video/EEG monitoring. s-NSE was significantly increased as compared with baseline and normal controls after the first ictal event in the epileptic group, especially in patients with secondarily generalized tonic-clonic seizures (p = 0.01), but s-NSE was not increased in patients with nonepileptic events. These preliminary data indicate that s-NSE may be increased after complex partial seizures--and generalized tonic-clonic seizures (GTCS).

Adult↗