Biomedical subjects
Publications and source records attributed to A G Vishteh.
A case of a cavernous malformation of the pineal region is reported. Unique magnetic resonance images of a histologically-verified cavernous malformation of the pineal region are presented and the relevant literature on the subject is reviewed.
OBJECTIVE: Lesions situated posterolaterally along the mesencephalon present neurosurgeons with a special challenge. The midline and paramedian variations of the supracerebellar infratentorial approaches do not adequately expose this region. The subtemporal approach risks injury to the vein of Labbé. An extreme lateral supracerebellar infratentorial approach with more radical resection of bone superiorly and laterally, and skeletonization of the sigmoid and transverse sinuses, was used to approach lesions at this location in eight METHODS: Five cavernous malformations, two juvenile pilocytic astrocytomas, and one peripheral superior cerebellar artery aneurysm located in this region were approached in eight patients. In this extreme lateral approach, the sigmoid sinus is unroofed more superiorly and the bone flap includes not only a posterior fossa craniotomy but also a portion that extends just above the transverse sinus. The dural opening is based along the transverse and sigmoid sinuses. After the cerebrospinal fluid has been drained, the lateral aspect of the brainstem is approached via the cerebellar surface. A proximal tentorial incision offers additional rostral exposure where needed. RESULTS: Seven patients in this series underwent successful resection of their lesion. The remaining patient's aneurysm was clipped successfully with no major complications. CONCLUSION: The extreme lateral supracerebellar infratentorial approach differs from the midline and paramedian supracerebellar infratentorial variants in the area of exposure, patient positioning, and location of the craniotomy. The technique is effective for approaching the posterolateral mesencephalon.
The microsurgical anatomy of the temporal and zygomatic branches of the facial nerve are presented along with related local vasculature (frontal and parietal branches of the superficial temporal artery [STA]) as encountered when using subfascial and submuscular temporal muscle dissection techniques for anterolateral craniotomies. Twenty sides were studied in 10 cadaveric specimens that had been previously injected with latex. The rami of the temporal and zygomatic branches of the facial nerve and branches of the STA were dissected out through pterional and orbitozygomatic approaches by using a submuscular or subfascial temporal muscle dissection technique. The three rami of the temporal branch of the facial nerve (the auricularis, frontalis, and orbicularis) were found to run within the galeal plane of the scalp. The zygomatic branch of the facial nerve was found to course deeper than the most caudal extension of the galea, known as the superficial musculoaponeurotic layer. The frontal branch of the STA served as an important landmark for the subfascial or submuscular dissections because excessive reflection of the scalp flap inferior to the level of this vessel would inadvertently injure the frontalis branch of the facial nerve. Subfascial and submuscular dissections of the temporal muscle offer an alternative to the interfascial technique during anterolateral craniotomies. Scalp and temporal dissection performed with careful attention to anatomical landmarks (frontal branch of the STA and the suprafascial fat pad) provides a safe and expeditious alternative to the traditional interfascial technique.
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OBJECTIVE: To determine the prevalence of multiple neuraxis cavernous malformations in patients who initially presented with intramedullary spinal cord (IMSC) cavernous malformations without knowledge of cavernous malformations elsewhere in the neuraxis. METHODS: Hospital records and radiographic files were analyzed for 17 patients who subsequently underwent surgical resection of an IMSC cavernous malformation (histologically proven) and also underwent brain magnetic resonance imaging studies. These 17 patients represented a subset of 32 patients who underwent surgical resection of an IMSC cavernous malformation during the same period. RESULTS: Of 17 patients, 8 (47%) harbored multiple cavernous malformations. This group was composed of five women and three men (mean age, 35.9 yr). There were four Caucasian and four Hispanic patients. CONCLUSION: The prevalence of multiple cavernous malformations in the neuraxis seems to be increased in patients who harbor IMSC cavernous malformations. This finding has important implications for the evaluation and management of these patients and, in some cases, their family members.
OBJECTIVE: Rhinocerebral mucormycosis is a clinical syndrome resulting from an opportunistic infection caused by a fungus of the order Mucorales. The prognosis of rhinocerebral mucormycosis, once considered uniformly fatal, remains poor. Even with early diagnosis and aggressive surgical and medical therapy, the mortality rate is high. We present a patient with rhinocerebral mucormycosis involving the paranasal sinuses and cranial base who experienced long-term survival after multimodality treatment. Clinical characteristics of the disease are discussed, and the literature is reviewed. CLINICAL PRESENTATION: A 24-year-old diabetic man presented with invasive rhinocerebral mucormycosis involving the paranasal sinuses, right middle fossa, and right cavernous sinus. INTERVENTION: The patient underwent endovascular sacrifice of the involved carotid artery and radical resection of the cranial base, including exenteration of the cavernous sinus. Reconstruction with a local muscle flap was performed. He continued to receive intravenous and intrathecal administration of antibiotics. CONCLUSION: Long-term survival with invasive rhinocerebral mucormycosis is rare, but possible, with aggressive multimodality treatment, including carotid sacrifice for en bloc resection of the pathology, when indicated.
