Endoscopic anatomy of sphenoid sinus for pituitary surgery.

Endoscopic endonasal transsphenoidal approach to the sellar region yields an alternative to classical microsurgical approaches. Endoscopes provide images that differ from microscopic view. This study aimed to highlight surgical landmarks and their anatomical relationships for pituitary surgery through endoscopic perspective. Ten sides of five adult cadaveric heads with red-colored latex injected arteries were evaluated. Endoscopic dissections were performed and measurements were done in the sphenoid sinuses before and after the removal of bony structures in all the aspects. Endoscopic vision of the sellar region enabled a wide panoramic perspective and detailed inspection. The measurements, in general, indicated the variations in the bony structures and soft tissues. The width of the pituitary, which is the distance between the medial margins of the carotid prominences, was measured as 21 +/- 2.5 mm and the distance between the medial margin of the carotid prominences at the lower margin of the pituitary was 18 +/- 3.1 mm. After the bony structures were removed, further measurements were done. The width of the pituitary, which is the distance between the medial margins of the anterior curvature of the ICA, was measured as 23.2 +/- 3 mm, while the distance between the posterior curvature of the ICA was 19.7 +/- 4.9 mm. Endoscopic view provided superior detailed visualization of the close relationships between pituitary gland, internal carotid arteries, and optic nerves. This facilitated exact evaluation for variations, which could result in more effective and safe surgery. However, these variations again emphasize the necessity of preoperative radiological evaluation in each case.

Callosal branches of the anterior cerebral artery: an anatomical report.

Although the morphology of the corpus callosum is well defined, the arterial supply of this structure has not been comprehensively studied. To elucidate this further, 40 cerebral hemispheres from 30 adult cadaveric brains were obtained. The anterior cerebral arteries were cannulated and injected with red latex. The following were observed and documented: (1) the number, diameter, and course of the arteries supplying the corpus callosum; (2) the territories vascularized by these arteries; (3) any variations of the callosal arteries. Short callosal arteries were present in 58 hemispheres (96.6%) and supplied the superficial surface of the corpus callosum along its midline and were a primary arterial source to this structure. Long callosal arteries were found in 28 hemispheres (46.6%) and contributed to the pial plexus. The cingulocallosal arteries were present in all hemispheres and supplied the corpus callosum, cingulate gyrus, and also contributed to the pericallosal pial plexus. The recurrent cingulocallosal arteries were present in 17 hemispheres (28.3%) and also contributed to the pericallosal pial plexus. The median callosal artery, an anatomical variation, was present in 10 brains (33.3%). This vessel supplied the corpus callosum and the cingulate gyrus. The aim of the present study was to provide a detailed description of the arteries supplying the corpus callosum for those who encounter these vessels radiologically or surgically.

Keyhole approach for posterior cervical discectomy: experience on 84 patients.

Anterior cervical discectomy with or without fusion has been commonly used for cervical disc disease since the description by Smith and Robinson in 1958. In this report, surgical technique, advantages, and disadvantages of the posterior approach, known as the posterior keyhole laminotomy-foraminotomy, are reviewed and motion versus fusion surgery discussed. Between 1996 and 2004, the keyhole laminotomy-foraminotomy was performed on 84 patients suffering from lateral cervical soft disc herniation or osteophytes. All the procedures were performed under the surgical microscope. A high-speed drill was used for drilling the bone. In 49 patients (58%), soft disc herniation was removed, while in 35 patients (42%) there were osteophytes. Successful relief of radiculopathy symptoms was achieved in 80 patients (96%). In 4 patients the symptoms recurred. One patient (1.2%) developed kyphosis. The only complication observed intraoperatively was a partial root injury in one patient (1.2%). Mean hospitalization time was 48 hours. The posterior approach is particularly appropriate in patients whose root compression is located posterolaterally. Advantages of this surgery are minimal lamina resection, good visualization of the nerve root, postoperative early mobilization and minimal hospitalization. Microsurgery enables us to both preserve the motion of operated segment and avoid cervical instability.

The neurotoxic effects of intrathecal midazolam and neostigmine in rabbits.

