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Biomedical subjects

L N Sekhar

Publications and source records attributed to L N Sekhar.

At least 19 recordsLinked to original sources
PubMed1992

Combined supratentorial and infratentorial approach to large pineal-region meningioma.

Our case report is used to describe a combined supratentorial and infratentorial approach to a giant pineal-region meningioma. The procedure involves section of the less dominent transverse sinus and the tentorium. After the cerebellum and the occipital lobe are retracted away from each other, the operative procedure is carried out. The brain stem and the large veins of this region are better exposed with minimal retraction of the cerebellum and occipital lobe. The transverse sinus is resutured at the end of the procedure to reestablish the blood circulation. The operative procedure is ideal for extensive lesions in the pineal region, providing wide and direct exposure.

Brain Neoplasms↗
PubMed1992

Chondrosarcomas of the skull base: MR imaging features.

The magnetic resonance (MR) images from 17 patients with chondrosarcomas of the skull base were retrospectively reviewed to characterize the size, location, signal intensity, and extension of these tumors. Eleven patients with chondrosarcomas received intravenously administered gadopentetate dimeglumine. In 16 patients, computed tomographic (CT) scans were obtained to evaluate intratumorous mineralization and bone erosion. On short repetition time (TR)/echo time (TE) MR images, chondrosarcomas generally had low to intermediate signal intensity; on long TR/TE MR images, they generally had very high signal intensity. Signal heterogeneity on long TR/TE MR images was seen in 10 of 17 tumors (59%) and was caused by matrix mineralization, fibrocartilaginous elements, or both. Matrix mineralization was demonstrated with CT in seven of the 16 chondrosarcomas. Chondrosarcomas showed marked enhancement after administration of gadopentetate dimeglumine in either a heterogeneous (n = 8) or homogeneous (n = 3) pattern. The information about the size and extent of these neoplasms was important in the choice of surgical approaches for gross total resection of tumor.

Adult↗
PubMed1992

Cavernous sinus hemangiomas: a series, a review, and an hypothesis.

Cavernous sinus hemangiomas represent 3% of all benign cavernous sinus tumors. They are dangerous tumors because of the risk of excessive bleeding, but they are easier to dissect from surrounding structures than meningiomas because of the presence of a pseudocapsule. Three cases where total excision was achieved with minimal blood loss, without stroke, and with preservation of cranial nerve function in 2 cases are reported, and 50 cases from the literature are reviewed. Hemangiomas can be distinguished preoperatively from over one-half of meningiomas by their marked hyperintensity on T2-weighted magnetic resonance imaging. They arise within the cavernous sinus and extend laterally by dissecting between the two layers of dura lining the floor of the middle fossa. Cranial nerves III, IV, and V remained stretched over the tumor surface within the overlying dura, whereas cranial nerve VI is found within the tumor and is the most difficult cranial nerve to preserve. Principles for successful and safe excision include preoperative assessment of the safety of temporary or permanent carotid artery occlusion, obtaining early proximal carotid artery control, carefully developing the plane between the dura and the tumor pseudocapsule, early devascularization of the tumor, and avoiding "piecemeal" tumor resection. A few cases demonstrated tumor shrinkage with radiation therapy which should be considered for patients with incomplete tumor excision or who are too ill to undergo surgery.

Brain Neoplasms↗
PubMed1992

Facial nerve repair by interposition nerve graft: results in 22 patients.

Resection of tumors of the posterior cranial base may incorporate a segment of the facial nerve because of tumor infiltration, or may result in unplanned nerve injury. Immediate repair of the facial nerve by resuture or with an autogenous nerve graft is highly desirable to ensure optimal recovery of facial function. Twenty-four patients who underwent extensive surgery of the posterior skull base and facial nerve reconstruction were studied. Of these, 12 patients had preoperative facial weakness and 3 had facial palsy. All patients underwent graft reconstruction from the subarachnoid or labyrinthine portion of the facial nerve to the fallopian or extracranial segment. The greater auricular nerve was used as a graft in 14 patients, and the sural nerve in 10. Two patients died of their disease soon after surgery, and, therefore, were excluded from our follow-up. In the remaining 22 patients, the median follow-up time was 20 months. As evaluated by the House-Brackmann grading system, 45% (10/22) of the surviving patients achieved a good recovery of facial function, 36% (8/22) attained a fair recovery, and 18% (4/22) had minimal or no recovery. There was no statistical correlation between the length of the graft used and the degree or timing of clinical recovery. The surgical result obtained in all patients with complete preoperative facial palsy and in one patient with dense facial paresis was poor.

Adolescent↗
PubMed1992

The extended frontal approach to tumors of the anterior, middle, and posterior skull base.

