The morphometric and cephalometric study of anterior cranial landmarks for surgery.

OBJECTIVE: The aim of this work was to determine reliable bony landmarks for the anterior skull base and to standardize some specific dimensions among the frontal sinus and neighboring structures for safe anterior cranial surgery. METHODS: The study consisted of a topographical anatomic examination and cephalometric analysis of the skull. Thirty adult skulls (60 sides) were studied regarding the localization and dimensions of the supraorbital foramen (SOF), frontal sinus (FS), frontozygomatic fissure, infraorbital foramen, anterior nasal spine, and nasion. Differences between the measurement of skulls and cephalograms were analyzed by Student's t test. The Pearson correlation test was used for statistical analysis of the cephalogram. RESULTS: Examination of the 60 sides of the bony heads revealed that the shape of the SOF was a foramen in 25 sides (41%), a notch in 29 sides (49%), and a groove in 6 sides (10%). A total of 20 (33%) SOFs were inside the FS and the mean distance was 6.3+1.34 mm from the lateral border of the sinus, 27 (45%) of SOFs were outside of the FS and the mean distance was 8.8+2.01 mm, and 13 (22%) of SOFs were at the border of the FS. According to our measurements the medial border of the craniotomy should be placed approximately 43 mm lateral to the nasion to avoid entering into the frontal sinus. CONCLUSION: To plan and to decide the convenient and safe anterior midline skull base approach and to avoid postoperative complications, bony landmarks and anatomic measurements around the SOF and FS will be helpful for the surgeon to constitute a simplification of topographic anatomy.

Critically located cavernous malformations.

INTRODUCTION: The aim of this study was to evaluate the clinical results of patients who underwent resection with the aid of microsurgical techniques and stereotactic and image-guided surgery for critically located cavernous malformations which still represent a considerable surgical challenge due to the close proximity of vital and eloquent structures. METHODS: Between 1997 and 2003, 12 patients with critically located cavernous malformations (CMs) underwent surgical resections at Ankara University Hospital. CMs of the pons (n=3), medulla oblongata (n=1), cavernous sinus (n=3), motor cortex (n=4) and the newly defined superior cerebellar peduncle (n=1) were treated using image-guidance and advanced microsurgical principles. Preoperative assessment was done with CT, MRI and angiography. Lesion locations, clinical presentations and outcome were analyzed. The surgical approach was chosen as lateral suboccipital (n=4), parietal (n=4), cranio-orbitozygomatic (n=3) and retrosigmoid (n=1). RESULTS: All CMs were readily identified and completely removed with no permanent morbidity and mortality. The immediate outcome after surgery was improved for 8 patients (66.6%). Long-term outcome was unchanged for one patient and a proved good surgical outcome for three patients, during the mean follow-up period. DISCUSSION: Stereotactic methods together with image-guidance and microsurgical techniques allow the creation of most effective and safe corridors to access the CMs in eloquent regions with a minimization of tissue manipulation and low risk of permanent neurological deficit.

"Triple cross" of the hypoglossal nerve and its microsurgical impact to entrapment disorders.

OBJECTIVE: Cadaveric dissections were performed to review the intracranial and extracranial course of the hypoglossal nerve. The neurological significance of a newly defined "triple cross" of the hypoglossal nerve is discussed. MATERIALS AND METHODS: 10 cadaveric heads (left and right; 20 sides) were dissected using microsurgical techniques. RESULTS: In the cisternal segment of hypoglossal nerve, the diameter of the rostral trunk amounted to 155-680 microm (mean 435 microm), and the caudal trunk to 210-820 microm (mean 482 microm). The roots formed three trunks in 20% of the hypoglossal nerves and two trunks in the rest. As a first cross, the anterior medullary segment of the vertebral artery crossed the hypoglossal nerve roots in 14 of 20 sides (70%). As a rare variation, the vertebral artery extended medial to the nerve (25%) or between its roots (5%). The second cross was found between the descendens hypoglossus and the occipital artery (75%), sternocleidomastoid artery and vein complex (15%) and external carotid artery (10%). The third cross was shown in the submandibular triangle between the lingual hypoglossus and its drainage vein; vena committans nervus hypoglossus. CONCLUSION: Throughout its way, the hypoglossal nerve passes over vascular structures in three crossing points which may serve as a probable cause of hypoglossal nerve entrapment disorders.

Non-traumatic elevation techniques of the hypoglossal nerve during carotid endarterectomy: a cadaveric study.

OBJECTIVE: Ligation and dissection techniques of sternocleidomastoid artery, vein, ansa cervicalis and posterior belly of digastric muscle were developed in a cadaveric study for achieving minimally invasive elevation of the hypoglossal nerve during carotid endarterectomy and were subsequently used in patient treatment. METHODS: Carotid bifurcations, the extracranial part of the hypoglossal nerve, the sternocleidomastoid artery and vein and neighboring neurovascular structures were studied on 10 formalin-fixed adult cadaver heads (20 sides) under the surgical microscope. Landmarks and measurements for identification of the sternocleidomastoid artery and vein are described. RESULTS: The distance between the hypoglossal loop and the carotid bifurcation was measured as 14.5 - 25.2 mm (mean: 19.24 mm). 30 % of 20 sides were determined to have a Zone II-type carotid bifurcation. In 33 % of the Zone-II-type bifurcations, a low-lying hypoglossal loop was demonstrated. The sternocleidomastoid artery begins 2.2 - 3.5 mm (mean: 2.94 mm) supero-posterior from the occipital artery after the crossing point between the occipital artery and the hypoglossal nerve. The sternocleidomastoid artery and vein complex was 17.1 - 21.5 mm (mean 18.47 mm) away from the carotid bifurcation and forms a right angle with the descending hypoglossal nerve. The contribution of the sternocleidomastoid branch of the occipital artery always reaches the middle parts of the sternocleidomastoid muscle. CONCLUSION: Carotid endarterectomy through having knowledge of the normal and variable trajectories of the structures can almost always be accomplished as a safe procedure when appropriate maneuvers are applied. Dissection and ligation of the sternocleidomastoid artery, vein, ansa cervicalis and posterior belly of digastric muscle are very simple but effective techniques to obtain adequate exposure either for safe arterial reconstruction or to diminish the necessity for more complicated technical procedures.

