Nihat Egemen

Thoracic pedicle: surgical anatomic evaluation and relations.

This anatomic study investigated the thoracic pedicle and its relations. The objective was to emphasize the importance of the thoracic pedicle for transpedicular screw fixation to avoid complications during surgery. Twenty cadavers were used to observe the cervical pedicle and its relations. The isthmus of the pedicle was exposed after removal of whole-posterior bony elements, including spinous processes, laminas, lateral masses, and the inferior and superior facets. The pedicle width and height, interpedicular distance, pedicle-inferior nerve root distance, pedicle-superior nerve root distance, pedicle-dural sac distance, root exit angle, and nerve root diameter were measured. There was no distance between the pedicle and dural sac in eight specimens. There was, however, a short distance in 12 remaining specimens in the upper and lower thoracic regions. The distances between the thoracic pedicle and the adjacent nerve roots ranged from 1.5 to 6.7 mm and 0.8 to 6.0 mm superiorly and inferiorly at all levels. The mean pedicle height and width at T1-T12 ranged from 2.9 to 11.4 mm and 6.2 to 21.3 mm, respectively. The interpedicular distance decreased gradually from T1 to T5 and then increased gradually to T12. The mean root exit angle decreased consistently from 104 degrees to 60 degrees. The nerve root diameter was between 2.3 and 2.5 mm at the T1-T5 level and then increased consistently from 2.5 to 3.7 mm. All significant differences were noted at p < 0.05 and p < 0.01. The following suggestions are made based on these results. 1) More care should be taken when a transpedicular screw is placed in the horizontal plane. 2) Improper medial placement of the pedicle screw, especially in the middle thoracic spine, should be avoided, and the anatomic variations between individuals should be considered. 3) Because of substantial variations in the size of thoracic pedicles, utmost attention should be given to the findings of a computed tomographic evaluation before thoracic transpedicular fixation is begun.

Surgical Anatomic Evaluation of the Cervical Pedicle and Adjacent Neural Structures

OBJECTIVEAlthough several clinical applications of transpedicular screw fixation in the cervical spine have been documented recently, few anatomic studies concerning the cervical pedicle are available. This study was designed to evaluate the anatomy and adjacent neural relationships of the middle and lower cervical pedicle (C3–C7). The main objective is to provide accurate information for transpedicular screw fixation in the cervical region and to minimize complications by providing a three-dimensional orientation. METHODSTwenty cadavers were used to observe the cervical pedicle and its relationships. After removal of the posterior bony elements, including spinous processes, laminae, lateral masses, and inferior and superior facets, the isthmus of the pedicle was exposed. Pedicle width, pedicle height, interpedicular distance, pedicle-inferior nerve root distance, pedicle-superior nerve root distance, pedicle-dural sac distance, medial pedicle-dural sac distance, mean angle of the pedicle, root exit angle, and nerve root diameter were measured. RESULTSThe results indicate that there was no distance between the pedicle and the superior nerve root and between the pedicle and the dural sac in 16 specimens, whereas there was a slight distance in the lower cervical region in the 4 other specimens. The mean distance between the pedicle and the inferior nerve root for all specimens ranged from 1.0 to 2.5 mm. The mean distance between the medial pedicle and the dural sac increased consistently from 2.4 to 3.1 mm. At C3–C7, the mean pedicle height ranged from 5.2 to 8.5 mm, and the mean pedicle width ranged from 3.7 to 6.5 mm. Interpedicular distance ranged from 21.2 to 23.2 mm. The mean root exit angle ranged from 69 to 104 degrees, with the largest angle at C3 and the smallest at C6. The mean angle of the pedicle ranged from 38 to 48 degrees. The nerve root diameter increased consistently from 2.7 mm at C3 to 3.8 mm at C6 and then decreased to 3.7 mm at the C7 level. Differences in measurements were considered statistically significant at levels ranging from P < 0.05 to P < 0.01. CONCLUSIONThis study indicates that improper placement of the pedicle screw medially and superiorly in the middle and lower cervical spine should be avoided and that the anatomic variations between individuals should be established by measurement.

The effect of intrathecal sodium nitroprusside on severe chronic vasospasm

The efficacy of sodium nitroprusside in resolving cerebral vasospasm was evaluated with multicisternal injections. Twelve animals received fresh, unheparinized arterial blood via three injections (15 ml total) into the cisterna magna. Selective vertebral arteriography was performed on Day 0, and blood injections were performed on the second and third days after the first injection. On the seventh day selective arteriography was performed to evaluate the diameter of the basilar artery. In the sodium nitroprusside group, intrathecal injections of the drug were started on Day 4 and continued for two days (25 micrograms/kg/day). The diameter of the basilar artery was reduced 72.98 +/- 11.07% in control experiments. For the animals treated with intrathecal sodium nitroprusside, the mean diameter of the basilar artery was reduced 29.25 +/- 4.54%. The effect of intrathecal sodium nitroprusside on intracranial pressure (ICP), blood pressure (BP) and electrocardiogram (ECG) was also evaluated in 14 animals. There were no prominent changes in ICP, BP, or ECG when sodium nitroprusside was given intrathecally, but BP decreased and ICP and heart rate increased with intravenous doses of sodium nitroprusside. These results support the hypothesis that sodium nitroprusside administered intrathecally is an effective treatment for cerebral vasospasm.

