Peripapillary retina nerve fiber layer thickness and macular ganglion cell layer thickness in patients with obstructive sleep apnea syndrome.

PurposeTo investigate the association of the severity of obstructive sleep apnea syndrome (OSAS) with peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell-inner plexiform layer (GC-IPL).Materials and methodsIn this cross-sectional study, 145 patients with OSAS and 40 healthy subjects were enrolled. OSAS patients were further divided into mild (n=50), moderate (n=36), and severe (n=59) OSAS groups according to their apnea-hypopnea index (AHI) values. Spectral-domain optical coherence tomography was used to measure the peripapillary RNFL and GC-IPL thicknesses.ResultsThere was no statistical difference between the RNFL thickness in OSAS and control groups (P>0.05). Both average GC-IPL and minimum GC-IPL thicknesses were significantly lower in severe OSAS group than in healthy controls (P<0.05 for both). There was a significant negative correlation between AHI and both average GC-IPL (r=-0.232, P=0.005) and minimum GC-IPL (r=-0.233, P=0.005) thicknesses.ConclusionsOur study results suggest that although RNFL thickness did not differ significantly between OSAS and control groups, ganglion cell layer thickness in OSAS patients is much lower than in healthy population. Ganglion cell thickness showed a significant correlation with the severity of OSAS.

Case report: subarachnoid anesthesia for kyphoplasty: is anesthesia adequate?

We performed a prospective pilot study of subarachnoid anesthesia for kyphoplasty in 11 nonrandomized patients. Subarachnoid anesthesia was administered at the level of the best palpable intervertebral space below L3. Patients received intrathecally either hyperbaric or plain bupivacaine with or without fentanyl. Five patients experienced pain during the surgical procedure and received supplemental IV analgesia. One patient felt pain from the pressure on the ribs while in the prone position. The remaining patients were comfortable. In no patient was respiratory compromise or deep sedation observed. We conclude that subarachnoid anesthesia may be an adequate technique for kyphoplasty.

Microsurgical anatomy of the dorsal cervical rootlets and dorsal root entry zones.

BACKGROUND: Detailed anatomical knowledge of the dorsal cervical rootlets and dorsal root entry zones (DREZ) is important for the diagnosis and treatment of cervical myeloradiculopathy and surgical management of pain. There are far fewer micro-anatomical studies of this area than gross anatomical studies. This study presents several anatomical points regarding the dorsal cervical rootlets and dorsal root entry zones. METHOD: Fifteen adult formalin-fixed cadaveric spines from C1 to T1 were used to observe the posterior structures. They were studied under the surgical microscope following en bloc laminectomy and foraminotomy. The morphological features of the dorsal root entry zones and dorsal rootlets were determined. The distance from the midline to the DREZ, the longitudinal length of the DREZ in the spinal canal, the length of the dorsal rootlets, the number of dorsal rootlets and the intersegmental anastomoses between the dorsal rootlets were measured. FINDINGS: The distance from the midline to the DREZ ranged from 1.1 to 4.7 mm. Longitudinal length of the dorsal rootlets ranged 4.3-17.7 mm. The shortest length of the dorsal rootlets ranged between 5-28 mm, and longest lengths of the dorsal rootlets ranged 6.8-30.3 mm. The number of dorsal rootlets ranged from 2-13. Between the C2-T1 dorsal rootlets, 142 connections out of 30 intersegments were noted. CONCLUSIONS: The distance from the midline to the DREZ decreased in the lower cervical spine. The longest longitudinal length of the DREZ was at the C5 level. The length of the dorsal rootlets was increased in the lower cervical spine. The average number of dorsal rootlets tended to increase in the lower cervical spine. Anastomoses were most often found between C6-7 and C5-6 dorsal rootlets. Knowledge of the anatomical features of dorsal cervical rootlets and dorsal root entry zones is essential for a surgeon to avoid injuring the neural structures. This knowledge is a must not only to avoid complications but also for the success, safety and effectiveness of microsurgical operations of the pathological conditions like posterior myeloradiculopathy and pain treatment such as DREZ operations.

Stereotactically-guided fourth ventriculo-peritoneal shunting for the isolated fourth ventricle.