In parallel with improvements in understanding pain neurophysiology, many chemicals have recently been investigated for spinal anaesthesia and analgesia. However, studies discussing the effects of these drugs on neural tissue indicate that knowledge about some aspects of neurotoxicity is limited. Forty-nine New Zealand albino rabbits, weighing 2.2 +/- 0.2 kg, were randomly assigned to seven groups of seven animals each. Single dose groups received intrathecally through the atlantooccipital membrane 0.9% saline 1.5 ml; midazolam 100 microg/kg (low dose midazolam group) or 500 microg/kg (high dose midazolam group); neostigmine 10 microg/kg (low dose neostigmine group) or 50 microg/kg (high dose neostigmine group). Two groups had seven days of repeated dosing with either midazolam 100 microg/kg/day (repeat midazolam group) or 10 microg/kg/day neostigmine (repeat neostigmine group). The animals were sacrificed on day 8, and two spinal cord sections from the fourth cervical level and fourth lumbar level were removed and prepared for histopathological study. Transmission electron microscopic evaluations were performed on transverse spinal cord sections by a neuropathologist blinded to the group allocation. Twenty myelinated axons and neurones in the cervical and lumbar sections were investigated for the histopathological study. This study indicates that midazolam and neostigmine have different neurotoxic effects that depend on the dose and the repetition of dosing when these drugs are administered intrathecally.

Infratemporal and intraorbital metastasis of the glioblastoma multiforme. A case report.

Primary brain tumors rarely metastasize outside of the central nervous system. A case of 37-year-old woman with a temporal lobe glial tumor which shows infratemporal and orbital invasion is presented. She had undergone a cranial operation because of temporal lobe epilepsy 8 years ago. Defects on the dura and bone flap were thought to be the mechanisms of the infratemporal fossa invasion. The case illustrates extra-axial metastasis of glioblastoma multiforme, an exceptional finding.

Fossa navicularis: anatomic variation at the skull base.

The fossa navicularis is a relatively rare anatomic variation of the skull base. Awareness of its existence will avoid misinterpretations of radiological images and unnecessary investigations. This study describes the appearance of the fossa navicularis, and investigates its incidence and whether it is related to pathology at the basiocciput. We studied 492 dry human skulls and 525 computer tomography (CT) images of patients. Dry skulls showing a fossa navicularis were investigated by CT scan, whereas patients identified as having a fossa navicularis were further examined with magnetic resonance imaging (MRI). To document the position of the fossa more precisely, measurements were made between the fossa navicularis and certain anatomic landmarks such as the foramen ovale, the pharyngeal tubercle, the posterior border of the vomer, the foramen lacerum, the carotid canal, and the occipital condyle. Upon examination, 26 of 492 skulls (5.3%) were found to have a fossa navicularis. Twelve were <2 mm in depth and the other 14 had a depth of >/=2 mm. Of the 525 patients, 16 (3.0%) were identified as having a fossa navicularis in CT images. Evaluation of MRIs showed no soft tissue lesions in any of these patients. Comprehensive anatomic details of the fossa navicularis have not been reported in the literature. The results of this study may be useful to radiologists, anatomists, and surgeons interested in the skull base.

Infection-related atlantoaxial subluxation in two adults: Grisel syndrome or not?

Grisel's syndrome involves the subluxation of the atlanto-axial joint from inflammatory ligamantous laxity following an infectious process in the head or neck. It is a rare disease usually affecting children, but infrequent adult cases do occur. Today, due to the widened use of antibiotics and availability of MR imaging, some cases presenting with neck pain, resulting from the infectious inflammation of C1 and C2 but without pronounced subluxation, can be a challenging problem for most neurosurgeons. Several theories have been proposed to explain the pathogenesis of inflammatory subluxation. The primary treatment of Grisel's syndrome is medical. The underlying infectious organism must be isolated and appropriate antibiotics must be prescribed. The subluxation is reduced in holter or skeletal traction. This paper reports two cases of infection-related atlanto-axial subluxation in two adults. The literature on this subject is briefly reviewed.

