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Ossama Al-Mefty

Publications and source records attributed to Ossama Al-Mefty.

At least 19 recordsLinked to original sources
PubMed2006

Increasing exposure of the petrous internal carotid artery for revascularization using the transzygomatic extended middle fossa approach: a cadaveric morphometric study.

OBJECTIVE: When internal carotid artery (ICA) sacrifice is planned in the management of difficult tumors or aneurysms at the cranial base, the petrous ICA may be a useful site for anastomosis for interpositional vascular bypass. However, exposure of the artery and performing an anastomosis in this region may be technically challenging because of the narrow working corridor. The authors describe a transzygomatic extended middle fossa approach that maximizes the exposure of the petrous ICA for performing the difficult anastomosis. METHODS: Bilateral dissections were performed on eight silicone-injected cadaveric head specimens. Exposure of the entire petrous ICA (horizontal segment, genu, and vertical segment) using the transzygomatic extended middle fossa approach was performed by the following steps. A frontotemporal craniotomy was performed followed by a zygomatic osteotomy. The temporal lobe dura was elevated extradurally to expose the posterior cavernous sinus and floor of the middle fossa. The middle fossa rhomboid was identified, which is bordered by V3 anteriorly, the GSPN laterally, the arcuate eminence posteriorly, and the petrous edge medially. Bone drilling was performed in the middle fossa rhomboid and Glasscock's triangle with care not to violate the cochlea. The horizontal and vertical segments of the petrous ICA were skeletonized entirely and mobilized from carotid canal. The V3 segment of the trigeminal nerve was retracted anteriorly to obtain more distal exposure of the ICA. An osteoplastic bone flap of the middle fossa floor lateral to the ICA was removed to increase the working space. A morphometric analysis was performed, quantifying the petrous ICA exposure, the surgical working corridor, and the angles of exposure. RESULTS: On average, the length of the horizontal petrous ICA exposed was 9.2 +/- 1.0 mm (range, 8.0-11.0 mm). Anterior retraction of V3 provided an additional 4.3 +/- 0.4 mm of carotid exposure (46.7% increase; P < 0.05). The length of the genu was on average 3.6 +/- 0.4 mm (range, 3.0-4.0 mm), and the length of the vertical segment of the petrous ICA was 13.1 +/- 2.0 mm (range, 10.0-15.0 mm). The average depth of the petrous ICA from the outer surface of the temporal bone was 30.6 +/- 1.1 mm (range, 30.0-33.0 mm) at the V3-ICA junction and 27.2 +/- 0.7 mm (range, 26.0-28.0 mm) at the ICA genu. The average diameter of the inner working corridor was 24.2 +/- 3.0 mm (range, 21.5-30.0 mm). Removal of the zygoma increased the outer working corridor from an average distance of 24.4 +/- 3.8 mm to 33.4 +/- 3.4 mm (36.9% increase in exposure; P < 0.05). The average angle of exposure was 66.5% greater (P < 0.05) with zygomatic arch removal (39.3 +/- 4.9 degrees) than without zygomatic arch removal (23.6 +/- 2.7 degrees). CONCLUSION: The transzygomatic extended middle fossa approach provides a wide surgical corridor for maximal exposure of the petrous ICA with minimized temporal lobe retraction. This large exposure facilitates vascular anastomoses at the petrous ICA and provides working room to maneuver instruments. The middle fossa rhomboid is a key landmark to identify the petrous ICA and to avoid neuro-otologic structures.

Anastomosis, Surgical↗
PubMed2006

Progesterone and estrogen receptors: opposing prognostic indicators in meningiomas.

