Haluk Deda

Duplication of the abducens nerve at the petroclival region. An anatomic study

OBJECTIVEDuring its course between the brainstem and the lateral rectus muscle, the abducens nerve usually travels forward as a single trunk, but it is not uncommon for the nerve to split into two branches. The objective of this study was to establish the incidence and the clinical importance of the duplication of the nerve. METHODSThe study was performed on 100 sides of 50 autopsy materials. In 10 of 11 cases of duplicated abducens nerve, colored latex was injected into the common carotid arteries and the internal jugular veins. The remaining case was used for histological examination. RESULTSFour of 50 cases had duplicated abducens nerve bilaterally. In seven cases, the duplicated abducens nerve was unilateral. In 9 of these 15 specimens, the abducens nerve emerged from the brainstem as a single trunk, entered the subarachnoid space, split into two branches, merged again in the cavernous sinus, and innervated the lateral rectus muscle as a single trunk. In six specimens, conversely, the abducens nerve exited the pontomedullary sulcus as two separate radices but joined in the cavernous sinus to innervate the lateral rectus muscle. In 13 specimens, both branches of the nerve passed beneath the petrosphenoidal ligament. In two specimens, one of the branches passed under the ligament and the other passed over it. In one of these last two specimens, one branch passed over the petrosphenoidal ligament and the other through a bony canal formed by the petrous apex and the superolateral border of the clivus. In all of the specimens, both branches were wrapped by two layers: an inner layer made up of the arachnoid membrane and an outer layer composed of the dura during its course between their dural openings and the lateral wall of the cavernous segment of the internal carotid artery. This finding was also confirmed by histological examination in one specimen. CONCLUSIONDouble abducens nerve is not a rare variation. Keeping such variations in mind could spare us from injuring the VIth cranial nerve during cranial base operations and transvenous endovascular interventions.

Tumours of the lateral ventricle. A retrospective review of 112 cases operated upon 1970–1997

Between the years 1970 and 1997, 112 patients with tumors of the lateral ventricle were operated on at the University of Ankara, School of Medicine, Department of Neurosurgery. Seventy-one patients (63.4 %) were male and 41 patients (36.6 %) female. Headache (35.7 %), nausea and vomiting (22.3 %) were the most common presenting complaints. Papilloedema (42.9 %), motor and sensory loss (25 %) were the most common findings at neurological examination. Complete tumor removal was accomplished in 38.4 % of the patients. Histopathologically, the most commonly seen types of the tumor were ependymoma (25 %) and astrocytoma (21.4 %). Among the various approach, the anterior transcortical (53.6 %) and the posterior transcortical (16 %) were the most commonly used. Eleven patients were reoperated for tumor recurrence. After surgery, radiation therapy was also performed on fourty-two patients. The morbidity and mortality rates were considerably higher before 1976 when the use of microneurosurgical techniques was introduced. After this, our morbidity and mortality rates decreased dramatically. The overall surgical mortality rate was 7.1 % before 1976; during the last 10 years (n:46), it was 6.5 %. In this report, our choice of operative approaches and the results will be discussed.

The jugular foramen: A comparative radioanatomic study

BACKGROUND Advances in microsurgical techniques made possible the removal of advanced jugular foramen (JF) lesions, which once had been accepted as unoperable. However, successful surgery requires detailed knowledge of the JF anatomy. METHODS Sixteen jugular foramina in eight formalin-preserved adult cadavers were scanned with axial and coronal high resolution computed tomography (HRCT) prior to dissection. After craniectomy and removal of brain tissue, the relationships of the neurovascular structures in the JF were determined by drilling the temporal bones from superior to inferior on planes parallel to the skull base. RESULTS No bony partition of the JF was observed. A dural band consistently divided the JF into two parts. Anterior to it was the glossopharyngeal nerve (IX) while the vagus (X) and accessory (XI) nerves were located posteriorly. There was a notch in which the IX nerve entered the JF. It was also identified on the CT scans and defined as the glossopharyngeal recess. The IX nerve made a genu within the JF in all specimens. Then, it ran inferiorly through a bony canal in three specimens (18.75%), and through an incomplete bony canal in two (12.5%), which were also defined on the CT images. The inferior petrosal sinus ran through a sulcus anteromedial to the glossopharyngeal recess. The posterior meningeal artery was found to be located between the X and XI nerves within the JF. CONCLUSIONS This study revealed a complex and highly variable pattern of the relationships of the neurovascular structures in the JF, and their HRCT images correlated well with the anatomic microdissections.

Tentorial meningiomas. Commentaries

We report our experience with and long-term results of 37 patients with tentorial meningiomas who underwent surgery between 1972 and 1993. The average age was 43 years, and the mean duration of symptoms was 36 months. Headache (83.8%) and extremity or gait ataxia (35.1%) were the most common complaints. On neurological examination, signs of elevated intracranial pressure and cerebellar deficits (51.4%) were the most common findings, followed by third nerve involvement (35.1%). Computed tomography, angiography, and, in recent years, magnetic resonance imaging were used as diagnostic tools and for planning the surgical procedure. According to the primary site of attachment, the tentorial meningiomas were divided into three subgroups: medial, lateral, and falcotentorial

Olfactory groove meningiomas.

Meningiomas originating from the olfactory groove account for approximately 10% of all intracranial meningiomas. They represent only 2% of all intracranial tumors. We present the diagnostic, clinical and pathological features of olfactory groove meningiomas and describe our surgical results and complications in a series of 25 patients. In 19 patients, surgery was via a bifrontal approach, and in the remaining six a pterional approach was used.

