Atilla Akbay

Trabecular Architecture of Lumbar Vertebral Pedicle

Study Design. Investigation on architecture of lumbar pedicle. Objective. To determine morphological properties of pedicular cancellous bone. Summary of Background Data. Many researchers have been stimulated to study trabecular architecture by improvements in stereological technology. Although the structure of vertebral cancellous bone has been well studied in the literature, no information is available about the architecture of pedicular cancellous bone. Methods. Eight cadaveric L3 lumbar vertebrae were harvested. After colleting the bone mineral density (BMD) data on the vertebrae, pedicle isthmuses were removed from the vertebral bodies using a reciprocal hand saw. The BMD measurements were done on the dissected pedicle isthmus specimens. All the specimens were then analyzed using a micro-computed tomography unit. Morphologic parameters of trabecular bone were calculated. Results. Bone volume was found as 0.209 ± 0.046, whereas Tb.Th, Tb.Sp, and Tb.N were found to be 0.201 ± 0.035 mm, 0.930 ± 0.123 mm, and 1.098 ± 0.136 mm−1, respectively. Connectivity density and structure model index were observed to be 3.135 ± 0.918 mm−3, 0.37, whereas degree of anisotropy value was 1.241 ± 0.093. Vertebral BMD could explain 63% of variance in bone density of a pedicle isthmus. Conclusions. The structure of the pedicular cancellous bone is somewhat different from that of vertebral body. The trabecular architecture within the pedicle isthmus is isotropic and plate-like. The thickness and number of the trabeculae were greater than those of vertebral trabeculae. Decrease in the bone volume with age is mainly by thinning of the trabeculae and increasing in trabecular spacing, but not by loss of mass.

Ossified adamantinous type craniopharyngiomas. A series of 13 patients.

SummaryThirteen patients admitted to hospital mainly with visual disturbances (100%), retarded growth (39%) and diabetes insipidus (23%) were all diagnosed as ossified adamantinous craniopharyngioma. Tumour size was found to be large in all patients. Localization displayed a heterogenous dissemination; 8% intra-suprasellar, 69% suprasellar-extraventricular, 15% extra-intraventricular, and 8% in the suprasellar region extending bilaterally to the frontal and temporal lobes.During the early postoperative period, four patients died with hypothalamic deterioration. Three patients underwent a second operation in view of recurrence, and one died from an infection. Thus, the postoperative survival rate was 62%. All the patients who survived continued to have visual disturbances, but only one deteriorated. Five patients exhibited diabetes insipidus during the post-operative period, among them 4 after surgical intervention and 5 patients displayed panhypothyroidism, three of them after surgery.Consequently, it is confirmed by the present review that craniopharyngiomas still offer a potential dilemma in their management. Difficulties caused by adhesion or invasion of ossified craniopharyngiomas and thus the increase in morbidity and mortality during surgical intervention and in the postoperative period are discussed.

Reverse seeding of recurrent intraspinal malignant meningioma.

Meningiomas are common intracranial and intraspinal tumors and constitute 15–20% of all primary brain tumors. Ten to 15% of all meningiomas are considered malignant. The main treatment of meningiomas is surgical resection. Meningioma recurrence following surgery is frequent. However, it is not clear whether recurrent meningiomas, close or distant to the primary resection site, arise from incomplete resection, dissemination of tumor fragments or from independent tumor growth. We herein describe a 40-year-old woman with intraspinal malignant meningioma recurring each time upwards, i.e. apparently by reverse way of seeding, via cerebrospinal fluid.

Stress relaxation at the bone-pedicle screw interface in human bone

Study Design. A biomechanical study using human lumbar vertebra. Objectives. To assess the effects of stress relaxation on the pullout behavior of the pedicle screw in human bone. Summary of Background Data. The standard pullout test is widely used to assess screw-holding power; however, the effects of incremental deformation on the pullout behavior of pedicle screws are not known in human bone. A recent study in bovine bone suggests that stress relaxation during incremental pullout significantly reduces failure loads seen in pullout testing. Methods. Fourteen human lumbar vertebrae were instrumented with pedicle screws and tested with one of two pullout protocols: standard pullout model, a continuous withdrawal, and stress relaxation pullout model, an incremental withdrawal allowing stress relaxation. Peak loads and stiffness were calculated and relaxation data were assessed using the stretched exponential function. Results. Pullout strength and stiffness were significantly lower in the stress relaxation model group (P < 0.05). The characteristic relaxation time decreased and relaxation ratio increased with the increasing deformation level. The pullout and stress relaxation parameters were found to correlate with the bone quality. Conclusions. The stress relaxation process significantly affects the mechanical and viscoelastic properties of the bone–screw interface in human cadaveric bone. Stress relaxation pullout model might be a better representative of in vivo conditions by introducing the time and incremental deformation into the in vitro biomechanical testing.