The extended frontal approach is a modification of the transbasal approach of Derome. The addition of a bilateral orbitofrontal or orbitofrontoethmoidal osteotomy improves the exposure of midline lesions of the anterior, middle, and posterior skull base, while minimizing the need for frontal lobe retraction. The authors present a 5-year experience with 49 patients operated on via the extended frontal approach. In seven patients, the extended frontal approach was used alone; in the remaining 42, it was combined with other skull base approaches. Highly malignant tumors were removed en bloc, whereas benign tumors and low-grade malignancies were removed either en bloc or piecemeal. Reconstruction was usually performed using fascia lata, a pericranial flap, and/or autologous fat. A temporalis muscle flap or a distant microvascular free flap was required for some patients. One patient died 1 month postoperatively due to superior mesenteric artery thrombosis. Three patients had postoperative infections, two had cerebrospinal fluid leaks requiring reoperation, and four had brain contusions or hematomas. All but two patients recovered to their preoperative functional level. After an average follow-up period of 26 months (range 6 to 56 months), 64% of patients with benign lesions, 64% of patients with low-grade malignancies, and 44% of patients with high-grade lesions were alive with no evidence of disease.

Adolescent↗
PubMed1992

Temporal bone neoplasms: a report on 20 surgically treated cases.

The surgical resection of neoplasms involving the petrous bone and surrounding areas in 20 patients is reported. Technical advances described include the total resection of several tumors previously considered inoperable due to involvement of dura and brain, petrous internal carotid artery (ICA), the vein of Labbé, and adjacent areas such as the clivus and the cavernous sinus. Areas of reconstruction after resection included the ICA, the seventh and 11th cranial nerves, and the cranial base, often requiring the use of vascularized flaps. There were no intraoperative deaths. Many patients experienced significant temporary morbidity related primarily to wound healing and to lower cranial nerve palsy; however, all but three patients (all with fast-growing malignancies) returned to their preoperative functional status. During a median follow-up period of 30 months (range 17 to 63 months), the 10 patients with benign tumors and slow-growing malignancies fared well, seven being alive and disease-free. The 10 patients with fast-growing malignancies fared poorly, only two being alive without disease. This outcome appeared to be related to tumor pathology and extent of invasion; both survivors harbored tumors confined to the petrous bone. An anatomical classification system of tumor spread is introduced, which should be considered concomitantly with tumor pathology.

Adolescent↗
PubMed1992

Reconstruction of the third through sixth cranial nerves during cavernous sinus surgery.

Sixteen reconstruction procedures of the third through sixth cranial nerves were carried out in 14 patients during operations on 149 tumors involving the cavernous sinus. A direct end-to-end anastomosis was performed in five nerves, whereas in 11 cases the nerve stumps were bridged by means of an interposing nerve graft. The sixth cranial nerve was most frequently reconstructed (nine cases). In four cases, the fifth nerve or root was repaired. The third nerve was reconstructed in two patients, and the fourth nerve was repaired in only one case. Recovery of function, either partial or complete, was observed in 13 nerves: the third in two instances, the fourth in one, the fifth in three, and the sixth in seven. No return of function occurred in three nerves. In patients with a successful recovery of cranial nerve function, either binocular function or the cosmetic result was improved. These results suggest that repair of the third through sixth cranial nerves injured during surgery should be pursued in suitable patients.

Abducens Nerve↗
PubMed1992

Emergency embolectomy for embolic occlusion of the middle cerebral artery after internal carotid artery balloon test occlusion. Case report.

Balloon test occlusion of the internal carotid artery (ICA) is useful in preoperatively assessing the risk of temporary occlusion or permanent sacrifice of the carotid artery. The incidence of symptomatic complications from this procedure is 1.7%. The case is reported of a 57-year-old woman in whom a balloon test occlusion of the left ICA was attempted. She developed a left ICA dissection/occlusion with subsequent embolization to the left middle cerebral artery, leading to right-sided hemiplegia and expressive aphasia. She was successfully treated by an emergency embolectomy followed by surgical repair of the left ICA, with an excellent outcome. This case represents the most serious complication encountered by the authors in more than 300 balloon test occlusions. Means of avoiding this complication during balloon test occlusion as well as the important factors in managing this problem are emphasized.

Carotid Artery, Internal↗
PubMed1992

Late course of preserved hearing and tinnitus after acoustic neurilemoma surgery.

