Biomedical subjects

Amin Kassam

Publications and source records attributed to Amin Kassam.

At least 19 recordsLinked to original sources

PubMed2006

Clinical and anatomic outcomes after endovascular coiling of middle cerebral artery aneurysms: report on 30 treated aneurysms and review of the literature.

BACKGROUND: Endovascular treatment of middle cerebral artery (MCA) aneurysms has not been extensively studied. We report our experience on a select group of patients that underwent coil embolization of an MCA bifurcation aneurysm. METHODS: From August 1999 to January 2005, 29 patients harboring 30 MCA aneurysms were treated with coil embolization. These patients were felt to have favorable characteristics for endovascular therapy including absence of thrombus in the aneurysm, absence of an efferent artery off of the aneurysm, and ability to reconstruct the wide neck with stent reconstruction. We retrospectively reviewed their records and angiographic images to evaluate for technical result and complications. RESULTS: The mean age of our cohort was 59 +/- 13 years with 19 patients presenting with a ruptured aneurysm. Complete obliteration was achieved in 24 (80%) of 30 of aneurysms on postprocedural angiography and no patient showed aneurysm regrowth at 6-month follow-up. Twenty-seven (93%) of 29 patients had no change in baseline neurological function post-embolization. There were two procedural-related complications: one intraprocedural rupture of an aneurysm and one thromboembolic stroke in the ipsilateral MCA territory. CONCLUSIONS: Coil embolization of MCA bifurcation aneurysms has a high rate of complete obliteration with acceptable morbidity in our selected group of patients.

Aged↗

PubMed2006

Resection of a recurrent paraganglioma via an endoscopic transnasal approach to the jugular fossa.

OBJECTIVE: To present a novel endoscopic, transnasal approach to a recurrent paraganglioma of the jugular fossa (glomus jugulare). STUDY DESIGN: Case report and review of the literature. SETTING: The study was carried out at the University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, U.S.A. PATIENT: A 64-year-old woman presented to the University of Pittsburgh Medical Center with a 9-month history of left otalgia, occasional vertigo, facial pain, and recurrent epistaxis. She had undergone two previous procedures over the past 35 years for a glomus tympanicum. Physical examination revealed a mass in the left nasopharynx originating from the eustachian tube. A computed tomographic scan revealed an expansive mass in the left jugular foramen extending into the posterior parapharyngeal space suggestive of a large jugular paraganglioma. INTERVENTION: The patient underwent preoperative embolization of the paraganglioma. An endoscopic, transnasal approach along the eustachian tube, the ascending parapharyngeal carotid artery, and into the jugular fossa was used to remove the tumor. Intraoperative image guidance assisted in the identification of key anatomic landmarks. RESULTS: Postoperative magnetic resonance imaging revealed a thin rim of enhancement at the posterior aspect of the jugular fossa consistent with residual tumor. The patient was discharged to home on postoperative Day 1 in stable condition. There have been no complications with 4 months of follow-up, and the left facial paralysis secondary to preoperative embolization has resolved. CONCLUSION: We report the successful subtotal resection of a recurrent paraganglioma via a novel endoscopic, transnasal, transclival, transpetrous approach with image guidance. This approach allowed the near-total resection of a recurrent glomus jugulare with minimal surgical morbidity. Technological advances and surgical experience with nasal endoscopy and image guidance allow minimally invasive surgical management of select extracranial lesions of the lateral cranial base.

Embolization, Therapeutic↗

PubMed2006

A novel reconstructive technique after endoscopic expanded endonasal approaches: vascular pedicle nasoseptal flap.