OBJECT: The preponderance of progesterone receptors (PRs) and the scarcity of estrogen receptors (ERs) in meningiomas are well known. The expression of PRs may relate to tumor grade and recurrence. Cytogenetic abnormalities are associated with aggressive behavior, recurrence, and progression. In this study, the authors focus on the prognostic implications of hormone receptors in meningiomas to help determine the clinical and biological aggressiveness of tumors and their correlations with cytogenetic abnormalities. METHODS: Two hundred thirty-nine patients with meningiomas were separated into three groups. Group 1 (PR-positive group) comprised patients whose meningiomas displayed expression of PRs alone. Group 2 (receptor-negative group) included patients whose lesions did not have receptors for either progesterone or estrogen. Group 3 (ER-positive group) included patients whose tumors displayed expression of ERs. Clinical and histological findings, proliferative indices, tumor recurrence, and cytogenetic findings were analyzed by performing the Fisher exact test. Compared with the receptor-negative (Group 2) and ER-positive (Group 3) groups, the PR-positive group (Group 1) had a statistically significant lower proliferative index and a smaller number of patients in whom there were aggressive histopathological findings or changes in karyotype. In Groups 1, 2, and 3, the percentages of cases with aggressive histopathological findings were 10, 31, and 33%, respectively; the percentages of cases with chromosomal abnormalities were 50, 84, and 86%, respectively; and the percentages of cases in which there initially was no residual tumor but recurrence was documented were 5, 30, and 27%, respectively. A statistically significant increase in the involvement of chromosomes 14 and 22 was identified in receptor-negative and ER-positive de novo meningiomas, when compared with the PR-positive group. Abnormalities on chromosome 19 were statistically significantly higher in receptor-negative meningiomas than in PR-positive tumors. CONCLUSIONS: The expression of the PR alone in meningiomas signals a favorable clinical and biological outcome. A lack of receptors or the presence of ERs in meningiomas correlates with an accumulation of qualitative and quantitative karyotype abnormalities, a higher proportional involvement of chromosomes 14 and 22 in de novo tumors, and an increasing potential for aggressive clinical behavior, progression, and recurrence of these lesions. Sex hormone receptor status should routinely be studied for its prognostic value, especially in female patients, and should be taken into account in tumor grading. The initial receptor status of a tumor may change in progression or recurrence of tumor.

Adult↗
PubMed2005

Surgical management of petroclival meningiomas: factors determining the choice of approach.

Petroclival meningiomas remain one of the most challenging intracranial tumors to treat surgically. This is attributable to their location deep within the skull base and their association with multiple critical neural and vascular structures. Over the years, many skull base approaches have been described that are meant to improve resection and decrease patient morbidity. Appropriate selection of the surgical approach requires a thorough preoperative evaluation of clinical and radiological factors. In this paper the authors retrospectively reviewed 97 patients treated surgically for petroclival meningiomas by the senior author (O.A.M.) between 1995 and 2005 to assess the factors used to determine the choice of surgical approach, and to assess complication rates based on the approach selected. The skull base approaches used in these patients included the middle fossa anterior petrosal, posterior petrosal, and combined petrosal approaches, and complete petrosectomy. Factors found to be important in determining the selection of approach included the size, location, and extension of the tumor, preoperative hearing evaluation, and venous sinus anatomy.

Disease Management↗
PubMed2005

Cavernous sinus tumor model in the canine: a simulation model for cavernous sinus tumor surgery.

OBJECTIVE: The recent limitations of working hours for neurosurgical trainees carry the risk of decreasing the amount of microsurgical experience. In the absence of enough surgical exposure to some pathological states, an alternative option of a more continuous source of tactile and visual experience that simulates the real-life state is needed. To help with this problem, we established a cavernous sinus tumor model in the canine. METHODS: A gliosarcoma cell line that was harvested from a tumor model in nude mice was implanted in six mongrel dogs. In the first group (two dogs), the cell line was implanted in the dural leaflets of the cavernous sinus. (Immunosuppression was used in one dog.) In the second group (four dogs), the cell line was implanted in the region of the gasserian ganglion. (Immunosuppression was used in all four dogs.) The condition of each dog was followed through neurological examinations and serial magnetic resonance imaging. The cavernous sinus region later was explored, after which the dogs were later killed and histopathological evaluations of the cavernous sinus region was carried out. RESULTS: The initial cell line implanted within the dural leaflets of the cavernous sinus showed no evidence of tumor growth. The tumor grew in all four dogs that had the gliosarcoma cell line implanted in the region of the gasserian ganglion. The clinical and radiological features as well as the experience of the surgical dissection of these tumors simulated cavernous sinus tumors in humans. CONCLUSION: We established the first cavernous sinus tumor model in the canine. This model simulates the real-life pathological state, and it can be used as an alternative source of surgical experience to advance surgical skills.

Animals↗
PubMed2004

Surgical treatment of dumbbell-shaped jugular foramen schwannomas.