The late course of preserved hearing and tinnitus following retrosigmoid transmeatal surgery for acoustic neurilemoma is reported. Over a period of 5 years, useful hearing was preserved in 15 patients after preservation was attempted in 42 patients. In five patients the hearing was better than the preoperative level; in three it was worse. Three patients developed delayed worsening and fluctuations of hearing in the surgically treated ear during a median follow-up period of 2 1/2 years. While the exact reason for such worsening was not clear in two patients, in one patient it appeared that the muscle graft placed in the internal auditory canal after tumor resection resulted in fibrosis and compromise of the cochlear nerve. The causes of delayed worsening of hearing in the absence of tumor recurrence are analyzed, and possible treatment and methods of prevention of worsening are suggested. In six patients, tinnitus persisted after surgery in the ear with successful preservation of hearing, but hearing was not worsened and the tinnitus was not bothersome to the patient. In one patient with preoperative tinnitus, hearing was not preserved and tinnitus persisted sufficiently to necessitate reexploration and cochlear nerve section.

Adult↗
PubMed1992

The subtemporal, transcavernous, anterior transpetrosal approach to the upper brain stem and clivus.

The temporal lobe, posterolateral cavernous sinus, tentorium, and petrous apex restrict anterolateral surgical access to lesions of the upper brain stem and clivus. The authors describe a modified transpetrosal approach that enhances the exposure of clival chordomas and aneurysms of the basilar artery bifurcation. An intradural and extradural subtemporal approach is combined with division of the tentorium and superior petrosal sinus, posterolateral dissection of the cavernous sinus, and intradural removal of the petrous bone from its apex to the cochlea. The indications, advantages, and disadvantages of this subtemporal, transcavernous, anterior transpetrosal approach are described in detail, along with its use in six patients.

Adult↗
PubMed1992

Direct vein graft reconstruction of the cavernous, petrous, and upper cervical internal carotid artery: lessons learned from 30 cases.

The authors report a series of 30 patients who underwent reconstruction of the internal carotid artery (ICA) at the skull base with the saphenous vein during the surgical management of lesions at the cranial base. This group represents about 9% of the total patients in whom the ICA in the cavernous or petrous segment was manipulated either during the surgical approach or dissection from the tumor. Two of these patients failed a clinical balloon test occlusion of the ICA, and, in 9 patients, cerebral blood flow during balloon test occlusion dropped to between 15 to 30 ml/100g/min. The patency rate is 86% over a mean follow-up time of 18 months. Of the 4 patients with graft occlusion, 3 were asymptomatic. The fourth patient who suffered ICA dissection with graft occlusion subsequently died from a massive cerebral infarction. Three patients with inadequate collateral circulation sustained minor strokes as the result of the temporary ICA occlusion during the grafting, but all are capable of leading independent lives. Two patients suffered acute graft occlusion within 12 hours of the surgery and underwent successful revision of the graft. None of the grafted patients suffered delayed occlusion or ischemic or embolic problems. The patients with malignant tumors died within 2 years of the operation from the original disease; total tumor removal was accomplished in 14 of the 19 patients with benign tumors. The aneurysms were successfully eliminated in all 5 patients. The lessons learned from this experience are discussed.

Adolescent↗
PubMed1991

Management of tumours involving the cavernous sinus.

The operative experience with 137 tumours of the cavernous sinus at the University of Pittsburgh during the past 7 years is reported. The importance of the normal and tumour-infiltrated cavernous sinus anatomy and imaging is delineated. 63% of the tumours are benign, primarily meningiomas, for which an anatomical grading system is presented. The various operative approaches to the cavernous sinus are described. 88% of the meningiomas were totally resected. There was a 1.5% operative mortality and 1.5% severe morbidity rate. Initial ipsilateral opthalmoplegia progressively improved in the majority of patients. For all patients with at least 6 months of follow up of benign tumours, the intracavernous tumour recurrence rate was 3% and total recurrence rate was 6%.

Brain Neoplasms↗
PubMed1991

Surgical management of clival meningiomas.

The surgical management of intradural clival tumours is difficult due to the relative inaccessibility of the clivus through traditional neurosurgical approaches, and the intimate relationship of such tumours to critical neurovascular and brainstem structures. This report concentrates on the experience with clival meningiomas, which are the most common intradural clival tumours. Between July 1983 and July 1990, 52 patients with petroclival meningiomas underwent surgical excision of their tumours. A variety of skull base approaches were utilized to obtain wide tumour exposure with minimal brain retraction. Large or giant tumours required multiple approaches and staged removal of tumour. Tumour resection was evaluated by a standard protocol of postoperative MR or CT scans. Total tumour resection was achieved in 38 cases (73%), subtotal resection in 11 (21%) and partial resection in 3 (6%). Follow-up has ranged from 4 to 83 months. Two patients had recurrence of tumour requiring re-operation with one receiving additional external beam radiation. Two postoperative deaths occurred, one from pneumonia and another from infectious complications. The most common postoperative morbidity were lower cranial nerve palsy, aspiration peumonia and temporary hemiparesis.