Comprehensive microsurgical anatomy of the jugular foramen and review of terminology

The microsurgical anatomy of the jugular foramen was studied in 12 formalin preserved cadavers (24 foramina) and 40 dry-skulls (80 foramina). The jugular foramen was exposed by microsurgical dissection with drilling from a superior to inferior direction. Observations regarding dural architecture of the jugular foramen and relationships between neurovascular structures passing through the foramen were noted in cadavers. Normal bony construction of the foramen and its variational anatomy were examined in dry-skull specimens. Using photographs and drawings, the anatomy of the jugular foramen is presented and related terminology is discussed in the light of a literature review.

Pituitary abscesses. Report of three cases

Three cases of pituitary abscess are presented. In spite of improvements in radiological evaluation, preoperative diagnosis of pituitary abscess is quite difficult and definite preoperative diagnosis is rare in the literature. In our three cases, diagnosis was made postoperatively. Pituitary abscesses are associated with high mortality and morbidity. When first suspected, prompt antibiotic therapy should be considered. Early operative drainage seems to be an important factor in decreasing this high mottality and morbidity.

Differential diagnosis of idiopathic inflammatory trigeminal sensory neuropathy from neuroma with a biopsy: case report.

OBJECTIVE AND IMPORTANCE Idiopathic inflammatory trigeminal sensory neuropathy (IITSN) is a disorder with the dominant clinical features of trigeminal sensory disturbance; this idiopathic condition follows a benign course in most cases. Recent reports have shown that transient abnormalities, which may mimic those of trigeminal neuromas, can be observed in magnetic resonance imaging scans. Presented here is a case of IITSN that was diagnosed, with cytological and histopathological verification, during the active inflammatory phase of the disease (the first such attempt, to our knowledge). CLINICAL PRESENTATION A 20-year-old female patient was referred to our hospital with a 2-month history of numbness of the left side of her face, headache, and hemifacial pain attacks. Cranial magnetic resonance imaging scans revealed a mass above and below the foramen ovale, extending into the cavernous sinus. INTERVENTION A percutaneous biopsy procedure through the foramen ovale was performed; the pathological examination revealed lymphocytes, macrophages, and endothelial cells but no evidence of neoplastic cells. A few days later, the patient was surgically treated using a cranial base approach, the gasserian ganglion was exposed, and the lesion was removed. Pathological examination of the specimens revealed inflammatory changes and fibrosis of the nerve fibers and ganglion cells. Disruption of the myelin around the nerve bundles was detected. Therefore, IITSN was pathologically confirmed during the early stage of the disease. During 3 months of follow-up monitoring, the patient experienced no serious clinical problems. CONCLUSION IITSN should be suspected in cases of tumors involving the cavernous sinus, and a percutaneous biopsy through the foramen ovale should be performed as part of the differential diagnosis in such cases. This procedure might obviate unnecessary aggressive surgery. In the current case, no neoplastic cells were observed during the examination; only lymphocytes, macrophages, and endothelial cells were observed, on a background of erythrocytes. Lymphocyte-dominant inflammatory infiltration, fibrotic changes, and demyelinization are cardinal histopathological findings observed during the active phase of IITSN.

Radiological anatomy of the intratemporal course of facial nerve.

Preoperative evaluation of the facial nerve (FN) anatomy within the temporal bone by high‐resolution computed tomography (HRCT) helps in minimizing surgical trauma to the nerve. In order to demonstrate the radiological correlation of the intratemporal FN, eight adult, formalin‐preserved cadavers were studied by comparing the transaxial and coronal sections of HRCT with anatomic microdissection findings. It was possible to visualize all segments of the FN canal in its intratemporal course. The most difficult part of the FN to demonstrate was the pyramidal section. Anatomic microdissection findings were consistent with the HRCT images. It was concluded that adequate information on the FN anatomy could be obtained from standard HRCT scans. Clin. Anat. 13:83–87, 2000.

AN ANATOMICAL STUDY OF THE TYMPANIC BRANCH OF THE GLOSSOPHARYNGEAL NERVE (NERVE OF JACOBSON)

Our study was aimed to examine the anatomic relationships of the tympanic branch of the glossopharyngeal nerve (GPN), namely the Jacobsons nerve (JN). The JN is the first branch of the GPN after having passed the jugular foramen. It contributes to the tympanic plexus on the promontory. It transmits secretory innervation to the parotid gland. Its possible role in the regulation of the middle ear pressure has also been hypothesized in terms of animal studies. Using microdissection techniques and high-resolution computed tomography (HRCT) scanning, the anatomic relationships and course of the JN were examined in eight formalin-preserved cadavers (16 sides). A morphometric analysis related to the JN was also performed both in the 16 cadavers and 40 dry-skull specimens. The JN emerged from the inferior ganglion of the GPN in all specimens. The mean distance between the ganglion and the genu of the GPN was 11.3 mm. The inferior 2/3 of the tympanic canal (TC) followed a vertical course, and then it ran anteromedially with an angle of 160 degrees to 170 degrees. The mean length of the TC was 9.5 mm. The TC was well-defined in all axial HRCT scans. In 2 cases the JN was entirely encased in a bony canal in the middle ear. A double JN was observed in one case. This study gives an additional information regarding the anatomy of the JN.