The effect of changing pressures on dural puncture and leak with various spinal needles on an in vitro model.

Postdural puncture headache is one of the most serious complications of spinal anesthesia. In this study, spinal needles of various types and shapes were used to investigate the amount of fluid leakage in dural puncture under various levels of pressures. Dura samples received from 10 cadavers were fixed in an in vitro model. The dural punctures were inflicted with 22 G, 25 G, and 27 G Quincke; 25 G Withacre; 25 G, 27 G Pencan, and 26 G Atraucan spinal needles. The fluid, which leaked during the process, was collected under the pressures of 0, 25, 50, 100, and 150 cm H(2)O in one-hour period for each level. The holes in the dura were studied under light microscope. While 22 G and 25 G Quincke needles were used, the fluid leakage directly correlated the amount of liquid, the diameter of the needle, and the pressure used. The puncture of 25 G Withacre and 25 G Pencan presented a leakage which did not significantly vary with the liquid pressure and was of lesser amount. In 26 G Atraucan, 27 G Pencan, and 27 G Quincke inflicted punctures, little liquid was collected and it did not vary with differing pressures. Thus, no significant correlation was established between the needle diameter and the puncture. It was concluded that the sharp-ended needles could not endure changes in the pressure. However, those needles with a very thin diameter and a pencil tip were considered as safe tools for anesthetical practices.

Is the asterion a reliable landmark for the lateral approach to posterior fossa?

An anatomical study was conducted to gain orientation regarding the posterolateral approaches. The asterion is defined as the junction of the lambdoid, parietomastoid, and occipitomastoid sutures. This anatomical point has been widely used as a landmark in lateral approaches to posterior fossa. Although there are many common practices in posterolateral approaches, studies providing accurate anatomical knowledge as to what is the correct point to start a craniotomy are limited in number. Therefore, this study was conducted in an attempt to determine the reliability of the asterion for the posterolateral approaches as surgical landmark.

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.

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.

Lumbar pedicle: surgical anatomic evaluation and relationships.

Although several clinical applications of transpedicular screw fixation in the lumbar spine have been documented for many years, few anatomic studies concerning the lumbar pedicle and adjacent neural structures have been published. The lumbar pedicle and its relationships to adjacent neural structures were investigated through an anatomic study. Our objective is to highlight important considerations in performing transpedicular screw fixation in the lumbar spine. Twenty cadavers were used for observation of the lumbar pedicle and its relations. After removal of whole posterior bony elements including spinous processes, laminae, lateral masses, and inferior and superior facets, the isthmus of the pedicle was exposed. Pedicle width and height (PW and PH), interpedicular distance (IPD), pedicle-inferior nerve root distance (PIRD), pedicle-superior nerve root distance (PSRD), pedicle-dural sac distance (PDSD), root exit angle (REA), and nerve root diameter (NRD) were measured. The results indicated that the average distance from the lumbar pedicle to the adjacent nerve roots superiorly, inferiorly and to the dural sac medially at all levels ranged from 2.9 to 6.2 mm, 0.8 to 2.8 mm, and 0.9 to 2.1 mm, respectively. The mean PH and PW at L1-L5 ranged from 10.4 to 18.2 mm and 5.9 to 23.8 mm, respectively. The IPD gradually increased from L1 to L5. The mean REA increased consistently from 35 degrees to 39 degrees. The NRD was between 3.3 and 3.9 mm. Levels of significance were shown for the P < 0.05 and P < 0.01 levels. On the basis of this study, we can say that improper placement of the pedicle screw medially and inferiorly should be avoided.

Chondroblastoma of the thoracic vertebra.

A 48-year-old patient with interscapular pain was admitted to our clinic. MRI revealed a mass infiltrating the second thoracic vertebra and adjacent structures. No other clinical manifestations were observed in general examination. The patient underwent surgery and subtotal removal was achieved while anterior and posterior stabilisations were performed. Diagnosis was pathologically confirmed. As thoracic chondroblastoma cases are not frequent, we decided to present this case.

Anteromedial approach to the orbit.

