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Biomedical subjects

C N Sen

Publications and source records attributed to C N Sen.

At least 19 recordsLinked to original sources
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

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↗
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

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

Facial translocation approach to the cranial base.

Facial translocation is a new approach which has been developed for surgical management of extensive lesions of the anterolateral cranial base, including the nasopharynx, sphenoid sinus, clivus, infratemporal fossa, superior orbital fissure, and cavernous sinus. Temporary displacement of the craniofacial skeleton allows direct, wide access to this complex anatomic area, while giving the surgeon a high degree of control over critical neural and vascular structures.

Adolescent↗
PubMed1991

Midfacial split for access to the central base.

The technique of the midfacial split for access to the central cranial base is described. It provides--using bilateral facial osteotomies and soft tissue mobilization--a unified surgical field extending in the sagittal plane from the anterior cranial fossa floor and sphenoid sinus to the level of the fourth cervical vertebral body. In the axial plane, the periphery of the surgical access may extend to the jugular fossae and the hypoglossal canals. Experiences and results in eight patients are presented.

Chondrosarcoma↗
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

The transoral approach for the management of intradural lesions at the craniovertebral junction: review of 7 cases.

The main difficulty in dealing with intradural lesions located ventrally in the region of the craniovertebral junction (CVJ) is related to their relative inaccessibility. Posterolateral approaches involve some manipulation of the brain stem and provide limited access because of the necessity of working between the cranial nerves. Even then, the view of the ventral midline and across is limited. The transoral approach, which has been widely used for the management of extradural lesions in this area, is also useful for the treatment of intradural lesions. It provides an unimpeded although somewhat restricted, view of the ventral aspect of the CVJ without the need for brain retraction. The cranial nerves and vertebral arteries are not interposed between the surgeon and the lesion. The risks of cerebrospinal fluid leakage and infection are greatly diminished by the use of fibrin adhesive and prolonged diversion of the cerebrospinal fluid. The use of this approach, together with its technical difficulties and results, in the management of seven purely intradural lesions located ventrally at the CVJ, is discussed.

Adult↗
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↗
PubMed1991

Craniofacial disassembly in the management of skull-base tumors.

Craniofacial disassembly now plays a major role in the management of tumors that invade the skull base. The chief advantage of this technique is the greatly improved operative exposure it provides, allowing the surgeon to resect such tumors more completely and with an added margin of safety. Microneurosurgical advances have made it possible to preserve cranial nerve function in many cases, and modern reconstructive methods employing vascularized flaps have helped to reduce postoperative complications and deformity. Through the combination of craniofacial techniques and oncologic principles, the outlook for patients with skull base tumors is improving.

Adult↗
PubMed1990

Recordings from the facial nucleus in the rat: signs of abnormal facial muscle response.

On the basis of results of electrophysiological studies in patients undergoing microvascular decompression (MVD) operations to relieve hemifacial spasm (HFS), we have postulated that the abnormal muscle response characteristically found in patients with HFS is the result of irritation of the facial nerve by the blood vessel that is compressing the facial nerve near its exit from the brainstem in these patients. This abnormal muscle response is seen when one branch of the facial nerve is electrically stimulated and recordings are made from muscles that are innervated by other branches of the facial nerve. We further hypothesized that the facial nucleus is hyperactive in patients with HFS and that the spasm and the abnormal muscle response are results of a phenomenon known as "kindling". These hypotheses are supported by recent studies showing that chronic electrical stimulation of the facial nerve trunk in rats near the brainstem results in an abnormal muscle response that is similar to that seen in patients with HFS. In this paper, we present the results of recording from the facial motonucleus in rats that had been subjected to repeated electrical stimulation of the facial nerve. The results indicate that the abnormal muscle response in these rats was caused by changes in the function of the facial motonucleus. We interpret these results as showing that the physiological abnormalities that give rise to the signs of HFS in man are located in the facial motonucleus, and that the changes in the function of the nucleus are produced by chronic antidromic neutral activity resulting from close contact between a blood vessel and the facial nerve.

Animals↗
PubMed1990

An extreme lateral approach to intradural lesions of the cervical spine and foramen magnum.