BACKGROUND: In patients with large dural defects of the anterior and ventral skull base after endonasal skull base surgery, there is a significant risk of a postoperative cerebrospinal fluid leak after reconstruction. Reconstruction with vascularized tissue is desirable to facilitate rapid healing, especially in irradiated patients. METHODS: We developed a neurovascular pedicled flap of the nasal septum mucoperiosteum and mucoperichondrium based on the nasoseptal artery, a branch of the posterior septal artery (Hadad-Bassagasteguy flap [HBF]). A retrospective review of patients undergoing endonasal skull base surgery at the University of Rosario, Argentina, and the University of Pittsburgh Medical Center was performed to identify patients who were reconstructed with a vascularized septal mucosal flap. RESULTS: Forty-three patients undergoing endonasal cranial base surgery were repaired with the septal mucosal flap. Two patients with postoperative cerebrospinal fluid leaks (5%) were successfully treated with focal fat grafts. We encountered no infectious or wound complications in this series of patients. One patient experienced a posterior nose bleed from the posterior nasal artery. This was controlled with electrocautery and the flap blood supply was preserved. CONCLUSION: The HBF is a versatile and reliable reconstructive technique for defects of the anterior, middle, clival, and parasellar skull base. Its use has resulted in a sharp decrease in the incidence of postoperative cerebrospinal fluid leaks after endonasal skull base surgery and is recommended for the reconstruction of large dural defects and when postoperative radiation therapy is anticipated.

Adipose Tissue↗

PubMed2006

Magnesium infusion for vasospasm prophylaxis after subarachnoid hemorrhage.

OBJECT: Despite the application of current standard therapies, vasospasm continues to result in death or major disability in patients treated for ruptured aneurysms. The authors investigated the effectiveness of continous MgSO4 infusion for vasospasm prophylaxis. METHODS: Seventy-six adults (mean age 54.6 years; 71% women; 92% Caucasian) were included in this comparative matched-cohort study of patients with aneurysmal subarachnoid hemorrhage on the basis of computed tomography (CT) findings. Thirty-eight patients who received continuous MgSO4 infusion were matched for age, race, sex, treatment option, Fisher grade, and Hunt and Hess grade to 38 historical control individuals who did not receive MgSO4infusion. Twelve grams of MgSO4 in 500 ml normal saline was given intravenously daily for 12 days if the patient presented within 48 hours of aneurysm rupture. Vasospasm was diagnosed on the basis of digital substraction angiography, CT angiography, and transcranial Doppler ultrasonography, and evidence of neurological deterioration. Symptomatic vasospasm was present at a significantly lower frequency in patients who received MgSO4 infusion (18%) compared with patients who did not receive MgSO4 (42%) (p = 0.025). There was no significant difference in mortality rate at discharge (p = 0.328). A trend toward improved outcome as measured by the modifed Rankin Scale (p = 0.084), but not the Glasgow Outcome Scale (p = 1.0), was seen in the MgSO4 treated group. CONCLUSIONS: Analysis of the results suggests that MgSO4 infusion may have a role in cerebral vasospasm prophylaxis if therapy is initiated within 48 hours of aneurysm rupture.

Adolescent↗

PubMed2005

Expanded endonasal approach: the rostrocaudal axis. Part I. Crista galli to the sella turcica.

OBJECT: Transsphenoidal approaches have been used for a century for the resection of pituitary and other sellar tumors. More recently, the standard endonasal approach has been expanded to provide access to other, parasellar lesions. With the addition of the endoscope, this expansion carries significant potential for the resection of skull base lesions. METHODS: The anatomical landmarks and surgical techniques used in expanded (extended) endoscopic approaches to the rostral, anterior skull base are reviewed and presented, accompanied by case illustrations of each segment (or module) of approach. The rostral half of the anterior skull base is divided into modules of approach: sellar/parasellar, transplanum/transtuberculum, and transcribriform. Case illustrations of successful resections of lesions with each module are presented and discussed. CONCLUSIONS: Endoscopic, expanded endonasal approaches to rostral anterior skull base lesions are feasible and hold great potential for decreased morbidity. The effectiveness and appropriate use of these techniques must be evaluated by close examination of outcomes as case series expand.