OBJECT: Schwannomas of the jugular foramen are rare, comprising between 2 and 4% of intracranial schwannomas. The authors retrospectively analyzed their surgical experience with schwannomas of the lower cranial nerves that presented with intra- and extracranial extensions through an enlarged jugular foramen. The transcondylar suprajugular approach was used without sacrificing the labyrinth or the integrity of the jugular bulb. In this report the clinical and radiological features are discussed and complications are analyzed. METHODS: This retrospective study includes six patients (three women and three men, mean age 31.6 years) with dumbbell-shaped jugular foramen schwannomas that were surgically treated by the senior author during a 5.5-year period. One patient had undergone previous surgery elsewhere. Glossopharyngeal and vagal nerve deficits were the most common signs (appearing in all patients), followed by hypoglossal and accessory nerve deficits (66.6%). Two or more signs or symptoms were present in every patient. Three tumors presented with cystic degeneration. In four patients the jugular bulb was not patent on neuroimaging studies. The suprajugular approach was used in five patients; the origin of the tumor from the 10th cranial nerve could be defined in three of them. All lesions were completely resected. No death or additional postoperative cranial nerve deficits occurred in this series. Aspiration pneumonia developed in one patient. Preoperative deficits of the ninth and 10th cranial nerves improved in one third of the patients and half recovered mobility of the tongue. No recurrence was discovered during the mean follow-up period of 32.8 months. CONCLUSIONS: With careful, extensive preoperative evaluation and appropriate planning of the surgical approach, dumbbell-shaped jugular foramen schwannomas can be radically and safely resected without creating additional neurological deficits. Furthermore, recovery of function in the affected cranial nerves can be expected.

Accessory Nerve Diseases↗
PubMed2004

The anatomical basis for surgical preservation of temporal muscle.

OBJECT: Mobilizing the temporal muscle is a common neurosurgical maneuver. Unfortunately, the cosmetic and functional complications that arise from postoperative muscular atrophy can be severe. Proper function of the muscle depends on proper innervation, vascularization, muscle tension, and the integrity of muscle fibers. In this study the authors describe the anatomy of the temporal muscle and report technical nuances that can be used to prevent its postoperative atrophy. METHODS: This study was designed to determine the susceptibility of the temporal muscle to injury during common surgical dissection. The authors studied the anatomy of the muscle and its vascularization and innervation in seven cadavers. A zygomatic osteotomy was performed followed by downward mobilization of the temporal muscle by using subperiosteal dissection, which preserved the muscle and allowed a study of its arterial and neural components. The temporal muscle is composed of a main portion and three muscle bundles. The muscle is innervated by the deep temporal nerves, which branch from the anterior division of the mandibular nerve. Blood is supplied through a rich anastomotic connection between the deep temporal arteries (anterior and posterior) on the medial side and the middle temporal artery (a branch of the superficial temporal artery [STA]) on the lateral side. CONCLUSIONS: Based on these anatomical findings, the authors recommend the following steps to preserve the temporal muscle: 1) preserve the STA; 2) prevent injury to the facial branches by using subfascial dissection; 3) use a zygomatic osteotomy to avoid compressing the muscle, arteries, and nerves, and for greater exposure when retracting the muscle; 4) dissect the muscle in subperiosteal retrograde fashion to preserve the deep vessels and nerves; 5) deinsert the muscle to the superior temporal line without cutting the fascia; and 6) reattach the muscle directly to the bone.

Atrophy↗
PubMed2004

Radiation-induced meningiomas: clinical, pathological, cytokinetic, and cytogenetic characteristics.

