Direct surgery of basilar trunk and vertebrobasilar junction aneurysms via the combined transpetrosal approach.
Surgical access to aneurysms of the basilar trunk and vertebrobasilar junction is hampered by their direct proximity of these lesions to highly vulnerable neural structures like the brain stem and cranial nerves, as well by the bony structure of the petrous bone blocking the direct surgical approach to these aneurysms. Only recently lateral approaches directed through parts of the petrous bone have been reported for surgery of basilar trunk and vertebrobasilar junction aneurysms like the anterior transpetrosal, the retrolabyrinthine transsigmoid, as well as the combined supra-infratentorial posterior transpetrosal approach. As experience in the use of this approach is limited in the neurosurgical literature we present our surgical experiences in 11 patients with basilar trunk and vertebrobasilar junction aneurysms, operated on using the supra-infratentorial posterior transpetrosal approach. In 10 patients, including one patient with a giant partially thrombosed basilar trunk aneurysm, direct clipping of the aneurysm via the transpetrosal route was possible. In one patient with a giant vertebrobasilar junction aneurysm, the completely calcified aneurysm sac was resected after occlusion of the vertebral artery. Of the whole series, one patient died and in three patients postoperative accentuation of preexisting cranial nerve deficits occurred. Except transient cerebrospinal fluid leak in two patients, the postoperative course was uneventful in the remaining patients. Postoperative angiography demonstrated complete aneurysm clipping in ten patients and relief of preoperative brain stem compression in the patient with the giant vertebrobasilar junction aneurysm. It is concluded, that the supra-infratentorial posterior transpetrosal approach allows excellent access to the basilar artery trunk and vertebrobasilar junction and can be considered the approach of choice to selected aneurysms located in this area. (+info)
Multichannel fenestrations of the petrous segment of the internal carotid artery.
Multichannel fenestration of the internal carotid artery (ICA) is a rare, previously unreported developmental anomaly with unknown clinical significance. Although previously thought to have distinct embryologic origins, the presence of multiple channels in a short-segment fenestration favors a common developmental pathway for the origin of duplications and fenestrations: the persistence of a plexiform vascular network from the 4-mm to 5-mm embryologic stage of development. (+info)
Low-dose high-resolution CT of the petrous bone.
PURPOSE: To show that CT of the petrous bone can be realized using a low-dose technique. MATERIAL: and methods: A high-contrast phantom was scanned with 1.5 mm slice thickness and 60-510 mAs using the reconstruction algorithms standard, bone and edge. In 50 patients, the petrous bone was examined using the standard protocol at 510 mAS. Additionally, selected slices were made at 120 or 210 mAs. The resolution of relevant structures was compared. Phantom studies were repeated on a second CT-device; images of patients scanned with 80 mAs were analyzed in regard to resolution of osseous details. RESULTS: With the first CT-device structures of the phantom up to 0. 5 mm were depicted using 510 mAs and the edge kernel. With 120 mAs and the bone kernel structures of 0.6 mm could be distinguished. Although the same resolution was achieved with 60 mAs and the edge kernel, patient examinations showed a profound image noise. The results achieved with 120 mAs and the bone algorithm, however, were equal to that of 510 mAs. With the second device the same image quality was realized with only 80 mAs. CONCLUSION: CT-examinations of the petrous bone can be effected without loss of diagnostic information using only 15% of the radiation dose used for a standard brain examination. (+info)
Direct clipping of a large basilar trunk aneurysm via the posterior petrosal (extended retrolabyrinthine presigmoid) approach--case report.
A 53-year-old female presented with an unruptured, large basilar trunk aneurysm manifesting only as headache with no neurological deficits, including absence of cranial nerve dysfunction. Cerebral angiography disclosed a large aneurysm with a wide neck arising from the midbasilar artery. We treated the aneurysm surgically via the posterior petrosal approach. Five angled clips were applied sequentially to the aneurysm and the basilar artery was successfully reconstructed. Electrophysiological monitoring was continued during the operation and showed no changes. Following the operation, the patient suffered from transient right abducens nerve palsy, which persisted for 3 months. Postoperative angiography showed that the aneurysm was obliterated, and the patency of the basilar artery was preserved. (+info)
Petrous apex cephaloceles.
