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Biomedical subjects

O Al-Mefty

Publications and source records attributed to O Al-Mefty.

At least 37 records · Page 2Linked to original sources
PubMed1998

A combined microsurgical skull-base and endovascular approach to giant and large paraclinoid aneurysms.

BACKGROUND: The treatment of giant and large paraclinoid aneurysms remains challenging. To improve exposure, facilitate the dissection of aneurysms, assure vascular control, reduce brain retraction and temporary occlusion time, enable simultaneous treatment of associated lesions, and achieve more successful treatment of "difficult" (atherosclerotic and calcified) aneurysms, we combined the skull-base approach with endovascular balloon occlusion of the internal carotid artery (ICA) and suction decompression of the aneurysm. METHODS: Sixteen female patients were treated, eight with giant aneurysms and eight with large aneurysms. Eight aneurysms occurred on the right side and eight on the left. Eight patients had an additional aneurysm; five were clipped during the same procedure. Three patients had infundibular arterial dilation. One patient had an associated hemangioma of the ipsilateral cavernous sinus. The cranio-orbital-zygomatic approach was used for all patients. The anterior clinoid was drilled, and the optic nerve was decompressed, dissected, and mobilized. Transfemoral temporary balloon occlusion of the ICA in the neck was followed by placement of a temporary clip proximal to the posterior communicating artery. Suction decompression was then applied. All aneurysms were then successfully clipped, except one that had a calcified neck and wall that could not be collapsed. Intraoperative angiography performed in 13 of 15 patients with clipped aneurysms confirmed obliteration of the aneurysm and patency of the blood vessels. RESULTS: Postoperative results were good in 14 patients. One patient had right-sided hemiplegia and expressive aphasia, which improved after rehabilitation. One patient with an additional basilar tip aneurysm clipped simultaneously died on the fifth postoperative day because of intraventricular hemorrhage. The origin of bleeding could not be determined on autopsy. Surgical difficulties and morbidity stemmed mainly from a severely calcified or atherosclerotic aneurysmal neck. CONCLUSION: The combination of skull-base approaches and endovascular balloon occlusion coupled with suction decompression is a successful option for the treatment of these challenging aneurysms.

Adult↗
PubMed1998

Dural arteriovenous malformations of the transverse/sigmoid sinus acquired from dominant sinus occlusion by a tumor: report of two cases.

OBJECTIVE AND IMPORTANCE: Debate continues regarding the pathogenesis of dural arteriovenous malformations (dAVMs). The prevailing theory is that dAVMs are acquired lesions that occur after thrombosis of the dural venous sinus. CLINICAL PRESENTATION: We report unique cases of two patients having different tumors (one meningioma and one glomus jugulare paraganglioma) that occluded the ipsilateral transverse and sigmoid sinuses, respectively, and were associated with dAVMs. In each patient, the occluded venous sinus was the dominant sinus. CONCLUSION: Our experience with these patients supports the hypothesis that dAVMs are acquired and induced lesions that may occur after sinus occlusion. We suggest that the occlusion of the dominant transverse/ sigmoid sinus is a major contributing factor to the development of dAVMs because of the inability of the contralateral (nondominant) sinus to handle the venous flow from the obstructed (dominant) side.

Arteriovenous Fistula↗
PubMed1998

Bridging veins on the tentorial surface of the cerebellum: a microsurgical anatomic study and operative considerations.

OBJECTIVE: When using the median infratentorial supracerebellar approach, all or numerous bridging veins over the cerebellar surface must be sacrificed. Such sacrifice potentially causes cerebellar venous infarction, especially when excessive cerebellar retraction is applied. To prevent such potential complications, neurosurgeons must have adequate knowledge of the anatomy of the bridging veins, particularly the hemispheric bridging veins. METHODS: In 14 cadaveric specimens (26 sides), the number, locations, and tributaries of both the vermian and hemispheric bridging veins between the superior surface of the cerebellum and the tentorium were examined with the aid of an operating microscope. In addition, particular attention was given to the distribution patterns and collateral pathways of the hemispheric bridging veins. RESULTS: The average number of vermian bridging veins per cerebellum was 3.24. The average number of hemispheric bridging veins per side was 1.69, and they were most frequently located in the intermediate third of the hemisphere (59.0%). The distribution patterns of the hemispheric bridging veins were classified into six groups according to the draining patterns of each cerebellar hemisphere. Each hemispheric bridging vein usually had several collateral pathways between other draining veins. The most prominent collateral pathways of the hemispheric bridging veins frequently connected with the vermian bridging veins. CONCLUSION: Anatomic familiarity with the bridging veins can minimize their intraoperative sacrifice and avert subsequent postoperative complications. This knowledge also assists in planning the best approach to the pineal region.