Primary Intradural Extramedullary Hydatid Cyst

Spinal hydatid cysts account for 1% of all cases of hydatid disease; primary intradural hydatid cysts are uncommon. We present a case of pathologically confirmed intradural spinal cyst hydatid in an otherwise healthy patient who showed no other evidence of systemic hydatid cyst disease. The patient presented with back pain, paraparesis, and weakness. An intradural extramedullary cystic lesion was identified with magnetic resonance imaging and was shown to be a hydatid cyst by histopathologic examination after surgical removal. To our knowledge, this is the 25th case of hydatid cyst at an intradural extramedullary location reported in the literature.

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.

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

Evaluation of cerebral vasospasm in patients with subarachnoid hemorrhage using single photon emission computed tomography.

Cerebral vasospasm (CVS) occurs as a result of the breakdown in cerebral autoregulation mechanisms. Because cerebral vasospasm can occur after subrachnoid hemorrhage (SAH), it is important to evaluate borderline perfusion. Evaluation of borderline vascular insufficiency is important to reduce ischemic complications. In this study 25 patients with SAH were investigated by somatosensory evoked potentials (SEP), computed tomography (CT), digital subtraction angiography (DSA) and single photon emission computed tomography (SPECT) in order to predict borderline ischemic areas. Clinical grades were also correlated with these investigations. Thirteen patients had symptomatic vasospasm and 15 patients had angiographic vasospasm. SPECT showed hypoperfusion in 22 out of 25 patients. CT predicted CVS in 8 of these 22 patients. Our study shows that brain perfusion SPECT is a non-traumatic, non-invasive, non-allergic, inexpensive method for the prediction of cerebral vasospasm. We conclude that brain SPECT with Tc-99m HM-PAO is an accessible technique that can demonstrate varying degrees of regional tissue hypoperfusion in patients with delayed ischemic deficits due to CVS following SAH.

Craniopharyngioma of the Posterior Fossa

A case of craniopharyngioma originating in the very unusual location of the posterior fossa is presented. The patient, a 23-year-old man, was operated on at another hospital when he was 3 years old for craniopharyngioma in the suprasellar area. There was no complaint for several years after this initial operation. Three months before he was admitted to our hospital, he had complaints of headache, vomiting, nausea, and ataxia. A computed tomographic scan revealed a mass with a cyst and calcifications in the posterior fossa. The tumor was removed totally.

Surgical treatment of intracranial cavernous angiomas

We present a surgical series of 35 patients (25 males and 10 females) with histopathologically verified intracranial cavernous angiomas. The 35 malformations were located as follows: 21 were in the cerebral hemispheres; 4 in the lateral ventricles, 4 in the brain stem; and 6 in the cerebellum. Seizures and focal neurological deficits were the main clinical features observed in patients with intracranial cavernous angiomas. A number of these vascular malformations were misdiagnosed by computerized tomography. In the last 10 years, magnetic resonance imaging has been the most sensitive method for detecting these lesions. Thirty-five cavernous angiomas were treated surgically; in 33 patients a complete excision, and in 2 patients subtotal excision were obtained. One of the patients died one year after the operation. The overall outcome was good in all of the 34 remaining patients, resulting in improved seizure control or neurological deficit. The rationale for neurologic differential diagnosis and surgical treatment and follow up results are discussed.

The vasorelaxant effect of dipyrone on an experimental cerebral vasospasm model in rabbits.

Abstract Cerebral vasospasm is an important clinical phenomenon associated with a high mortality rate and therefore any promising findings in the laboratory deserve assessment in clinical practice. Dipyrone (Metamizol) has been in clinical use for its non-narcotic analgesic effect since 1922. In addition to its analgesic effect, dipyrone has been shown to possess spasmolitic activity in various smooth muscle organs. In our recent study, it was shown that dipyrone also has a relaxing effect in vascular smooth muscle preparations and that the smooth muscle relaxing effect on the rabbit thoracic aorta was produced by one of dipyrone’s spontaneous degradation products. The present study was designed to examine the possible effects of dipyrone on the rabbit basilar artery in a model of cerebral vasospasm. Dipyrone was shown to have a clear spasmolitic effect in the rabbit basilar artery vasospasm produced by an intracisternal injection of autologous blood. This effect was apparent with either local or intravenous administration of dipyrone. These data suggest that dipyrone is potentially useful in the treatment of patients suffering from cerebral vasospasm in combination with other agents or alone. [Neurol Res 2000; 22: 815-818]