Cranial Fossa, Posterior↗

PubMed2005

Expanded endonasal approach: the rostrocaudal axis. Part II. Posterior clinoids to the foramen magnum.

OBJECT: Transsphenoidal approaches have been used for a century for the resection of pituitary and other sellar tumors. Recently, however, the standard endonasal approach has been expanded to provide access to other parasellar lesions. With the addition of the endoscope, this expansion has significant potential for the resection of skull base lesions. METHODS: The anatomical landmarks and surgical techniques used in expanded (extended) endoscopic approaches to the clivus and cervicomedullary junction are reviewed and presented, accompanied by case illustrations of each segment (or module) of approach. The caudal portion of the midline anterior skull base and the cervicomedullary junction is divided into modules of approach: the middle third of the clivus, its lower third, and the cervicomedullary junction. Case illustrations of successful resections of lesions via each module of the approach are presented and discussed. CONCLUSIONS: Endoscopic expanded endonasal approaches to caudally located midline anterior skull base and cervicomedullary lesions are feasible and hold great potential for decreased morbidity. The effectiveness and appropriate use of these techniques must be evaluated by close examination of outcomes as case series expand.

Cranial Fossa, Posterior↗

PubMed2005

Endoneurosurgical hemostasis techniques: lessons learned from 400 cases.

The increasing popularity of minimally invasive neurosurgery has led to the development of transnasal expanded approaches for the treatment of skull base lesions. One of the greatest challenges in safely accomplishing resection of tumors, particularly intradural lesions, is effective hemostasis. Over the past 7 years the authors have progressively developed an organized approach to address this challenge. This has required the development of new instrumentation as well as variations on standard techniques. In this report they present the technique that has evolved at their institution for endoneurosurgical hemostasis.

Bone Diseases↗

PubMed2005

Evolution of reconstructive techniques following endoscopic expanded endonasal approaches.

Harvey Cushing first popularized the transsphenoidal route to the sella turcica, and Jules Hardy subsequently refined it by adding the operating microscope. Over the ensuing decades, attempts at extending the application of this approach have been advanced by Edward Laws and others. With the evolution of endoscopic approaches, the natural expansion of their use to intradural lesions followed. For the expanded endonasal approach to become a viable option, the paramount concerns surrounding consistent reconstruction of the dura mater must be overcome. In this review the authors chronicle the evolution of the reconstruction technique they currently use after performing expanded endonasal approaches. They also report the use of a balloon stent to buttress the reconstruction and counter the effects of graft migration and cerebrospinal fluid fistula formation. The technique described in this report represents an important step forward in the reconstruction of defects resulting from expanded endonasal approaches.

Endoscopy↗

PubMed2005

Hyperthermia and hypermetabolism in focal cerebral ischemia.

The reliable and reproducible creation of an animal model of focal cerebral ischemia is not easily accomplished. Using a transortibal approach, we showed that occlusion of the posterior cerebral artery (PCA), middle cerebral artery (MCA), and the contralateral anterior cerebral artery (ACA) created a large cortical and subcortical stroke in the non-human primate (NHP). Subsequently, we created the same stroke endovascularly in the NHP. Using the endovascular stroke model in the NHP, we measured brain temperature with thermocouples and cerebral blood flow (CBF) by stable xenon CT in one NHP, and CMRO2 and CBF by positron emission tomography (PET) in another NHP. Two female non-human primates (M. mulatta) weighing 7.0 and 8.0 kg, respectively, were studied under fentanyl-diazepam anesthesia with continuous monitoring of arterial blood pressure, rectal temperature, and end-tidal CO2 with intermittent blood gas measurements. Using an endovascular approach, the PCA (P2), MCA (M1), and the ICA at the bifurcation and contralateral ACA produced a large hemispheric stroke. In the right ischemic hemisphere, temperatures increased by 2 degrees C-3 degrees C. PET measurement of CBF and CMRO2 showed that CMRO2 increased in the region of the ischemic stroke. We found that both hyperthermia and hypermetabolism occur in acute stroke.

