Mustafa K. Başkaya

An alternative extradural exposure to the anterior clinoid process: the superior orbital fissure as a surgical corridor.

OBJECTIVEDolenc has pioneered the extradural approach to the anterior clinoid process (ACP) in approaching the cavernous sinus, clinoidal space, and orbital apex. A key step is the division of the frontotemporal dural fold (FTDF). Less experienced surgeons may not be as versatile in their three-dimensional understanding of the superior orbital fissure and thus may risk injury to its contents. Through our cadaveric and subsequent clinical experience, we have devised a modification of the approach that permits safer handling of the contents of the superior orbital fissure. METHODSIn five consecutive injected cadaveric heads (10 sides), we performed on one side a traditional extradural exposure of the ACP. On the other side, we performed our alternative dissection. Instead of exposing the ACP from medial to lateral and dividing the frontotemporal dural fold along the assumed path of safety, we followed the edge of the lesser wing from lateral to medial, uncovered the superior orbital fissure, and peeled the outer layer of the cavernous sinus medial to the foramen rotundum along the greater wing, thus uncovering the inferolateral surface of the ACP. This allowed dural division under full visualization. RESULTSThe alternative method proved easier and more reliable in every case. We applied this technical modification in seven patients with no complications. Specifically, there was no injury to the oculomotor, lacrimal, frontal, or trigeminal nerves or branches. We present detailed anatomic expositions of the injected specimens. CONCLUSIONThis technical modification of the extradural approach of Dolenc is a simple, safe, and valuable adjunct to the exposure of the ACP. We recommend its use particularly by relatively inexperienced surgeons.

Minimally invasive cervical expansile laminoplasty: an initial cadaveric study.

OBJECTIVEExpansile laminoplasty has been successfully used to treat cervical myelopathy attributable to canal stenosis. However, detachment of the posterior cervical muscles is thought to contribute to postoperative axial neck pain and kyphosis. Minimizing the amount of muscular dissection might reduce the likelihood of these sequelae. METHODSSix human cadaveric spines were used to assess the feasibility of a minimally invasive laminoplasty technique. A 22-mm tubular dilator port was used to access the lamina-facet junctions from C2 to C7, through bilateral stab incisions at C4–C5 and C5–C6. Troughs at the lamina-facet junctions were drilled bilaterally, and the contiguous laminae were lifted en bloc from one side. Ten-millimeter rib allograft spacers were inserted to maintain a gap on the open side. RESULTSExposure of six cervical levels was easily accomplished with two small incisions on each side. Drilling was achieved without dural violations. The midsagittal spinal canal diameter was increased by a mean of 38% and the spinal canal area was increased by an average of 43% at the level of C5. CONCLUSIONA minimally invasive approach for cervical laminoplasty could be performed in human cadavers. The measured increases in spinal canal space approximated those demonstrated to be associated with stabilization or improvement of neurological status.

Penetration of the optic nerve by an internal carotid artery-ophthalmic artery aneurysm: case report and literature review.

OBJECTIVE AND IMPORTANCEAlthough it is well known that large or giant internal carotid artery-ophthalmic artery aneurysms can cause visual deficits, penetration and schism of the optic nerve by an aneurysm are very rare. CLINICAL PRESENTATIONA 48-year-old man presented with an acute onset of right visual deterioration after an episode of severe headache. Magnetic resonance imaging demonstrated penetration of the right optic nerve by an intracranial aneurysm. Cerebral angiography revealed an internal carotid artery-ophthalmic artery aneurysm of 12 × 7 mm. The aneurysm was directed superomedially and appeared to have a “waist” within the penetration. INTERVENTIONIntraoperatively, we observed that part of the aneurysm wall was visible through the optic nerve fibers at the junction with the optic chiasm. CONCLUSIONAlthough there was no direct evidence of subarachnoid hemorrhage on imaging scans or with operative exploration, we think that the patient must have experienced sentinel hemorrhaging, leading to visual deterioration. We describe the case in detail and review the world literature.

Cerebral arteriovenous malformations.

Arteriovenous malformations (AVMs) are vascular abnormalities consisting of fistulous connections of arteries and veins without a normal intervening capillary bed. In the cerebral hemispheres, they frequently occur as cone-shaped lesions with the apex of the cone reaching toward the ventricles. Nearly all AVMs are thought to be congenital. Supratentorial location is the most common (90%). The most common presentation of an AVM is intracerebral hemorrhage (ICH). After ICH, seizure is the second most common presentation. Other presentations of AVMs include headache and focal neurological deficits, which may be related to steal phenomena or other alteration in perfusion in the tissue adjacent to the AVM, such as venous hypertension from arterialization of normal draining veins. In managing unruptured AVMs, it is important to understand the natural history of these vascular malformations. The decision for no treatment or for a single modality or multimodality treatment paradigm also involves being familiar with the outcomes and risks of each treatment modality—microvascular resection, endovascular embolization, and stereotactic radiosurgery. Finally, the patient-related factors, such as age, general medical condition, neurological condition, occupation, and lifestyle must also be taken into consideration before reaching a conclusion. The treatment of AVMs is highly individualized. There is no universal algorithm or protocol to be followed when dealing with these unique problems. The currently used treatments for AVMs include microsurgical resection only, preoperative endovascular embolization followed by microsurgical resection, stereotactic radiosurgery only, preprocedural endovascular embolization followed by radiosurgical treatment, endovascular embolization only, and observation only. The ultimate goal for all of these modalities is cure for the patient; however, the only way to achieve cure is with complete obliteration of the AVM. Microsurgical resection, whenever it can be perfromed safely is the “gold standard” treatment for brain AVMs, and other methods of treatment must be measured against it. There is certainly a well-established role for adjunctive endovascular embolization of some AVMs. Clearly, there are specific situations, such as small deep AVMs in eloquent brain structures, in which microsurgery should not be used as the primary treatment modality; stereotactic radiosurgery and occasionally embolization (if there is reasonable expectation of complete obliteration by embolization) are the preferred treatment options in these cases. We also make a case for observation in patients with large AVMs in or near critical areas of the brain that are not ideal for surgical resection or radiosurgery. Here, the pursuit of treatment may actually be more harmful to the patient than the natural history of the AVM.