Adult↗
PubMed1991

Extradural petrous bone and petroclival neoplasms.

Extradural petroclival tumours are composed of a spectrum of histological and anatomical configurations dictating a variety of surgical approaches. The experience with 68 such tumours operated at the University of Pittsburgh is presented, emphasizing the basal subfrontal and lateral approaches. 85% of these tumours are benign or low-grade malignancies, with 62% of these totally resected, resulting in a 5.4% recurrence rate. The operative mortality was 1.5% and major morbidity 3%. Well-planned surgery based on precise anatomical knowledge and imaging is the basis of treatment for petroclival tumours.

Combined Modality Therapy↗
PubMed1991

Surgical management of anteriorly placed lesions at the craniocervical junction--an alternative approach.

Lesions ventral to the neuraxis at the craniocervical junction can pose a significant management problem because of their strategic location. Conventional posterolateral approaches sometimes may not permit adequate visualization of the entire base of the tumor without significant manipulation of the brain stem and spinal cord. The anterior transoral and extrapharyngeal approaches are alternate ways of exposing this region without neural retraction. However, these approaches do not provide adequate exposure of the lateral margins of the tumour, there is no control of the vertebral arteries and cranial nerves and the tumor--brain stem interface is not seen till the end of the operation. A lateral approach is described in this report which involves additional bone removal in the region of the mastoid process and the articular pillars in order to provide a true lateral perspective for the removal of these tumors. The advantages include excellent definition of the interface between the tumor and cord/brain stem without manipulation of the neuraxis, control of the ipsilateral vertrebral artery and caudal cranial nerves, ability to remove the intra- and extradural portions of the tumor in one operation and the ability to perform an immediate bony fusion if necessary. The application of this approach in the management of 9 patients with a variety of intra- and extradural lesions at the clivus and foramen magnum is discussed.

Adolescent↗
PubMed1991

Carotid and cranial nerve reconstruction after removal of cavernous sinus lesions.

During the last 7 years, approximately 170 neoplasms, and 35 vascular lesions involving the cavernous sinus were treated by the first two authors. During the treatment of such lesions, the direct vein graft reconstruction of the internal carotid artery from the petrous to the supraclinoid or infraclinoid ICA was performed in 23 patients. Graft occlusion occurred in 3 patients and in one of these, it was successfully salvaged by placing a long venous graft from the extracranial ICA to the M3 segment of the middle cerebral artery. The latter 3 patients were neurologically normal. One patient with significant atherosclerotic disease suffered the dissection of the distal internal carotid artery with the graft being patent. The suturing technique. This patient eventually died. Two patients with severely compromised collateral circulation suffered minor strokes due to the temporary occlusion of the ICA. This has been avoided in the more recent patients by the adoption of brain protection techniques such as moderate hypothermia, induced hypertension, and barbiturate coma. Low dose heparin therapy during grafting and high dose intravenous steroids prior to the grafting also appear to be beneficial. Direct vein graft reconstruction of the intracavernous carotid artery is a valuable tool during the management of cavernous sinus lesions. The advantages and disadvantages of this technique as well as the pros and cons of other revascularization techniques will be discussed. During microsurgical removal of cavernous sinus lesions, the cranial nerves III-VI were reconstructed by direct resuture or by nerve grafting in 16 patients. In the majority of these patients, recovery of cranial nerve function was observed, which was very encouraging.(ABSTRACT TRUNCATED AT 250 WORDS)

Carotid Arteries↗
PubMed1991

Facial translocation for cranial base surgery.

The complexity of cranial base surgery is a reflection of skull base anatomy as well as technical demands for maximum visualization, control of essential structures, adequate tumor resection and/or reconstruction. Facial translocation has been developed as a new approach to cranial base. It consists of extensive modular facial disassembly which includes displacement of composite facial soft tissue flap and craniofacial skeleton. It creates surgical field with epicenter in nasopharynx and infratemporal fossa allowing easy expansion into sphenoid bone and cranial fossae as well as craniovertebral junction. Reconstruction is functional and esthetic. Versatility of this approach permits expansion into neighboring craniofacial regions. During a 14-month period (11/88-12/89), this facial translocation approach to cranial base was utilized in 20 patients. The approach provided excellent visualization of the involved cranial base permitting oncological as well as reconstructive procedures. All patients healed primarily. Two patients were reoperated on at 4 and 6 months postoperatively; one for a bone graft infection and the other for tumor recurrence. The facial translocation approach offers favorable exposure of the critical zones of cranial base resulting in increased surgical safety and benefit of cranial base surgery.

Adolescent↗