Animals↗

PubMed2005

Sodium MR imaging of acute and subacute stroke for assessment of tissue viability.

Sodium MR imaging at 3.0 T provides high-quality images in acceptable acquisition times that allow assessment of tissue viability as defined by maintenance of sodium ion homeostasis. This application is made feasible for clinical stroke evaluation by an efficient projection pulse sequence with extremely short echo time values. This twisted projection imaging provides high signal-to-noise images at adequate resolution (5 x 5 x 5 mm(3)) in less than 10 minutes at 3.0 T. The images are quantified as tissue sodium concentration (TSC) maps that can be interpreted directly in terms of tissue viability. With infarction, baseline TSC values of less than 45 mmol/L increase at variable rates to approximately 70 mmol/L, allowing monitoring of the progression of stroke pathophysiology.

Adult↗

PubMed2005

Periprocedural morbidity and mortality associated with endovascular treatment of intracranial aneurysms.

BACKGROUND AND PURPOSE: Despite experience and technological improvements, endovascular treatment of intracranial aneurysms still has inherent risks. We evaluated cerebral complications associated with this treatment. METHODS: From October 1998 to October 2002, 180 consecutive patients underwent 131 procedures for 118 ruptured aneurysms and 79 procedures for 72 unruptured aneurysms. We retrospectively reviewed their records and images to evaluate their morbidity and mortality. RESULTS: Thirty-seven (17.6%) procedure-related complications occurred: 27 and six with initial embolization of ruptured and unruptured aneurysms, respectively, and four with re-treatment. Complications included 22 cerebral thromboembolisms, nine intraprocedural aneurysm perforations, two coil migrations, two parent vessel injuries, one postprocedural aneurysm rupture, and one cranial nerve palsy. Fourteen complications had no neurologic consequence. Three caused transient neurologic morbidity; 10, persistent neurologic morbidity; and 10, death. Procedure-related neurologic morbidity and mortality rates, respectively, were as follows: overall, 4.8% and 4.8%; ruptured aneurysms, 5.9% and 7.6%; unruptured aneurysms, 1.4% and 1.4%; and re-treated aneurysms, 10% and 0%. Combined procedure-related morbidity and mortality rates for ruptured, unruptured, and re-treated aneurysms were 13.5%, 2.8%, and 10%, respectively. Nonprocedural complications attributable to subarachnoid hemorrhage in 118 patients with ruptured aneurysm were early rebleeding before coil placement (0.9%), symptomatic vasospasm (5.9%), and shunt-dependent hydrocephalus (5.9%); mortality from complications of subarachnoid hemorrhage itself was 11.9%. CONCLUSION: Procedural morbidity and mortality rates were highest in ruptured aneurysms and lowest in unruptured aneurysms. Morbidity rates were highest in re-treated aneurysms and lowest in unruptured aneurysms. No procedural mortality occurred with re-treated aneurysms. The main cause of morbidity and mortality was thromboembolism.

Adult↗

PubMed2004

Sources of registration error with image guidance systems during endoscopic anterior cranial base surgery.

OBJECTIVES: The goal of this study was to evaluate the accuracy of the registration process and to identify potential sources of error during anterior cranial base surgery. STUDY DESIGN AND SETTING: The registration accuracy of image guidance and the location of excluded fiducials were recorded prospectively from 50 endoscopic, anterior cranial base procedures in an academic university setting. RESULTS: The mean error of initial registration was 2.8 mm (range, 1.4 to 7.1 mm). Following the exclusion of fiducials the mean error of registration was 1.6 mm (range, 0.6 to 3.7 mm). There was a significant improvement in the mean error rate from initial to final registration following the exclusion of fiducials (P < 0.0001). Posterior fiducials were excluded most often and anterior fiducials were excluded the least. Registration accuracy was similar for CT and MRI (P = 0.64). CONCLUSIONS: The accuracy of the Stryker Image Guidance System is enhanced by the exclusion of individual fiducials with high registration errors. SIGNIFICANCE: The exclusion of fiducials with high registration errors increases the accuracy of image guidance in anterior cranial base surgery.