Cerebellum↗
PubMed1998

Academic chairmen.

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Academic Medical Centers↗
PubMed1997

Petrous apex cholesterol granulomas: evolution and management.

Petrous apex cholesterol granulomas result from obstruction of the normal aeration of the petrous air cells and have traditionally been treated by drainage and stent placement via a transtemporal approach. The immediate results were quite satisfying, but recurrence rates as high as 60% have been reported in some series. The authors present their experience treating 14 patients with petrous apex cholesterol granulomas. An extended middle fossa approach and a petrosal approach were used for eight and two patients, respectively. All underwent complete removal of the granuloma and cyst wall followed by obliteration of the cavity with a pedicled strip of temporalis muscle. No recurrences were seen at a mean follow-up period of 3.8 years. Four patients who did not undergo surgery are being followed clinically and with serial magnetic resonance images. Additionally, the clinical and radiographic findings in this series give new insights into the origin and continued growth of these lesions and confirm what had been described previously only in experimental models. It is concluded that petrous apex cholesterol granulomas feature a continuum of both clinical and radiographic findings and radical removal via an extended middle fossa approach is advocated.

Adolescent↗
PubMed1997

The transcallosal-transforaminal approach to the third ventricle with regard to the venous variations in this region.

Surgical approaches to lesions located in the anterior and middle portions of the third ventricle are challenging, even for experienced neurosurgeons. Various exposures involving the foramen of Monro, the choroidal fissure, the fornices, and the lamina terminalis have been advocated in numerous publications. The authors conducted a microsurgical anatomical study in 20 cadaveric brain specimens (40 hemispheres) to identify an exposure of the third ventricle that would avoid compromising vital structures. An investigation of the variations in the subependymal veins of the lateral ventricle in the region of the foramen of Monro was performed, as these structures are intimately associated with the surgical exposure of the third ventricle. In 16 (80%) of the brain specimens studied, 19 (47.5%) of the hemispheres displayed a posterior location of the anterior septal vein-internal cerebral vein (ASV-ICV) junction, 3 to 13 mm (average 6 mm) beyond the foramen of Monro within the velum interpositum, not adjacent to the posterior margin of the foramen of Monro (the classic description). Based on this finding, the authors advocate opening the choroidal fissure as far as the ASV-ICV junction to enlarge the foramen of Monro posteriorly. This technique achieves adequate access to the anterior and middle portions of the third ventricle without causing injury to vital neural or vascular structures. The high incidence of posteriorly located ASV-ICV junctions is a significant factor influencing the successful course of surgery. Precise planning of the surgical approach is possible, because the location of the junction is revealed on preoperative neuroradiological studies, in particular on magnetic resonance venography. It can therefore be determined in advance which foramen of Monro qualifies for posterior enlargement to gain the widest possible access to the third ventricle. This technique was applied in three patients with a third ventricular tumor, and knowledge of the venous variations in this region was an important resource in guiding the operative exposure.

Adolescent↗
PubMed1996

Intravagal paragangliomas: report of four cases.

The intravagal paraganglioma is a very rare tumor of the head and neck that accounts for only 5% of the paragangliomas in that area. A painless mass in the high neck with extension into the peripharyngeal space is the most common characteristic of this tumor. Malignant paragangliomas with invasion of the cervical lymph nodes and carotid artery have been reported, but the presence of metastasis, rather than the histological findings, is the only parameter for classifying them as malignant tumors. Despite the numerous descriptions of the efficacy of radiation therapy, the histological findings of irradiated specimens have shown little effect of radiation therapy on the chief cells. The only curative therapy for intravagal paragangliomas is the total resection of the tumor. Using the supra-adventitia dissection plane, we were able to achieve total resections in four cases of complex intravagal paraganglioma. The surgical management of these cases was complex because of the following: 1) misdiagnosis as a carotid body tumor, 2) previous radiation therapy and surgical procedure, 3) association with glomus jugulare, and 4) a giant tumor with invasion of the temporal bone and encasement of the internal carotid artery. We report the surgical management of intravagal paragangliomas and the role of radiation therapy, hormonal secretion, and rehabilitation care.

Adult↗
PubMed1996

Cranial chordomas in children and adolescents.