Isolated paralysis of glossopharyngeal and vagus nerve associated with type II occipital condyle fracture: case report

IntroductionOccipital condyle fractures (OCFs) can occasionally be complicated with lower cranial nerve palsies.DiscussionIsolated 9th and 10th cranial nerve palsies following OCF are very rare. To our knowledge, we report the first case of an early onset of 9th and 10th cranial nerve palsies with an early full recovery in short period of time and discuss the probable mechanism of isolated nerve palsy in the light of the relevant literature.

Aneurysm Clip Compression Technique in the Surgery of Aneurysms with Hard/Calcified Neck

OBJECTIVE One of the most important technical problems in surgery to repair aneurysms is the presence of a hard/calcified neck. In this situation, various techniques can be used for proper clipping. In addition to well-known techniques, we have used a different technique for more than 10 years. This technique probably also has been used by other neurosurgeons, but we could not find any publications about it in the English literature. Therefore, we would like to report the details of this technique and our own experience. METHODS More than 600 anterior circulation aneurysms were clipped between January 2003 and December 2014. It was necessary to apply this technique in 25 aneurysms because of a hard/calcified neck. This series was reviewed retrospectively. If the hard-calcified plaque at the neck does not allow for full closure of the clip and the known techniques are not sufficient for clipping, we carefully and slowly compress the aneurysm clip itself at the neck with a hemostatic clamp. The hard plaque usually is crushed with this technique, and full closure of the clip is immediately obtained. RESULTS Complete occlusion of the neck was achieved in 16 aneurysms (64%) with this technique. Technique-related complication developed as intraoperative rupture of the aneurysm in two patients (8%). However, this complication was managed with other techniques in both cases. No distal thromboembolism developed in any patient. CONCLUSIONS Our aneurysm clip compression technique may be a viable option in surgery of aneurysms with hard-calcified neck.

Occipitocervical fixation using occipital bone hooks and cervical lateral mass screws: analysis of 16 cases.

AIM We present a series of 16 patients who underwent occipitocervical fixation with occipital bone hooks used as a substitute for occipital screws for the treatment of occipitocervical instability. MATERIAL AND METHODS In this technique; instrumentation was started following the decompression with insertion of screws into lateral masses. At the occipital level, two symmetrical burr holes were drilled and two occipital bone hooks were inserted into each burr hole with an inverted position with respect to each other. Afterwards, rod-plates were placed and locked on the hooks and screw heads. Bone grafting was also performed to achieve a solid fusion. RESULTS There were no neurological or vascular complications associated with this technique. No infection-related complications or hematomas were observed. Cerebro-spinal fluid leaks (CSF) occurred when the burr holes were drilled in 4 patients; however, these ceased when the occipital bone hooks were inserted. There were no cases of postoperative CSF fistula or pseudo-meningocele formation. No instrumentation problem was noted in any of the cases during the follow-up period. CONCLUSION Relatively long term (average 30.44 months) evaluation of the technique in terms of stability is satisfactory with no neurological, vascular or other major complications. However, further biomechanical studies are needed.

Hypothalamic hamartoma with bilateral anophthalmia.

IntroductionHypothalamic hamartomas are congenital malformations. Clinically, they can be asymptomatic, but they cause seizures, mental retardation and precocious puberty in many cases.Case reportA 20-day-old boy with hypothalamic hamartoma and bilateral anophthalmia was presented. Except those, no other congenital anomaly was detected.ConclusionThis is a rare case of hypothalamic hamartoma with bilateral anophthalmia. The mutations at SOX2 has an important role in the developing brain and eyes.

Cauda-filar paraganglioma with ‘silk cocoon’ appearance on spinal angiography

Summary.‘Silk cocoon’ appearance on spinal angiography is pathognomonic to differentiate paragangliomas from several vascular tumors and malformations of cauda-filar region.