OBJECT: Radiation-induced meningiomas are known to occur after high- and low-dose cranial radiation therapy. The goal of this study was to discern the distinguishing findings and characteristics of radiation-induced meningiomas. METHODS: The records of 16 patients (seven men and nine women) who fulfilled the criteria for radiation-induced meningiomas were retrospectively reviewed. Clinical, histopathological, cytokinetic, and cytogenetic findings as well as the patients' outcome were analyzed. The mean age of the patients was 38.8 years and the mean tumor latency was 26.5 years. Five patients had multiple meningiomas in the irradiated field. The recurrence rate was 100% after the initial resection; 62% of patients had a second recurrence and 17% had a third recurrence. Thirty-eight percent of patients had atypical or malignant histopathological findings. The presence of progesterone receptors and low proliferation indices in these patients did not correlate with benign tumor behavior. Cytogenetic analysis showed multiple clonal aberrations in all tumors studied. The most frequent aberrations were found on chromosomes 1p, 6q, and 22. Derivative, lost, or additional chromosome 1p was found in 89% of cases and loss or deletion on chromosome 6 was found in 67%. CONCLUSIONS: The age of patients at presentation with meningioma and the latency period of radiation-induced meningiomas are dose related. These tumors are more aggressive and are certain to recur, have a higher histopathological grade, and are associated with complex cytogenetic aberrations particularly involving 1p and 6q.

Adolescent↗
PubMed2004

Malignant progression in meningioma: documentation of a series and analysis of cytogenetic findings.

OBJECT: The malignant progression of benign tumors is well documented in gliomas and other systemic lesions. It is also well known that some meningiomas become progressively aggressive despite their original benign status. The theory of clonal evolution is widely believed to explain malignant progression in meningioma; however, the data used to explain stepwise progression have typically been derived from the cytogenetic analysis of different types of tumors of different grades and in different patients. In this study, the authors examined the data obtained in a group of patients with meningiomas that showed clear histopathological progression toward a higher grade of malignancy and then analyzed the underlying cytogenetic findings. METHODS: Among 175 patients with recurrent meningiomas, 11 tumors showed a histopathological progression toward a higher grade that was associated with an aggressive clinical course. Six tumors progressed to malignancy and five to the atypical category over a period averaging 112 months. Tests for MIB-1 and p53 and cytogenetic studies with the fluorescence in situ hybridization (FISH) method were performed in successive specimens obtained in four patients. The MIB-1 value increased in subsequent samples of tumors. Cytogenetic analysis with FISH showed deletions of 22, 1p, and 14q. In all but one case, these aberrations were also present in the previous specimen despite its lower hispathological grade. CONCLUSIONS: The authors documented the progression of meningiomas from benign to a higher histological grade. These tumors were associated with a complex karyotype that was present ab initio in a histologically lower-grade tumor, contradicting the stepwise clonal evolution model. Although it was limited to the tested probes, the FISH method appears to be more accurate than the standard cytogenetic one in detecting these alterations. Tumors that present with complex genetic alterations, even those with a benign histological grade, are potentially aggressive and require closer follow up.

Adult↗
PubMed2003

Cavernous sinus meningiomas.

Cavernous sinus meningiomas were once considered unresectable. The development of microsurgical and skull base techniques as well as advances in anesthesia and neuroradiology have allowed safe and systematic treatment of these lesions. Proper evaluation and patient counseling are required. A thorough understanding of the anatomy and surgical approaches are crucial to success, as is knowledge of the possible adverse outcomes including cranial neuropathy and stroke. The authors discuss these issues in the treatment of cavernous sinus meningiomas.

Cavernous Sinus↗
PubMed2003

Telomeric fusion as a mechanism for the loss of 1p in meningioma.

Characteristic cytogenetic aberrations are found in the various histopathological designations of meningioma. These aberrations range from the loss of 22q in histologically benign tumors to complex hypodiploid karyotypes in atypical and malignant tumors. This progression is characterized by increasing chromosome loss and instability, with a critical step being the loss of 1p. We report a detailed cytogenetic investigation of chromosome aberrations in a series of 88 meningiomas using Giemsa banding and multicolor spectral karyotyping (SKY). Clonal chromosome aberrations were identified in 46 (52%) tumors by G banding. Thirty-five tumors showing complex chromosome aberrations not fully characterized by G banding were subsequently reanalyzed by SKY. The SKY technique refined the G-band findings in 18 (51%) of the tumors on which it was applied. The most common features of cytogenetic progression in the complex karyotypes were chromosome arm-specific losses relating to the formation of deletions and dicentric chromosomes involving 1p. Part or all of 1p was lost in 19 tumors. Five tumors showed evidence for the loss of 1p in a progressive step-wise series of telomeric fusions involving the formation of unstable intermediates. Five recurring dicentric chromosomes were identified, including dic (1;11)(p11;p11), dic(1;12)(p12 approximately p13;p11), dic(1;22)(p11;q12 approximately q13), dic(7;19)(p11;p11), and dic(19;22)(p11 approximately p13;q11 approximately q13). These findings provide evidence that telomeric fusions play a role in the formation of clonal deletions, dicentrics, and unbalanced translocations of 1p. The loss of 1p has possible diagnostic and prognostic implications in the management of meningioma.