Chordomas are rare tumors that usually occur in adults. This report describes four cases of intracranial chordomas treated in patients 20 years of age or younger by the senior author (O.A.M.) during a 4-year period. The authors also reviewed the literature on pediatric patients, which revealed that the clinical presentations, histological patterns, and behaviors of these tumors differ considerably depending on whether the patient is younger or older than 5 years of age. The younger population had a wider range of presenting symptoms, a greater prevalence of atypical histological findings with aggressive behavior, a greater range of cellularity than the classic chordomas, and a higher instance of metastasis; it showed no chondroid component compared to a 17.1% instance in the older patients. The prognosis for patients with a chordoma is related directly to the histological pattern of the tumor; the atypical chordoma carries a poor prognosis. The prognoses for children older than 5 years of age with a classic or chondroid tumor were not significantly different (p=0.788). At follow up, the difference in survival rates between patients undergoing surgery plus radiation therapy and those who had surgery alone was statistically significant (p=0.00446). No correlation was found between radical resection or radiation therapy and an improved prognosis for patients younger than 5 years of age who had a tumor with an atypical histological pattern. This study identifies and delineates the distinction between these age groups and provides a review of the potential prognostic factors.

Adolescent↗
PubMed1995

Skull base approaches for posterior circulation aneurysms.

With the emergence of skull base surgery, surgical approaches have been developed and redefined, providing surgeons with accessible avenues to difficult lesions of the cranial base. Although the majority of lesions to which these techniques have been applied have been for tumors, we find that these skull base approaches can equally provide access to difficult vascular lesions, especially complex aneurysms of the posterior circulation. In this report three different skull base approaches were used in four patients for the treatment of posterior circulation aneurysms. A cranio-orbital-zygomatic approach was used for the acute stage of a ruptured basilar tip artery anenrysm and for a giant posterior cerebral artery aneurysm. A petrosal approach was used for a ruptured basilar trunk aneurysm, and the transcondylar approach was used for a vertebral artery aneurysm. Each approach provides a wide field and excellent exposure of vital structures with minimal brain retraction. Neck clipping of the aneurysms was successfully achieved in all cases. We believe that our skull base approaches facilitate the surgical treatment of posterior circulation aneurysms.

Journal Article↗
PubMed1991

Open-door maxillotomy approach for lesions of the clivus.

The transpalatal route to the clival region has been used to approach both extradural and intradural lesions. Classic transpalatal surgery, however, entails a partial splitting of the soft palate or some form of palatal retraction, which leaves behind a bony palate that hinders surgical exposure. When necessary, operative exposure can be enhanced by an open-door maxillotomy approach that uses a combination of a Le Fort I osteotomy of the maxilla and a paramedian sagittal split of the hard palate. The nasal septum is translocated to create a wide contiguous oronasal aperture through which the clival region can be reached unobstructed. This technique was used in three patients. No significant complications were observed in any patient. Features of this extended transpalatal approach, including indications and adjunctive measures to minimize potential complications, are discussed.

Journal Article↗
PubMed1990

Clinoidal meningiomas.

Anterior clinoidal meningiomas are frequently grouped with suprasellar or sphenoid ridge meningiomas, masking their notorious association with a high mortality and morbidity rate, failure of total removal, and recurrence. To avoid injury to encased cerebral vessels, most surgeons are content with subtotal removal. Without total removal, however, recurrence is expected. Recent advances in cranial-base exposure and cavernous sinus surgery have facilitated radical total removal. The author reports 24 cases operated on with vigorous attempts at total removal of the tumor with involved dura and bone. This experience has distinguished three groups (I, II, and III) which influence surgical difficulties, the success of total removal, and outcome. These subgroups relate to the presence of interfacing arachnoid membranes between the tumor and cerebral vessels. The presence or absence of arachnoid membranes depends on the origin of the tumor and its relation to the naked segment of carotid artery lying outside the carotid cistern. Total removal was impossible in the three patients in Group I, with postoperative death occurring in one patient and hemiplegia in another. Total removal was achieved in 18 of the 19 patients in Group II, with one death from pulmonary embolism. In the two patients in Group III, total removal without complications was easily achieved.

Adult↗
PubMed1989

An orbitocranial approach to complex aneurysms of the anterior circulation.

A surgical approach to the skull base was developed in cadavers and then used in the treatment of patients with complex aneurysms of the anterior circulation. The operative method involves removal of portions of the orbital rim, orbital roof, and sphenoid bone. By removing the orbital rim and a portion of the orbital roof, multidirectional viewing is possible. This is important when dealing with the anterior aspect of the cavernous sinus and anterior clinoid process, as must frequently be done when isolating the neck of an ophthalmic aneurysm. The optic canal is opened wide and the optic nerve mobilized, allowing resection of the dura propria covering the cavernous carotid artery. Clip placement is performed in an anteroposterior plane, thus lessening the chance for compromise of the internal carotid artery. The low approach alleviates brain retraction and the small flap minimizes brain exposure. The approach also allows preservation of the arterial and neural supply to the frontalis and temporalis muscles, thereby preventing postoperative cosmetic deficits. During the past year and a half, this approach has been employed in 25 patients with difficult aneurysms of the anterior circulation. The difficulties of these cases stemmed from their odd location, size, or complex anatomy. Although periorbital edema may have been more severe during the first postoperative week, overall improved cosmesis was achieved.