The isolated fourth ventricle (IFV) develops in which obstruction to the out flow of cerebrospinal fluid from the choroid plexus of the fourth ventricle occurs rostrally and caudally. IFV has been a rare occurrence and is difficult to treat. We had an occasion to admit a 28-year-old female to our hospital due to hydrocephalus: she also had a history of meningitis a year ago. The patient was initially managed by a lateral ventriculo-peritoneal shunting procedure. Six months after the procedure the patient began to suffer from vomiting, nausea, and diplopia. CT and MRI scans demonstrated an isolated fourth ventricle enlargement; and thus, a fourth ventriculo-peritoneal shunting procedure was performed under stereotactic conditions. The authors present a case of an isolated fourth ventricle after lateral ventriculo-peritoneal shunting for hydrocephalus, which was treated with a stereotactically guided fourth ventriculo-peritoneal shunting procedure. The technique of this procedure is described below.

Neurological function-based research.

Function of the nervous system has been the main domain of interest of an elite group of philosophers, scientists and physicians. This topic may only be understood within a historical perspective, since the progression of knowledge of the function of the nervous system has always paralleled the expansion of our understanding of the outer world and of biological organisms observed. However, data gained from functional experimental and clinical researches in neurosurgery, neurology and neuroscience constitute not only a traditional and historical accumulation of this knowledge but also serve as one of the most important aspects of experimental and clinical neuroscience in the future. This article summarizes the basic principles and methods used in neurological function-based research. In order to elucidate the topic, the text was practically divided into three main sections: (1) historical perspective regarding functional research models in clinical and experimental neuroscience; (2) neurological function-based clinical studies in humans; and (3) experimental research models on animals.

CT-guided percutaneous selective cordotomy for treatment of intractable pain in patients with malignant pleural mesothelioma.

Malignant mesotheliomas are neoplasms that arise from mesothelial cells and cause intractable pain in the chest wall, usually located unilaterally. This local pain can be well controlled by computerized tomography (CT)-guided percutaneous cordotomy (PC). One hundred and fifty-three patients suffering from intractable pain due to malignancy were treated with CT-guided cordotomy between 1988 and 2001. Seventy of the 153 patients had pulmonary malignancy. Among these, 40 had bronchogenic carcinoma, 11 had Pancoast tumors and the remaining 19 had mesothelioma. The latter 19 cases with malignant mesothelioma suffering from unilateral pain were treated with CT-guided PC. In 18 cases, pain was controlled totally and, in one, partial pain control was obtained. Selective pain control was obtained in 15 cases, in whom narcotic drugs were discontinued postoperatively. Post-cordotomy dysesthesia was noted in only one case, and no complication or mortality was observed. In the treatment of intractable pain, CT-guided cordotomy is a perfect method in selected cases with malignancy. This is the most effective and suitable treatment modality for local pain due to malignant mesothelioma.

The effects of continuous and single-dose radiation on choline uptake in organotypic tissue slice cultures of rabbit hippocampus.

The objective of the present study was to determine the time-dependent course of choline uptake in mature organotypic slice cultures of rabbit hippocampal formation and to assess the effects of continuous and single high-dose irradiation on choline uptake in cultivated slices in vitro. Transverse slices of hippocampus were dynamically incubated in a cerebrospinal fluid-like culture medium for 72 h. To study the changes in choline uptake longitudinally, the slice cultures were processed with 0.1 microM [3H]-choline, and tritium accumulation was counted. Two different gamma irradiation sources (125I seeds and a clinical 60Co source) were used as representative models of interstitial radiosurgery and other radiosurgical techniques. A total dose of approximately 6000 cGy was delivered to the brain slices in one session or in a continuous, relatively low-dose rate fashion, and their effects on high-affinity choline uptake were examined. In another set of experiments with 125I, 5 microM hemicholinium-3 was used in choline uptake procedures as a competitive high-affinity choline uptake inhibitor. The results can be summarized as follows: (1) in the control group of the hippocampal tissue culture, there was a significant increase in tritium accumulation values from 0 to 48 h and a decrease thereafter; (2) continuous 125I irradiation caused a highly significant depression of the accumulation of tritium compared to that observed in the control group throughout its application for 72 h; (3) there was no significant change in the accumulation of tritium in the slices after single high-dose rate irradiation with a 60Co source; and (4) 5 microM hemicholinium significantly depressed the accumulation of tritium in both the control and the 125I-irradiated groups, and there was no longer a difference between 125I-irradiated and control groups when both groups were treated with hemicholinium. These results demonstrate that the delivery of continuous but relatively low-dose rate gamma irradiation is more efficacious than single high-dose external irradiation on high-affinity choline uptake in hippocampal nervous tissue. The results also indicate that continuous irradiation specifically affected the high-affinity energy-dependent choline uptake mechanism, whereas nonspecific choline uptake did not seem to be disturbed.