Adult↗
PubMed2003

Fibrous dysplasia of the clivus.

OBJECTIVE: Fibrous dysplasia is a developmental skeletal disorder that may lead to distortion, expansion, and weakening of the bone. Craniofacial involvement by this entity is well recognized and is known to cause neurovascular impingement and cosmetic deformity; fibrous dysplasia of the clivus, however, is unrecognized and seldom reported. Differentiating this entity from more aggressive disease processes affecting the clivus is central for the proper management of lesions in this area. We have studied fibrous dysplasia of the clivus with the goal of depicting its manifestations, outlining its management, and heightening awareness of this disease entity. METHODS: We retrospectively reviewed our database and identified patients with the diagnosis of fibrous dysplasia of the clivus. The demographic data, the clinical and radiological findings, and the management of these patients were reviewed. RESULTS: Eight patients who had experienced fibrous dysplasia of the clivus were identified. They either were asymptomatic (four patients) or presented with headache (four patients). Of the patients who presented with headache, one also had XIIth cranial nerve paralysis and another had dysphagia. The radiological findings for this entity were consistent, with typical findings of hypointensity on T1- and T2-weighted magnetic resonance imaging studies and ground-glass appearance on computed tomographic scans. Four of the patients in our series had pathological confirmation. Treatment was determined by the patient's symptoms. CONCLUSION: Fibrous dysplasia should be considered in the differential diagnosis of lesions affecting the clivus. Its clinical and radiological presentations permit the establishment of the diagnosis. Its management is usually conservative, unless the patient presents with nerve compression or extensive symptomatic involvement of the condyle.

Adult↗
PubMed2003

Recurrence of olfactory groove meningiomas.

OBJECTIVE: Despite apparent gross total resection, olfactory groove meningiomas have a high rate of late recurrence (average, 23%). In this retrospective study, we confirmed that the sites of these recurrences are the cranial base and paranasal sinuses. We postulated that these recurrences stem from conservative handling of the underlying invaded bone. Therefore, we analyzed patient outcomes according to the radicality of surgical resection. METHODS: Fifteen consecutive patients with a diagnosis of olfactory groove meningioma were treated surgically between 1992 and 2001 (nine new cases, six recurrent). Only patients with benign meningiomas were included; atypical and malignant meningiomas were excluded. Surgical resection included the dura and drilling of the underlying bone and resection of involved mucosa. We reviewed each patient's clinical records, radiological studies, sites of recurrence, grade of previous resection, and complications. RESULTS: Olfactory groove meningiomas invaded the underlying bone in 13 cases. All patients with recurrence had previously undergone a surgical resection corresponding only to Simpson Grade 2, which does not include the removal of underlying invaded bone. The sites of recurrence were in the cranial base or adjacent paranasal sinuses. The time to recurrence varied from 1 to 12 years (average, 7 yr; mean, 8 yr). Three patients had undergone one previous resection, two had undergone two previous resections, and one had undergone four previous operations. The ethmoid sinus was involved in all cases of recurrence, either with the sphenoid sinus or with an intracranial recurrence. Thirteen patients underwent complete resection of underlying bone and the invaded paranasal sinuses, then reconstruction of the anterior fossa. No patient died. There were three instances of cerebrospinal fluid leakage (one requiring operative repair), one case of delayed worsening vision after initial improvement, and two cases of transient cranial nerve palsy (Cranial Nerves III and IV). There was no recurrence at follow-up (average, 3.7 yr; range, 1-7.3 yr). CONCLUSION: The cranial base and paranasal sinuses are sites of predilection for recurrence of olfactory groove meningiomas. Recurrence is the result of a direct extension attributable to incomplete resection of involved bone and regrowth at the edge of a previous surgical field. Extensive resection of all suspicious underlying bone is a complement to radical removal of these lesions. Reconstruction with a vascularized pericranial flap to prevent cerebrospinal fluid leakage is crucial.