This study evaluated the surgical results of the anteromedial approach for treatment of orbital lesions in 16 patients. Pre- and postoperatively, all patients underwent a complete physical examination focusing on the head and neck area including a thorough ophthalmologic evaluation, computerized tomography, and magnetic resonance imaging. The surgical approach was limited to a medial orbitotomy in five patients; the remaining 11 patients underwent a medial orbitotomy combined with an external sphenoethmoidectomy. The tumor was removed completely without damaging the intraorbital neurovascular structures in all but one patient whose recurrent clival chordoma extended beyond the limits of an extracranial approach. Fibro-osseous lesions, cavernous hemangiomas, and dermoid cysts were the most common pathologies. The follow-up ranged from 18 to 48 months, and no patient has shown evidence of a recurrence. One patient with a clival chordoma received radiation therapy. The lateral nasal skin incision healed with acceptable cosmetic results. The anteromedial approach to the orbit provides a wider working space and direct exposure while protecting neurovascular structures.

Zygomatic anterior subtemporal approach for lesions in the interpeduncular cistern.

The interpeduncular cistern is a difficult region to approach through conventional methods due to its deep location and important adjacent neurovascular structures. Therefore, it is usually difficult to expose the region sufficiently. Technical problems associated with various surgical approaches have led to emergence of combined approaches and their modifications (i.e., the removal of the zygomatic arch). In addition, a frontotemporal craniotomy is reported to provide a wide exposure of the anterior temporal base, thus allowing oblique access to the interpeduncular cistern with minimal brain retraction. This study describes clinicians' experience and the surgical results of 24 patients who underwent a zygomatic anterior subtemporal approach.

Effects of iloprost on vasospasm after experimental spinal cord injury: an electron and light microscopic study.

It has been increasingly reported that traumatic and ischemic insults to the spinal cord may produce tissue damage through both direct and indirect mechanisms. In spite of many theories about post-traumatic spinal cord injury, there is still no satisfactory account of the exact mechanism. Vasospasm may be related to the trauma and release of vasoconstrictor or vasoactive amines. This study aims at studying the possible protective mechanisms of iloprost, a stable analogue of prostacyclin, after spinal cord injury on the rabbit. Forty-two adult male rabbits (New Zealand albino) were inflicted injuries by epidural application of an aneurysm clip to the spinal cord. Twenty-one rabbits received an i.v. infusion of 25 microg kg(-1) x h(-1) iloprost. The remaining twenty-one rabbits received an i.v. infusion of saline as the control group. Intravenous treatment started immediately after the infliction of the spinal cord injury and lasted for 1 h. Iloprost treatment had no side effects on the general physiological parameters in the rabbits. Control and iloprost treatment groups were divided into three sub-groups. The first group of animals was deeply anesthetized and spinal cords were removed 15 min after treatment. Second and third group animals were sacrificed in the 3rd and 24th hours respectively. All spinal cords were removed for light and electron microscopic examination. The width of anteriolar smooth muscle cells and the ultrastructural analysis of sulcal arterioles and venules in the ventral median fissure of spinal cords treated by iloprost revealed less thickening in all groups especially on the 24th hour group (p < 0.01), but less thickening was observed on the 3rd hour group. Iloprost-treated groups had limited edema and moderate protection of myelin and axons. These results suggest that iloprost treatment after spinal cord injury has a highly protective effect, and the possible protective effect of iloprost is resolution of vasospasm due to spinal cord injury.

The neurosurgical management of prolactinomas.