Meningiomas and neurofibromas are the most common intradural extramedullary tumors of the foramen magnum and cervical spine. Many of these tumors are located ventral or ventrolateral to the spinal cord and medulla. Posterior approaches, although adequate for the management of most of these tumors, can sometimes result in incomplete removal of the tumor and exacerbation of the neurological deficits. Although the transoral and transcervical approaches provide a direct route to the tumor, the exposure of the lateral margins in the case of large tumors is inadequate. In addition, because of the removal of vertebral bodies, subsequent fusion may be necessary. In the present report, an extreme lateral approach to the foramen magnum and cervical spine for the removal of intradural tumors is described. The approach provides a lateral exposure of the tumor-cord/stem interface, thus permitting safe dissection without retraction of the cord. The entire longitudinal and lateral extent of the tumor and also its extradural extension can be can be managed by this approach. This approach can be considered in such a group of patients harboring entirely ventral or recurrent tumors for which the conventional posterior approach has failed. Six patients who underwent this procedure are described to illustrate its application.

Adolescent↗
PubMed1990

Facial translocation: a new approach to the cranial base.

Nasopharynx, clivus, and cavernous sinus are difficult regions of the cranial base in which to perform oncologic surgery. We have developed an approach to this area by using facial soft tissue translocation and craniofacial osteotomies. Surgical field obtained at the skull base can extend from the contralateral eustachian tube to ipsilateral geniculate ganglion. It includes the nasopharynx, clivus, sphenoid, and cavernous sinus, as well as the entire infratemporal fossa and superior orbital fissure. Our experience with this technique in 12 patients is reported. All patients healed primarily.

Face↗
PubMed1990

Anterior cranial base reconstruction: role of galeal and pericranial flaps.

Reconstruction of surgical defects in 30 patients undergoing surgery of the anterior cranial base was performed using pericranial, galeopericranial, and galeal scalp flaps. Twenty-seven patients had resection of neoplasms, the majority of which were malignant. Fifty-seven percent of patients received prior therapy consisting of surgery and/or radiotherapy. Adequate healing of the cranial base was noted in all cases without persistent cerebrospinal fluid leaks, meningitis, or brain herniation. Mucosalization of the intranasal surface was noted. No skin grafts were used. At a median follow-up of 13 months, 67% of patients were alive with no evidence of disease. The pericranial, galeopericranial, and galeal flaps are highly reliable, versatile, and well suited for reconstruction of the anterior cranial base.

Adolescent↗
PubMed1990

Saphenous vein graft bypass of the cavernous internal carotid artery.

Saphenous vein graft reconstruction was performed from the petrous to the supraclinoid internal carotid artery (ICA) to replace the cavernous ICA in six patients during direct intracavernous operations. Four of these patients had intracavernous neoplasms with invasion of the ICA and two had intracavernous ICA aneurysms that could not be clipped or occluded with intraluminal balloons. All but one patient had evidence of poor collateral flow reserve in a balloon occlusion test of the ICA. The superficial temporal artery was not present in four patients, was minuscule in one, and was damaged during the initial dissection in another, making it unsuitable for superficial temporal-to-middle cerebral artery branch anastomosis. Blood flow within the graft could not be established intraoperatively in one patient (who had excellent collateral circulation) due to the small size of the vein (3 mm). In all others, the grafts were patent on follow-up arteriography and transcranial Doppler studies. Three patients who had severe reduction of cerebral blood flow during test occlusion of the ICA exhibited temporary hemispheric neurological deficits postoperatively; the deficits were related to the duration of temporary ICA occlusion. All three recovered completely without evidence of infarction on computerized tomography (CT). One patient who clinically could not tolerate the balloon occlusion test of the ICA also had temporary neurological deficits with good recovery but showed evidence of border-zone infarction on CT scans. The present role of saphenous vein graft bypass of the cavernous ICA is discussed.

Adult↗
PubMed1990

The subtemporal and preauricular infratemporal approach to intradural structures ventral to the brain stem.

The subtemporal and preauricular infratemporal operative technique is an approach to the skull base through the anterior portion of the petrous temporal bone and is used for the removal of predominantly extradural tumors in this region. The present study, based on dissection of human cadavers, describes the use of this approach for the management of intradural lesions in the region of the clivus. Its main advantages include avoidance of brain retraction, the use of an extrapharyngeal route, and exposure of the ventral aspect of the pons and medulla and related structures caudal to the trigeminal root. This approach can easily be combined with an intradural subtemporal approach to provide additional exposure of the superior clivus rostral to the trigeminal root. Combining the two approaches provides direct access to the ventral surface of the entire brain stem from the dorsum sellae to the hypoglossal foramina. Five patients with lesions in the clivus and petrous apex have been operated on via this approach. Details of the anatomical aspects of the approach and its applications are presented.

Adult↗