Selective microsurgical vestibular neurectomy: an option in the treatment of intractable vertigo and related microsurgical landmarks.

Selective microsurgical vestibular neurectomy (SMVN) is an accepted and effective means of treating patients with intractable vertigo, a resistant component of Meniere's syndrome. Meniere's syndrome is a condition characterized by fluctuating hearing loss, tinnitus and serious vertigo attacks. Vertigo is the most disabling symptom of the disease. There may be permanent hearing loss in untreated cases and vertigo may continue after deafness. Selective microsurgical vestibular neurectomy is an elite surgical procedure providing exact relief from vertigo while protecting the preoperative hearing level. In this report, clinical results of nine patients with intractable vertigo operated in the University of Ankara Medical Faculty, Department of Neurosurgery between 1999 and 2001 are discussed. Accordingly, we aimed to represent the landmarks often required for microsurgical exposure. From this study we conclude that SMVN is an effective neurosurgical procedure for those patients who are resistant for medical treatment and require hearing preservation.

Growth dynamics of meningiomas in patients with multiple sclerosis treated with interferon: report of two cases.

BACKGROUND: Although multiple sclerosis (MS) is a common disease of the central nervous system, the association of intraparenchymal tumour has been rarely reported and the potential relationship between intracranial meningioma and MS has not been seriously analysed. This report addresses the association of multiple sclerosis and intracranial meningioma and discusses the effect of interferon treatment on tumour progression. CLINICAL PRESENTATION: We report two cases with multiple sclerosis, who developed meningioma four and twenty years after the diagnosis of MS was made. Neither patient had a history of meningioma initially and both were being treated interferon when the meningioma was progressed. FINDINGS: Histological examination of two cases revealed meningothelial meningioma. The first patient's KI67 level was 2.5% and was positive for the progesterone and estrogen receptor. Chromosomal analysis showed some abnormalities. In the second case, mild atypical change by presence of nuclear enlargement and rare mitotic figures were noted and PCNA, KI67 levels were less than 2%. CONCLUSIONS: We reported the association of multiple sclerosis and intracranial meningioma and observed the progression of the meningiomas during interferon treatment. Although, we cannot exclude the coincidence between the two diseases we discussed suspicious relationship between the interferon treatment and the tumour progression.

Glabellar frown lines as a reliable landmark for the supratrochlear artery.

OBJECTIVE: Preservation of the supratrochlear vascular pedicle (SVP) during use of the paramedian forehead flap can be accomplished by the aid of Doppler imaging; however, a reliable surface landmark may be invaluable in cases where Doppler examination fails. Our observations showed that the most prominent glabellar frown lines (GFLs) are very close to the SVP; however, the actual relationship of these structures remains unclear. STUDY DESIGN: The relationship between GFLs and the SVP was investigated in 19 volunteers by the aid of Doppler imaging and in 8 cadaver heads by dissection. The distance between the GFLs and the SVP was measured. SETTING: The study took place at an academic tertiary-care facility. RESULTS: The SVP was located just at the GFLs in almost 50% of the cases and an average of 3.2 mm lateral to GFLs in the remaining cases. CONCLUSION: GFLs may serve as reliable surface landmarks in the use of the paramedian forehead flap where Doppler imaging was not helpful.

Computed tomography-guided trigeminal tractotomy-nucleotomy in the management of vagoglossopharyngeal and geniculate neuralgias.

OBJECTIVE: Vagoglossopharyngeal and geniculate neuralgias are less frequently seen types of cranial neuralgias. Their causes and symptomatology are similar to those of trigeminal neuralgia; however, the complex anatomic relationship between the intermedius, vagal, and glossopharyngeal nerves leads to difficulties in the diagnosis and management of neuralgias originating from these cranial nerves. Numerous procedures have been used to treat intractable neuralgias of the VIIth, IXth, and Xth cranial nerves: 1) extracranial sectioning of the cranial nerves, 2) percutaneous thermal rhizotomy, 3) intracranial glossopharyngeal and vagal rhizotomies, 4) microvascular decompression, and 5) percutaneous trigeminal tractotomy-nucleotomy (TR-NC) or nucleus caudalis dorsal root entry zone operation. We propose that computer-guided TR-NC may be the first-choice operation for patients with glossopharyngeal, vagal, or geniculate neuralgia. PATIENTS AND METHODS: Nine patients suffering from idiopathic vagoglossopharyngeal neuralgia (six patients) and geniculate neuralgia (three patients) were managed at our clinic. Computed tomography-guided percutaneous trigeminal TR-NC was performed for these nine patients. RESULTS: Excellent (six patients) or good (three patients) pain control was obtained in each patient. Complications included temporary ataxia in two patients after TR-NC. CONCLUSION: The risk:benefit ratio should be evaluated individually to select the appropriate treatment procedure for patients with vagoglossopharyngeal and geniculate neuralgias. Computed tomography-guided percutaneous TR-NC is an effective and minimally invasive procedure for such patients.