Adult↗
PubMed2002

Translocation (1;19)(q21;q13.3) is a recurrent reciprocal translocation in meningioma.

Benign meningiomas are characterized by a normal karyotype or loss of all or part of chromosome 22. Histologically higher grade tumors are typically characterized by a pattern of increasing chromosome loss and instability. This characteristic pattern of unbalanced chromosome aberrations is punctuated in the literature by several intriguing reports of a reciprocal t(1;19)(q21;q13.3) as the sole cytogenetic aberration. We report a third case showing the t(1;19)(q21;q13.3) with additional unstable secondary aberrations of a dic(18;22)(p11;p11) and telomeric fusions.

Chromosomes, Human, Pair 1↗
PubMed2002

Comparison of the exposure obtained by endoscope and microscope in the extended trans-sphenoidal approach.

OBJECTIVE: Trans-sphenoidal surgery is often combined with other approaches for the treatment of middle cranial base tumors. By combining a maxillotomy with trans-sphenoidal approach, significantly wider exposure to these regions is gained. However, endoscope-assisted techniques have also been used for sellar and parasellar and upper clival regions. METHODS: An extended trans-sphenoidal approach was performed on 10 cadaver heads using the operating microscope and was repeated with a 0-degree endoscope. The mean horizontal and vertical distances were measured and pictured for each technique, and both distances were compared using a parametric paired Student's t-test. RESULTS: The mean horizontal distances in the 10 specimens were 19.5 +/- 1.8 mm by microscope and 27.5 +/- 2.2 mm by endoscope, and the mean vertical distances were 25.8 +/- 1.9 mm by the microscope and 34.5 +/- 3.5 mm by the endoscope. CONCLUSION: The aim of this study was to quantify the amount of exposure obtained with an extended trans-sphenoidal approach and to compare both endoscopic and microscopic techniques. Using the endoscope in conjunction with the operating microscope may provide additional exposure and better access in skull base surgery.

Journal Article↗
PubMed2002

Trigeminal schwannomas: removal of dumbbell-shaped tumors through the expanded Meckel cave and outcomes of cranial nerve function.

OBJECT: As in patients with vestibular schwannomas, advances in surgical procedures have markedly improved outcomes in patients with trigeminal schwannomas. In this article the authors address the function of cranial nerves in a series of patients with trigeminal schwannomas that were treated with gross-total surgical removal. The authors emphasize a technique they use to remove a dumbbell-shaped tumor through the expanded Meckel cave, and discuss the advantage of the extradural zygomatic middle fossa approach for total removal of tumor and preservation or improvement of cranial nerve function. METHODS: Within an 11-year period (1989-2000), 25 patients (14 female and 11 male patients with a mean age of 44.4 years) with benign trigeminal schwannomas were surgically treated by the senior author (O.A.) with the aim of total removal of the tumor. Three patients had undergone previous surgery elsewhere. Trigeminal nerve dysfunction was present in all but two patients. Abducent nerve paresis was present in 40%. The approach in each patient was selected according to the location and size of the lesion. Nineteen tumors were dumbbell shaped and extended into both middle and posterior fossae. All 25 tumors involved the cavernous sinus. The zygomatic middle fossa approach was particularly useful and was used in 14 patients. The mean follow-up period was 33.12 months. In patients who had not undergone previous surgery, the preoperative trigeminal sensory deficit improved in 44%, facial pain decreased in 73%, and trigeminal motor deficit improved in 80%. Among patients with preoperative abducent nerve paresis, recovery was attained in 63%. Three patients (12%) experienced a persistent new or worse cranial nerve function postoperatively. Fifth nerve sensory deficit persisted in one of these patients, sensory and motor dysfunction in another, and motor trigeminal weakness in the third patient. In all patients a good surgical outcome was achieved. One patient died 2 years after treatment from an unrelated cause. In three patients the tumors recurred after an average of 22.3 months. CONCLUSIONS: Preservation or improvement of cranial nerve function can be achieved through total removal of a trigeminal schwannoma, and skull base approaches are better suited to achieving this goal. The zygomatic middle fossa approach is particularly helpful and safe. It allows extradural tumor removal from the cavernous sinus, the infratemporal fossa, and the posterior fossa through the expanded Meckel cave.

Adolescent↗