Aged↗

PubMed2004

Giant cell tumor of the skull: a case report and review of the literature.

BACKGROUND: Giant cell tumors are benign lesions that typically occur at the epiphyses of long bones that typically present with pain or swelling. Most data on giant cell tumors in the skull consist of case reports, and many large series of giant cell tumors have no examples in the skull. METHODS: We report a case of giant cell tumor of the skull and review the literature on these lesions. RESULTS: A 24-year-old woman presented with localized tenderness and mild swelling over the left inferior parietal and occipital bones. She was neurologically intact with a nonmobile, tender, palpable mass over the left subocciptal area. A computed tomography (CT) scan showed a radiolucent, expansile, lytic lesion involving the left occipital bone. The patient underwent a left occipital craniectomy with resection of the bone and epidural mass. Permanent histopathologic sections and immunostains revealed a giant cell tumor. CONCLUSIONS: Giant cell tumors are generally benign, locally aggressive lesions for which surgical excision is the treatment of choice. This report contributes to the scarce literature on these tumors in the skull.

Adult↗

PubMed2004

Survey of United States neurosurgical residency program directors.

OBJECTIVE: The field of neurosurgery in the United States faces many challenges. Neurosurgical program directors in the United States represent a logical source for inquiries about manpower issues, the training process, and Residency Review Committee (RRC) oversight. METHODS: Ninety-one active residency program directors were sent an anonymous 31-question survey. The respondents were given the option of adding additional comments. The questions were designed to address issues related to manpower, the training process, and RRC governance. Sixty-one responses were returned before an email reminder and 11 after the reminder (a total response rate of 79%). The data were entered into a database, and a descriptive analysis, with frequency distribution, was performed. RESULTS: The purpose of this review was to gain a preliminary understanding of the perceptions of program directors regarding the neurosurgical training process, the RRC, the oversight process, and projected manpower needs. A 79% response rate is high for a mail survey and likely reflects heightened concern and interest in such issues. The survey responses indicate general satisfaction with the role and governance of the RRC, significantly divergent perceptions of resident output and available positions, and serious concerns regarding the current training process. CONCLUSION: This survey suggests that a broader discussion of resident training issues would be valuable, perhaps using validated survey instruments.

Advisory Committees↗

PubMed2004

Altered arterial homeostasis and cerebral aneurysms: a review of the literature and justification for a search of molecular biomarkers.

DESPITE THE CATASTROPHIC consequence of ruptured intracranial aneurysms, very little is understood regarding their pathogenesis, and there are no reliable predictive markers for identifying at-risk individuals. Given that intracranial aneurysms have a strong but complex genetic component and well-characterized modifiable risk factors, it seems likely that the most valuable approach to developing minimally invasive diagnostic and prognostic tools will involve a multifactorial model that includes both genetic and environmental risk factors. Unfortunately, the genetic basis of intracranial aneurysms is poorly described, and reports describing the association of nonrandom deoxyribonucleic acid sequence variation with intracranial aneurysms have been limited to a handful of ad hoc studies that have focused on a variety of markers in small populations. One reason for this lack of coordinated analysis of the genetic basis of intracranial aneurysms is that the molecular pathogenesis and pathobiological characteristics of the disease are poorly described, so candidate marker selection has been problematic. Few studies have addressed the molecular pathological basis of intracranial aneurysms or the possible mechanisms of intracranial aneurysm formation. In this regard, candidate gene selection strategies have relied almost exclusively on limited knowledge of monogenic disorders such as Ehlers-Danlos syndrome and Marfan's syndrome, in which intracranial aneurysm is a feature of a spectrum of syndromic phenotypes. Without exception, these approaches have not affected the clinical identification and/or management of intracranial aneurysms significantly. Therefore, it is imperative that coordinated large-scale efforts in genetics, molecular biology, and genetic epidemiology are implemented to overcome these obstacles and drive developments in the field. In this review, we summarize the current screening modalities for intracranial aneurysms, review the current state of understanding relating to the genetic basis of intracranial aneurysms, and suggest a broader theory of aneurysm pathogenesis to form the foundation of a coordinated molecular search for biological markers that may be associated with aneurysm formation and rupture.