Aneurysm of the anterior inferior cerebellar artery-posterior inferior cerebellar artery variant: Case report with anatomical description in the cadaver

OBJECTIVE AND IMPORTANCE: The authors report a very rare case of an aneurysm at the distal segment of the anterior inferior cerebellar artery-posterior inferior cerebellar artery (AICA-PICA) variant along with a description of the surgical anatomy of this variation in a cadaveric specimen. CLINICAL PRESENTATION: A 44-year-old woman experienced the sudden onset of severe headache and vomiting. Computed tomographic scanning revealed subarachnoid and intraventricular hemorrhage. Cerebral angiography demonstrated a saccular aneurysm arising from the tonsillomedullary segment of the right PICA and a second aneurysm arising from the cortical segment of the common trunk of an AICA-PICA variation. INTERVENTION: Via bilateral suboccipital craniotomy, both aneurysms were clipped. CONCLUSION: Only two cases of aneurysms arising from an AICA-PICA variation have been reported in the literature and no detailed description of the surgical anatomy of this variation has been carried out in previous publications. To our knowledge, the present report is the first description of a clinical case along with a detailed surgical anatomic study in a cadaver.

Persistent primitive hypoglossal artery with retrograde flow from the vertebrobasilar system: A case report

The persistent primitive hypoglossal artery (PPHA) is one of the pairs of arterial connections that exist in the human embryo between the developing anterior and posterior circulation. Normally the PPHA arises from the cervical internal carotid artery (ICA) and passes through the hypoglossal canal to join the caudal basilar artery (BA). In most cases the vertebral arteries (VA) are either hypoplastic or aplastic and the posterior communicating arteries (PComA) are absent; thus, the main supply to the posterior circulation comes from the internal carotid via the PPHA in an antegrade fashion. Atherosclerotic plaques in the ICA and PPHA present with ischemic symptoms of both the carotid and vertebrobasilar systems. We report a case of a 53-year-old female who presented with a transient episode of left lower extremity numbness and weakness. Work-up with computed tomography (CT) and magnetic resonance imaging (MRI) showed a small watershed infarct in the right middle cerebral artery (MCA)/posterior cerebral artery (PCA) territory. Diagnostic angiography revealed severe proximal stenosis of the cervical ICA and presence of a PPHA just above the stenosis with retrograde filling from the vertebrobasilar junction to the distal cervical ICA. The patient underwent a carotid endarterectomy with intraoperative EEG monitoring. Intraoperative blood flow measurements were made before and after endarterectomy showing evidence of reversal of blood flow to a normal antegrade fashion. The postoperative angiogram showed resolution of the right ICA stenosis and persistence of the PHA. To our knowledge this is the first case report of a PPHA exhibiting reversal of blood flow from the posterior into the anterior circulation. Awareness of this embryological anomaly and its interaction with acquired atherosclerotic disease will minimize misinterpretation of vascular diagnostic studies.

Effect of difluoromethylornithine on reperfusion injury after temporary middle cerebral artery occlusion

Polyamines have been shown to play an important role in the disturbance of the blood-brain barrier (BBB) in a number of pathological states including ischemia. BBB disturbances may be almost completely prevented by treating animals with the ornithine decarboxylase (ODC) inhibitor, alpha-difluoromethylornithine (DFMO). DFMO has been also shown to prevent N-Methyl-D-aspartate (NMDA) toxicity in tissue cultures. It has been suggested that the pathological disturbances in polyamine metabolism observed following cerebral ischemia, particularly the post-ischemic increase in putrescine, may contribute to the ischemic injury that is most evident in the CA1 subfield of the hippocampus. In this study, effects of DFMO in cerebral ischemia and reperfusion were examined. The results showed that inhibition of the polyamine system by DFMO decreased ischemic injury volume and brain tissue water content in a dose-dependent manner, without change in vital signs, including systemic arterial blood pressure, arterial partial oxygen pressure, regional cerebral blood flow and body temperature.

Surgical management of middle cerebral artery aneurysms: Surgical anatomy, approaches, and pitfalls

Aneurysms of the middle cerebral artery pose a significant challenge to neurosurgeons. The authors describe surgical techniques, clinical features, and different approaches to treat these aneurysms in light of surgical anatomy, lessons learned from complications, and personal experience.

Complications of surgical treatment of arteriovenous malformations

Abstract The management of cerebral arteriovenous malformations (AVMs) is one of the most important challenges for neurosurgeons. In this article, the authors discuss the preoperative issues that may lead to complications and intraoperative and postoperative complications of AVM surgery, as well as how to avoid them.