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OBJECT: This study was undertaken to evaluate the long-term angiographic outcome of surgically treated aneurysms, which is unknown. Specifically, the incidence of recurrent aneurysms, the fate of residual necks, and the de novo formation of aneurysms were evaluated. METHODS: One hundred two patients (80 females and 22 males; mean age 49 years; range 12-78 years) harboring a total of 167 aneurysms underwent late follow-up angiography; 160 aneurysms were surgically treated. Late angiographic follow-up review was obtained at a mean of 4.4 +/- 1.6 years postsurgery (range 2.6-9.7 years). Late follow-up angiography revealed two recurrent aneurysms (1.5%) of 135 clipped aneurysms without residua. Of 12 aneurysms with known residua, there were eight "dog-ear" residua, of which two (25%) enlarged. One hemorrhage was noted, yielding a hemorrhage risk of 1.9% per year. A second subgroup with broad-based residua revealed dramatic regrowth in three of four cases. Eight de novo aneurysms were found in six patients, for an annual risk of 1.8% per year. A history of multiple aneurysms was associated with de novo aneurysm formation (p = 0.049, chi-square analysis). CONCLUSIONS: This study confirms the long-term efficacy of aneurysm clip ligation. In addition, the authors found there is a small but significant risk of de novo aneurysm formation, particularly in patients with multiple aneurysms. Most residual aneurysm rests appear to remain stable, although a subset may enlarge or rupture. These findings support the rationale for late angiographic follow-up review in patients with aneurysms.
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OBJECT: The use of intraoperative angiography of the spine has become available to neurosurgeons as an adjunct in the management of complex spinal vascular malformations. These vascular malformations are rare, and the use of intraoperative angiography of the spine has not been well described. The authors report their recent experience with the use of this diagnostic modality. METHODS: Between 1995 and 1997, nine consecutive patients with type II or Type IV spinal arteriovenous malformations (AVMs) underwent intraoperative spinal angiography. The cervical spine was involved in three patients, the thoracic spine in five, and the thoracolumbar junction in one. In three patients, intraoperative spinal angiography revealed an unexpected finding (residual filling of the AVM). The results obtained using postoperative spinal angiography in all patients showed complete agreement with the intraoperative studies. No complications arose from obtaining the intraoperative spinal angiograms. CONCLUSIONS: Intraoperative spinal angiography is technically feasible, can be performed safely, and has adequate resolution. It detects unexpected residual AVM in one-third of cases.
OBJECT: The authors sought to determine the biomechanics of the occipitoatlantal (occiput [Oc]-C1) and atlantoaxial (C1-2) motion segments after unilateral gradient condylectomy. METHODS: Six human cadaveric specimens (skull with attached upper cervical spine) underwent nondestructive biomechanical testing (physiological loads) during flexion-extension, lateral bending, and axial rotation. Axial translation from tension to compression was also studied across Oc-C2. Each specimen served as its own control and underwent baseline testing in the intact state. The specimens were then tested after progressive unilateral condylectomy (25% resection until completion), which was performed using frameless stereotactic guidance. At Oc-C1 for all motions that were tested, mobility increased significantly compared to baseline after a 50% condylectomy. Flexion-extension, lateral bending, and axial rotation increased 15.3%, 40.8%, and 28.1%, respectively. At C1-2, hypermobility during flexion-extension occurred after a 25% condylectomy, during axial rotation after 75% condylectomy, and during lateral bending after a 100% condylectomy. CONCLUSIONS: Resection of 50% or more of the occipital condyle produces statistically significant hypermobility at Oc-C1. After a 75% resection, the biomechanics of the Oc-C1 and C1-2 motion segments change considerably. Performing fusion of the craniovertebral junction should therefore be considered if half or more of one occipital condyle is resected.