Cerebral Arteries↗

PubMed2004

Successful management of post-tumor resection middle cerebral artery thrombosis with stent-assisted angioplasty and thrombolytic therapy: case report.

OBJECTIVE AND IMPORTANCE: To describe successful endoluminal revascularization of an acute M1 occlusion 4 days after craniotomy and tumor resection. CLINICAL PRESENTATION: A 16-year-old right-handed girl presented with a 1-month history of daily headaches. The neurological examination was normal. Magnetic resonance imaging and computed tomography demonstrated a mass consistent with an epidermoid tumor compressing the left upper pons, left cerebral peduncle, and mesial left temporal lobe. INTERVENTION: A combination of low-dose antiplatelet agents administered intra-arterially and stent-assisted angioplasty was used. Successful endoluminal revascularization was achieved. Acute complications such as intracranial stent-thrombosis and/or intracranial hemorrhage were successfully avoided. CONCLUSION: In the acute postoperative period, most current chemical thrombolytic protocols are contraindicated because of the prohibitive risk of iatrogenic intracranial hemorrhage. With an understanding of the pharmacokinetics of the currently available antiplatelet drugs, combined chemical and mechanical thrombolysis may be used in the acute postoperative setting for endoluminal recanalization.

Adolescent↗

PubMed2004

Trigeminal neuralgia and glossopharyngeal neuralgia: two orofacial pain syndromes encountered by dentists.

BACKGROUND: Dentists frequently evaluate patients for oropharyngeal pain that may or may not eventually be related to oral pathology. Two rare neurological disorders that present with severe orofacial pain are trigeminal neuralgia, or TN, and glossopharyngeal neuralgia, or GPN. Both are secondary to cranial nerve compression by arteries and veins at the point at which the nerves exit the pons and brainstem. RESULTS: The authors present the results for two series of patients treated for TN and GPN. Significant success can be seen after intracranial microvascular decompression for both disorders, with low complication rates. Short- and long-term outcomes depend on proper patient selection. CLINICAL IMPLICATIONS: It is important for practitioners to recognize these syndromes and properly refer patients to a neurosurgeon experienced in treating such disorders. This can help the dentist and patient avoid oral procedures that will not alleviate the painful symptoms.

Anticonvulsants↗

PubMed2004

Effects of Tisseel fibrin glue on the central nervous system of nonhuman primates.

For many years, neurosurgeons and otolaryngologic surgeons have used the fibrin glue product Tisseel to repair skull-base spinal fluid leaks and to help secure repairs following anterior cranial-base surgery. Despite the widespread use, the potential focal cerebral toxicity of this fibrin glue has never been investigated. We studied the safety of Tisseel applied directly to neural tissue (brain parenchyma, cervical cord, and C3-C6 spinal roots) of 6 monkeys (Macaca nemestrina) to determine if any underlying biochemical injury would occur. Another 3 animals that served as controls received saline rather than Tisseel. We found that median nerve electroencephalographic tracings and somatosensory evoked potentials in the experimental and control animals were identical. Likewise, cerebrospinal fluid indicators of neuronal or brain injury, inflammatory responses, and infection were negative in both groups. Finally, there were no significant differences between the two groups with respect to edema volumes and apparent diffusion coefficient values. We conclude that Tisseel does not induce an apparent inflammatory response or abnormal neurophysiologic or histologic response within 5 days of its application when it is applied directly to the brain parenchyma or onto the cervical spinal cord.

Animal Experimentation↗