Adult↗
PubMed1988

Surgery of tumors invading the cavernous sinus.

Potential injury to neurovascular structures within the cavernous sinus often prohibits total removal of various cranial base tumors. This report discusses the rationale of direct cavernous sinus surgery and describes a surgical technique refinement as evolved from experience in 18 histologically benign operative cases. The nature of tumor extension mandated entry to the sinus, either through the superior or lateral wall or both. The operative microscope facilitated dissecting and preserving the carotid artery and cranial nerves transversing the sinus. Venous bleeding was controlled by packing. There was one death unrelated to cavernous sinus surgery. Five patients, however, had complications related to cavernous sinus surgery, including hemiplegia in one patient and cranial nerve palsy in four.

Adolescent↗
PubMed1988

Central spinal cord injury: magnetic resonance imaging confirmation and operative considerations.

A case of central cervical spinal cord injury, confirmed by magnetic resonance imaging (MRI) and treated by myelotomy, is presented. After recovering well from his central cord syndrome and walking with assistance, the patient developed a rapidly progressive myelopathy beginning 2 months after injury. His main injury localized clinically to the C8, T1 level; but central cord abnormalities were identified 3 months after injury at the C6 level by MRI: a high signal intensity on the proton density sequence and a low-signal intensity on the T1-weighted sequence. At operation 41/2 months after his injury and 1 month after complete paraplegia, a myelotomy at C6 failed to reveal any cavity (syrinx) but instead disclosed only intense gliosis inside a slightly atrophic spinal cord. Rapid clinical improvement ensued. Secondary syringomyelia may be an endstage condition after spinal cord insults that trigger a progressive, pathophysiological reaction leading to central cord necrosis. In selected cases, myelotomy may interrupt this MRI-identified, nosogenic process before cavitation has occurred.

Adult↗
PubMed1988

Petrosal approach for petroclival meningiomas.

Thirteen patients harboring large petroclival meningiomas are reported. The evolution of the petrosal approach is discussed, and modifications for improvement in surgical technique are described. There was no mortality in this series, and total removal was achieved in all but two patients. Morbidity included cranial nerve deficit, pulmonary embolism, and hemiparesis.

Adult↗
PubMed1988

Optic nerve decompression in osteopetrosis.

Osteopetrosis is a rare disorder characterized by generalized increased skeletal density with abnormalities of bone modeling. The skull base is usually involved. Loss of vision with optic nerve atrophy is the most common neurological finding and is traditionally believed to be the result of optic nerve compression within the compromised optic canal. However, retinal degeneration has recently been described and is hypothesized to be the etiology of the visual loss (thus challenging the value of surgical decompression). The authors report their experience with six children suffering from osteopetrosis and severe visual loss. All six patients underwent bilateral microsurgical optic nerve decompression through a supraorbital craniotomy. Improvement in visual acuity occurred postoperatively in five patients, and none had complications. Two technical points are emphasized: 1) optic nerve decompression should be wide and include not only unroofing of the canal but also drilling along both sides of the optic nerve, and 2) the thick, irregular, and highly domed orbital roof should be smoothed down by high-speed drilling to facilitate surgical exposure with minimal retraction of the frontal lobe.

Child↗
PubMed1988

Myelopathic cervical spondylotic lesions demonstrated by magnetic resonance imaging.

Eighteen cases are presented in which magnetic resonance (MR) imaging demonstrated two types of lesions in patients with cervical spondylotic myelopathy. In the first type, localized spinal cord changes at the level of compression, consistent with myelomalacia, were revealed best with T2-weighted images as high-intensity spinal cord signals. In the second type, lesions consistent with either cystic necrosis or secondary syrinx were noted locally, and/or extending longitudinally up, and/or down inside the spinal cord. These latter lesions were best revealed as low-intensity signals on T1-weighted MR images and as a signal-void sign (moving fluid) on proton-density or T2-weighted MR images. It is suggested that segmental lesions at the level of the spondylotic bar represent early proton changes from pressure in and around the same zones that evolve into gray-matter enhancement regions shown as "snake-eyes" on delayed computerized tomography (CT) after myelography. The longitudinal lesions are thought to be the same pencil-shaped zones of cystic necrosis evolving into a secondary syrinx in the late stages (and usually found in the anterior portion of the dorsal columns during delayed CT after myelography). As spinal MR imaging continues to improve, these lesions will be demonstrated more clearly within the cord substance.

Adult↗