Transoral approaches are used to expose the craniovertebral junction anteriorly. In patients in whom there is limited mandibular excursion, the placement of retractors and/or surgical instruments is difficult, and midline "stairstep split mandibulotomy" has been advocated as an adjunctive procedure. Although effective, this approach requires external splitting of the lip as well as median glossotomy or a lateral mucosal incision. The purpose of this study was to show that bilateral sagittal split mandibular osteotomies (BSSMOs), which are used in orthognathic surgery, represent a safer and more effective alternative to the stairstep split mandibulotomy when performed as an adjunct to the transoral approach because all incisions are intraoral and the plane of retraction is rostrocaudal instead of lateral. Hospital records and radiographic files of four patients who underwent BSSMO/transoral approach for odontoidectomy between 1994 and 1997 were reviewed retrospectively. There were three women and one boy (mean age 37.8 years, range 11-68 years). Predisposing conditions included rheumatoid arthritis (two patients), Klippel-Feil syndrome (one patient), and congenital occipitocervical instability (one patient). Jaw mobility was limited in all patients. In addition, one patient had macroglossia, another micrognathia, and another retrognathia. The BSSMO provided excellent exposure for resection of the odontoid process, as verified on follow-up magnetic resonance imaging or computerized tomography studies obtained in all patients. All mandibles were rigidly fixed by placing anterior mandibular border titanium plates and unicortical screws, and there was no incidence of nonunion or of lingual or inferior alveolar nerve injuries. The mean follow-up period was 26 months. The BSSMO is an excellent, less invasive adjunct to the transoral approach in patients with limited jaw mobility.
The authors detail a rare case of basilar artery thrombosis in a patient with traumatic cervical spine facet dislocation. Although the patient's deficits could initially be explained by the spinal injury, deterioration to a "locked-in-state" could not. In addition to vertebral artery injuries, the basilar artery can also be indirectly involved in cases of cervical spine trauma. In the rare viable patient, immediate reduction of cervical spine dislocation may allow endovascular thrombolysis, if not otherwise contraindicated.
UNLABELLED: OBJECTIVES AND IMPORTANCE: Although controversial, revascularization of the distal posterior cerebral artery (PCA) may become necessary in treating complex PCA aneurysms before proximal parent vessel sacrifice. The revascularization of the distal PCA territories of two patients with peripheral PCA aneurysms is presented. CLINICAL PRESENTATIONS: One patient had an aneurysm of the P2-P3 segment and failed a selective P2 balloon occlusion test by developing homonymous hemianopia before planned parent vessel sacrifice. The other patient with a giant P2 segment aneurysm presented with visual field deficits. TECHNIQUE: The distal segment of PCA was revascularized before the aneurysms were trapped by surgical clipping or coil occlusion of the distal P2 segment, proximal to the aneurysms. In both cases, the occipital artery was used as the "donor" vessel. Temporary occlusion times were 22 and 20 minutes, respectively. Both grafts were patent on postoperative angiography, and both patients had full visual fields at the time of their follow-up examinations. CONCLUSION: De novo distal P2 sacrifice, advocated for treating peripheral PCA aneurysms, leads to visual field deficits in some patients. Revascularization of the distal segment of the PCA, less technically demanding than bypass to other PCA segments, preserves blood flow, thus sparing vision in this subset of patients.
INTRODUCTION: Surgical management of traumatic internal carotid artery (ICA) dissection remains controversial. Therefore, the delayed outcomes and graft patency rates of patients who underwent bypass procedures for symptomatic traumatic ICA dissection were studied. METHODS: Between September 1989 and August 1996, 13 patients (9 male and 4 female patients; mean age, 30.6 yr) underwent 16 revascularization procedures for symptomatic traumatic ICA dissection. The duration of clinical follow-up averaged 47.3 months (range, 12-94 mo) from the date of diagnosis. The duration of radiographic follow-up (catheter or magnetic resonance angiography, duplex Doppler ultrasonography) averaged 24 months (range, 12-60 mo). RESULTS: ICA dissection was caused by blunt (n = 11) or penetrating trauma (n = 2). Associated angiographic abnormalities included seven ipsilateral ICA occlusions, six dissecting aneurysms, two carotid-cavernous fistulae, and six contralateral traumatic ICA dissections. Patients requiring early revascularization (n = 6) underwent bypass procedures an average of 19.2 days after their injuries. Medically managed patients who developed ischemia later were revascularized a mean of 7.8 months after injury. The mean Glasgow Coma Scale score at the time of presentation was 10 (range, scores of 6-15), and the mean Glasgow Coma Scale score before revascularization was 14 (range, scores of 9-15). There were 14 saphenous vein ICA bypasses (8 cervical-to-petrous, 3 cervical-to-middle cerebral artery, 3 petrous-to-supraclinoid) and 2 superficial temporal artery-to-middle cerebral artery bypasses. There was one early postoperative graft occlusion, which responded to surgical thrombectomy. One patient with multiple other traumatic injuries died as a result of a pulmonary embolus 12 months after revascularization. All remaining patients had Glasgow Outcome Scale scores of 5, with patent bypass grafts confirmed during follow-up. CONCLUSION: Revascularization for persistently symptomatic traumatic ICA dissection eliminated ischemia and was associated with excellent long-term outcomes and graft patency rates.