BACKGROUND: The objective was to discuss the neurosurgical management of the prolactinomas. METHODS: Five-hundred-fifty patients suffering from prolactinoma were treated with trans-sphenoidal and transcranial approach. The diagnosis of prolactinoma was based on various degree of high level prolactinemia, galactorrhea, gonodal disturbance, neurological examination and radiological findings. In all cases the adenoma was histologically verified. The patients were investigated according to the anatomo-radiological classification of Hardy and Vesina, and the range of preoperative PRL basal levels. RESULTS: Follow-up was ascertained in 81% of patients who were followed for a mean of 7.2 year (1-10 year). While the total removal percentage was 98% in the group with microprolactinoma, this ratio dropped to 63.9% for macroadenomas and 23.5% for giant adenomas. Early improvement of prolactin level ratio was 81.6% in microprolactinomas, 28.3 in macroadenomas and 11.7% in giant adenomas. Hormonal cure was 64.3% in microadenomas, 6.7% in macroadenomas and 0% in giant adenomas. The ratio of hormonal cure was decreasing in patients with high prolactin levels. In the follow-up recurrence of prolactinomas occurred in 39% of the patients. CONCLUSIONS: Medical treatment is the first step in prolactin secreting adenomas. Trans-sphenoidal microsurgery became popular in treatment of prolactinomas because of low operative morbidity and mortality. Patients with recurrence should be evaluated for second step treatment (surgery, bromocriptine, or radiotherapy).

Surgical anatomic evaluation of the cervical pedicle and adjacent neural structures.

OBJECTIVE: Although 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. METHODS: Twenty 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. RESULTS: The 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. CONCLUSION: This 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.

Anatomical projection of the cervical uncinate process in ventral, ventrolateral, and posterior decompressive surgery.

OBJECT: The cervical uncinate processes (UPs), their variations, and the relationships between the neurovascular structures and surrounding bone were investigated in this anatomical study. The object of this study was to highlight the important surgery-related considerations associated with ventral, ventrolateral, and posterior decompressive surgery. METHODS: Forty-nine adult C3-7 dry bone samples were used, and 10 measurements were obtained for each vertebra. The anterior measurements involved the cervical uncinate process (UP): height, width, length, distance between its tip and vertebral foramina, interuncinate process distance, sagittal angle with the superior margin of the vertebral body (VB), VB anteroposterior diameter, and VB width. Posterior measurements involved the vertical distance between the superior border of the lamina at the lamina-facet joint and the tip of the UP, as well as the horizontal distance between the medial-most border of the superior facet and the tip of the UP. All symmetrical structures were measured bilaterally. There were no statistically significant differences between right- and left-sided measurements in this series. The height of the UP increased gradually at each segmental level between C-3 and C-7. The width of the UP did not change with segmental level (5.0 mm at C-3 compared with 5.3 mm at C-7). On average, the length of the UP was relatively constant. The distance from the tip of the UP to vertebral foramina averaged 1 mm at the C2-3 level and 1.5 mm at the C5-6 level. Interuncinate distance and VB width gradually increased and were highly variable, which appeared to be related with osteophyte formation. There was a slight gradual increase from C-3 to lower segments, and it paralleled with the midline anteroposterior diameter of the same VB. The angle between the UP and the superior margin of the VB exhibited great variety. The posterior measurements decreased gradually from C-3 to C-7. CONCLUSIONS: Based on the data obtained in this study, a surgeon is provided with a three-dimensional orientation as well as anatomical knowledge. This knowledge also allows for a more effective neurovascular decompression by minimizing the surgery-related complications.

Patients with urinary incontinence often benefit from surgical detethering of tight filum terminale.

We retrospectively reviewed 77 patients with a tethered spinal cord syndrome to evaluate the results of neurosurgical treatment. The patients were divided into two groups: in group 1 there were 17 patients with primary tethered cord who had normal level conus medullaris (NLCM) and normal thickness filum terminale (NTFT) with urinary incontinence, and group 2 was made up of 60 patients with secondary spinal cord tethering after a previous closure of a midline fusion defect who had a low-lying conus medullaris. Neurological examination, radiography, urodynamic tests and electrophysiological findings confirmed the diagnosis. Conventionally, tethered cord syndrome has been defined as a state in which the conus medullaris is located below the L1-2 disc space. However, in a patient with urinary incontinence and a hyperreflexive type of neurogenic bladder, in whom the conus medullaris is found to be at the normal level, there may still be cord tethering that is causing the incontinence. In this study the comparison was based on evaluation of the response to treatment and general characteristics of the syndrome in both groups of patients to draw attention to the general approach to this incapacitating mal-development.