BACKGROUND AND PURPOSE: Petrous apex cephaloceles (PACs) are uncommon lesions that are usually incidental but may be symptomatic. We reviewed MR and CT studies in 10 patients with PACs to identify characteristic imaging features that facilitate their diagnosis. METHODS: MR and CT studies from 10 patients with PACs were reviewed retrospectively. In each case the PAC was characterized by lesion center, signal intensity or attenuation, adjacent petrous apex pneumatization, and its relationship to Meckel's cave. Intraoperative findings were reviewed in the three cases in which surgery was performed. RESULTS: All 10 patients had lobulated expansile cystic petrous apex lesions centered along the posterolateral margin of Meckel's cave. All cysts were contiguous with Meckel's cave. Three patients had bilateral PACs. Four patients had symptoms that could potentially be explained by the PAC, while findings in the other six were incidental observations. Three patients underwent surgery, during which two lesions were diagnosed as meningoceles while the third was diagnosed as an arachnoid cyst protruding through a dural defect. CONCLUSION: PACs represent a protrusion of meninges and CSF from the posterolateral portion of Meckel's cave into the petrous apex, which is their characteristic imaging appearance. PACs are usually incidental but may be symptomatic. Surgical intervention should be approached cautiously and undertaken only when symptoms are clearly linked to the presence of this lesion. (+info)
Isolated abducens nerve paresis associated with incomplete Horner's syndrome caused by petrous apex fracture--case report and anatomical study.
A 17-year-old male presented with a wound on the right temporal region, oozing hemorrhagic necrotic brain tissue and cerebrospinal fluid, following a fall. Computed tomography showed temporoparietal and petrous apex fractures on the right. Neurological examination revealed abducens nerve paresis, ptosis, and myosis on the right side. The patient was treated surgically for the removal of the free bony fragments at the fracture site and to close the dural tear. The abducens nerve paresis, ptosis, and myosis persisted at the 3rd monthly postoperative follow-up examination. The anatomy of the abducens nerve at the petroclival region was studied in four cadaveric heads. Two silicone-injected heads were used for microsurgical dissections and two for histological sections. The abducens nerve has three different angulations in the petroclival region, located at the dural entrance porus, the petrous apex, and the lateral wall of the cavernous segment of the internal carotid artery. The abducens nerve had fine anastomoses with the trigeminal nerve and the periarterial sympathetic plexus. There were fibrous connections extending inside the venous space of the petroclival area. The abducens nerve seems to be vulnerable to damage in the petroclival region, either directly by trauma to its dural porus and petrous apex or indirectly by stretching of the nerve through the nervous and/or fibrous connections. Concurrent functional loss of the abducens nerve and the periarterial sympathetic plexus clinically manifested as incomplete Horner's syndrome in our patient. (+info)
Large giant cell reparative granuloma of the petrous bone--case report.
A 41-year-old man presented with a large mass bulging over the suprazygomatic temporal region. Neuroradiological examination showed that the huge extra-axial mass with osteolytic character originated from the upper surface of the petrous bone. Preoperative obliteration of the feeding arteries with super-selective intravascular embolization was helpful for the total removal of the tumor. Histological examination revealed that the tumor consisted of massive fibrohistiocytic proliferation with numerous heavily hemosiderin-laden macrophages and numerous multinucleated giant cells. The most probable diagnosis was giant cell reparative granuloma. Therefore, no postoperative irradiation or other adjuvant therapy was given. (+info)
Anterior transpetrosal approach for pontine cavernous angioma--case report.
A 58-year-old male patient presented with headache and unsteady gait. Magnetic resonance imaging revealed hemorrhage from a pontine cavernous angioma. The patient experienced stepwise aggravation of symptoms due to repeated hemorrhages. We decided to surgically remove the pontine cavernous angioma through an anterior transpetrosal approach, since the angioma and hematoma were located near the ventrolateral surface of the pons. The brain stem was incised at a site caudal to the trigeminal nerve and the hematoma and angioma were totally removed. No additional neurological deficits were observed following surgery. Brain stem cavernous angiomas are usually removed via a trans-fourth ventricle or lateral suboccipital approach. However, these approaches may not be appropriate if the angioma is located ventrally to the pons. We propose that the anterior transpetrosal approach is the method of choice for ventrally located pontine cavernous angioma. (+info)