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.

Percutaneous controlled radiofrequency trigeminal rhizotomy for the treatment of idiopathic trigeminal neuralgia: 25-year experience with 1,600 patients.

OBJECTIVE: The objective of this study was to evaluate the effectiveness of percutaneous, controlled radiofrequency trigeminal rhizotomy (RF-TR). The outcome of 1,600 patients with idiopathic trigeminal neuralgia after RF-TR was analyzed after a follow-up period of 1 to 25 years. METHODS: A total of 1,600 patients with idiopathic trigeminal neuralgia underwent 2,138 percutaneous radiofrequency rhizotomy procedures between 1974 and 1999. Sixty-seven patients had bilateral idiopathic trigeminal neuralgia, and 36 of them were treated with bilateral RF-TR; 1,216 patients (76%) were successfully managed with a single procedure, and the remainder were treated with multiple procedures. Benzodiazepines and narcotic analgesics were used for anesthesia because patient cooperation during the procedures was essential so that the physician could create selective, controlled lesions. RESULTS: The average follow-up time was 68.1 +/- 66.4 months (range, 12-300 mo). Acute pain relief was accomplished in 97.6% of patients. Complete pain relief was achieved at 5 years in 57.7% of the patients who underwent a single procedure. Pain relief was reported in 92% of patients with a single procedure or with multiple procedures 5 years after the first rhizotomy was performed. At 10-year follow-up, 52.3% of the patients who underwent a single procedure and 94.2% of the patients who underwent multiple procedures had experienced pain relief; at 20-year follow-up, 41 and 100% of these patients, respectively, had experienced pain relief. No mortalities occurred. After the first procedure was performed, early pain recurrence (<6 mo) was observed in 123 patients (7.7%) and late pain recurrence was observed in 278 patients (17.4%). Complications included diminished corneal reflex in 91 patients (5.7%), masseter weakness and paralysis in 66 (4.1%), dysesthesia in 16 (1 %), anesthesia dolorosa in 12 (0.8%), keratitis in 10 (0.6%), and transient paralysis of Cranial Nerves III and VI in 12 (0.8%). Permanent Cranial Nerve VI palsy was observed in two patients, cerebrospinal fluid leakage in two, carotid-cavernous fistula in one, and aseptic meningitis in one. CONCLUSION: Percutaneous, controlled RF-TR represents a minimally invasive, low-risk technique with a high rate of efficacy. The procedure may safely be repeated if pain recurs.

Chiari Type I malformation presenting as glossopharyngeal neuralgia: case report.

OBJECTIVE AND IMPORTANCE: Chiari Type I malformation is an important pathological state in which the brainstem is compressed by the cerebellar tonsil. We present a case of glossopharyngeal neuralgia caused by Chiari Type I malformation. CLINICAL PRESENTATION: A 50-year-old male patient was admitted with glossopharyngeal neuralgia. Magnetic resonance imaging studies revealed caudal displacement of the left cerebellar tonsil. INTERVENTION: Small occipital craniectomy and C1 laminectomy were performed. The left cerebellar tonsil was resected. CONCLUSION: This glossopharyngeal neuralgia was caused by compression of the lower cranial nerves and brainstem by the displaced left cerebellar tonsil. Decompression and pain relief were obtained with resection of the cerebellar tonsil. The patient was pain-free 30 weeks after the operation.

Evidence that the rat osteopetrotic mutation toothless (tl) is not in the TNFSF11 (TRANCE, RANKL, ODF, OPGL) gene.

The toothless (tl) osteopetrotic mutation in the rat affects an osteoblast-derived factor that is required for normal osteoclast differentiation. Although the genetic locus remains unknown, the phenotypic impact of the tl mutation on multiple systems has been well characterized. Some of its actions are similar to tumornecrosis factor superfamily member 11(TNFSF11; also called TRANCE, RANKL, ODF and OPGL) null mice. TNFSF11 is a recently described member of the tumor necrosis factor superfamily which, when expressed by activated T cells, enhances the survival of antigen-presenting dendritic cells, and when expressed by osteoblasts, promotes the differentiation and activation of osteoclasts. The skeletal similarities between tl rats and TNFSF11(-/-) mice include 1) profound osteoclastopenia (TNFSF11-null mice, 0% and tl rats 0-1% of normal); 2) persistent, non-resolving osteopetrosis that results from 3) a defect not in the osteoclast lineage itself, but in an osteoblast-derived, osteoclastogenic signal; and 4) a severe chondrodysplasia of the growth plates of long bones not seen in other osteopetrotic mutations. The latter includes thickening of the growth plate with age, disorganization of chondrocyte columns, and disturbances of chondrocyte maturation. These striking similarities prompted us to undertake studies to rule in or out a TNFSF11 mutation in the tl rat. We looked for expression of TNFSF11 mRNA in tl long bones and found it to be over-expressed and of the correct size. We also tested TNFSF11 protein function in the tl rat. This was shown to be normal by flow cytometry experiments in which activated, spleen-derived T-cells from tl rats exhibited normal receptor binding competence, as measured by a recombinant receptor assay. We also found that tl rats develop histologically normal mesenteric and peripheral lymph nodes, which are absent from TNFSF11-null mice. Next, we found that injections of recombinant TNFSF11, which restores bone resorption in null mice, had no therapeutic effect in tl rats. Finally, gene mapping studies using co-segregation of polymorphic markers excluded the chromosomal region containing the TNFSF11 gene as harboring the mutation responsible for the tl phenotype. We conclude that, despite substantial phenotypic similarities to TNFSF11(-/-) mice, the tl rat mutation is not in the TNFSF11 locus, and that its identification must await the results of further studies.

Percutaneous controlled radiofrequency rhizotomy in the management of patients with trigeminal neuralgia due to multiple sclerosis.

Between the years 1974 and 1999, 1,672 patients with medically intractable trigeminal neuralgia (TN) were treated by percutaneous controlled radiofrequency (RF) rhizotomy by the senior author and co-workers at the Department of Neurosurgery, Ankara University School of Medicine. Sixteen hundred cases (95.7%) were found to have idiopathic TN, while 72 cases (4.3%) were classified as symptomatic. In the latter group, TN was found to be caused by multiple sclerosis (MS) in 17 cases (23.6%), one of whom had bilateral TN. All patients having TN with MS (17 cases) underwent percutaneous controlled radiofrequency rhizotomy (25 procedures) as the procedure of choice. The MS patients were followed for an average of 60 months (range: 6-141 months). Complete pain relief was achieved with a single procedure in 12 of the 17 MS cases (70.6%). Early (less than 2 weeks) pain recurrence was seen in two patients (11.8%), while the overall recurrence rate was 29.4%. A second procedure was required to control TN in three cases (17.6%), a third in one (5.9%), and twice for each side for the case with bilateral TN (5.9%). Pain was completely relieved in 14 cases (82.4%) with single or multiple RF rhizotomies. In three cases (17.6%), partial pain control was achieved with RF rhizotomy, and the patients continued to receive adjunctive medical therapy. No complications were observed. All 17 patients (100%) were classified to have done well with RF rhizotomy. Satisfactory results and good long-term pain control were obtained in patients having TN due to MS with percutaneous controlled RF rhizotomy. The authors propose that RF rhizotomy may be a safe and effective procedure in the neurosurgical armamentarium for the treatment of patients having TN due to MS.

Endochondral bone formation in toothless (osteopetrotic) rats: failures of chondrocyte patterning and type X collagen expression.

The pacemaker of endochondral bone growth is cell division and hypertrophy of chondrocytes. The developmental stages of chondrocytes, characterized by the expression of collagen types II and X, are arranged in arrays across the growth zone. Mutations in collagen II and X genes as well as the absence of their gene products lead to different, altered patterns of chondrocyte stages which remain aligned across the growth plate (GP). Here we analyze GP of rats bearing the mutation toothless (tl) which, apart from bone defects, develop a progressive, severe chondrodystrophy during postnatal weeks 3 to 6. Mutant GP exhibited disorganized, non-aligned chondrocytes and mineralized metaphyseal bone but without cartilage mineralization or cartilaginous extensions into the metaphysis. Expression of mRNA coding for collagen types II (Col II) and X (Col X) was examined in the tibial GP by in situ hybridization. Mutant rats at 2 weeks exhibited Col II RNA expression and some hypertrophied chondrocytes (HC) but no Col X RNA was detected. By 3rd week, HC had largely disappeared from the central part of the mutant GP and Col II RNA expression was present but weak and in 2 separate bands. Peripherally the GP contained HC but without Col X RNA expression. This abnormal pattern was exacerbated by the fourth week. Bone mineralized but cartilage in the GP did not. These data suggest that the tl mutation involves a regulatory function for chondrocyte maturation, including Col X RNA synthesis and mineralization, and that the GP abnormalities are related to the Col X deficiency. The differences in patterning in the tl rat GP compared to direct Col X mutations may be explained by compensatory effects.