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OBJECTIVE A recent comparative analysis between neurosurgical and endovascular treatments for craniocervical junction (CCJ) arteriovenous fistulas (AVFs) revealed better treatment outcomes in the neurosurgery group than in the endovascular group. This finding was attributed to the higher than expected rate of ischemic complications in the endovascular group than in the neurosurgery group (26% vs 7.7%, p = 0.037). The aim of the present study was to describe ischemic complications associated with treatments for CCJ AVFs. METHODS This descriptive study was authorized by the Neurospinal Society of Japan. Data from 97 consecutive patients with CCJ AVFs who underwent neurosurgical (n = 78) or endovascular (n = 19) treatment between 2009 and 2019 were collected from 29 centers. The primary endpoints were details on ischemic complications and their risk factors. Secondary endpoints were details on other complications. RESULTS Among all major complications, ischemic complications were the most common (11% of 97 patients), followed by hemorrhagic complications (7.2%), hydrocephalus (2.1%), and CSF leakage (2.1%). Ischemic complications included 8 spinal, 2 brainstem, and 1 cerebellar infarctions. Iatrogenic occlusion of the anterior or posterior spinal artery from the radiculomedullary or radiculopial arteries caused these complications. Ischemic complications resulted in neurological deficits, including motor paresis, sensory disturbances, and brainstem dysfunction. The modified Rankin Scale score was 3 or higher in 36% of patients with ischemic complications at the final follow-up of 23 months. Risk factors associated with ischemic complications were endovascular treatment (OR 4.3, 95% CI 1.1–16) and spinal feeding arteries (OR 3.8, 95% CI 1.03–14). Most of the other complications were addressed by additional treatment without permanent neurological deficits. CONCLUSIONS Among ischemic complications associated with treatments for CCJ AVFs, spinal infarctions were the most common and were mostly attributed to endovascular procedures for CCJ AVFs fed by spinal arteries. These results support the use of neurosurgery as the first-line treatment for CCJ AVFs.

OBJECTIVESpinal arteriovenous shunts are rare vascular lesions and are classified into 4 types (types I–IV). Due to rapid advances in neuroimaging, spinal epidural AVFs (edAVFs), which are similar to type I spinal dural AVFs (dAVFs), have recently been increasingly reported. These 2 entities have several important differences that influence the treatment strategy selected. The purposes of the present study were to compare angiographic and clinical differences between edAVFs and dAVFs and to provide treatment strategies for edAVFs based on a multicenter cohort.METHODSA total of 280 consecutive patients with thoracic and lumbosacral spinal dural arteriovenous fistulas (dAVFs) and edAVFs with intradural venous drainage were collected from 19 centers. After angiographic and clinical comparisons, the treatment failure rate by procedure, risk factors for treatment failure, and neurological outcomes were statistically analyzed in edAVF cases.RESULTSFinal diagnoses after an angiographic review included 199 dAVFs and 81 edAVFs. At individual centers, 29 patients (36%) with edAVFs were misdiagnosed with dAVFs. Spinal edAVFs were commonly fed by multiple feeding arteries (54%) shunted into a single or multiple intradural vein(s) (91% and 9%) through a dilated epidural venous plexus. Preoperative modified Rankin Scale (mRS) and Aminoff-Logue gait and micturition grades were worse in patients with edAVFs than in those with dAVFs. Among the microsurgical (n = 42), endovascular (n = 36), and combined (n = 3) treatment groups of edAVFs, the treatment failure rate was significantly higher in the index endovascular treatment group (7.5%, 31%, and 0%, respectively). Endovascular treatment was found to be associated with significantly higher odds of initial treatment failure (OR 5.72, 95% CI 1.45–22.6). In edAVFs, the independent risk factor for treatment failure after microsurgery was the number of intradural draining veins (OR 17.9, 95% CI 1.56–207), while that for treatment failure after the endovascular treatment was the number of feeders (OR 4.11, 95% CI 1.23–13.8). Postoperatively, mRS score and Aminoff-Logue gait and micturition grades significantly improved in edAVFs with a median follow-up of 31 months.CONCLUSIONSSpinal epidural AVFs with intradural venous drainage are a distinct entity and may be classified as type V spinal vascular malformations. Based on the largest multicenter cohort, this study showed that primary microsurgery was superior to endovascular treatment for initial treatment success in patients with spinal edAVFs.

Background: The redundant nerve root (RNR) syndrome is a pathological condition in which the cauda equina develops into a severely flexed/tortuous spiral mass above a level of severe lumbar stenosis. Case Description: A 70-year-old male presented with bilateral neurogenic claudication attributed to a MRI-documented intradural extramedullary lesion at the L1 level with severe adjacent level/inferior L2/3 stenosis. At surgery, intradural exploration at L1 revealed an edematous cauda equina consistent with the diagnosis of the RNR syndrome. Conclusion: The RNR syndrome should be included among the differential diagnostic considerations when non-enhancing lesions are encountered above levels of marked lumbar stenosis.

OBJECTIVE Craniocervical junction (CCJ) arteriovenous fistulas (AVFs) are treated using neurosurgical or endovascular options; however, there is still no consensus on the safest and most effective treatment. The present study compared the treatment results of neurosurgical and endovascular procedures for CCJ AVFs, specifically regarding retreatment, complications, and outcomes. METHODS This was a multicenter cohort study authorized by the Neurospinal Society of Japan. Data on consecutive patients with CCJ AVFs who underwent neurosurgical or endovascular treatment between 2009 and 2019 at 29 centers were analyzed. The primary endpoint was the retreatment rate by procedure. Secondary endpoints were the overall complication rate, the ischemic complication rate, the mortality rate, posttreatment changes in the neurological status, independent risk factors for retreatment, and poor outcomes. RESULTS Ninety-seven patients underwent neurosurgical (78 patients) or endovascular (19 patients) treatment. Retreatment rates were 2.6% (2/78 patients) in the neurosurgery group and 63% (12/19 patients) in the endovascular group (p < 0.001). Overall complication rates were 22% and 42% in the neurosurgery and endovascular groups, respectively (p = 0.084). Ischemic complication rates were 7.7% and 26% in the neurosurgery and endovascular groups, respectively (p = 0.037). Ischemic complications included 8 spinal infarctions, 2 brainstem infarctions, and 1 cerebellar infarction, which resulted in permanent neurological deficits. Mortality rates were 2.6% and 0% in the neurosurgery and endovascular groups, respectively (p > 0.99). Two patients died of systemic complications. The percentages of patients with improved modified Rankin Scale (mRS) scores were 60% and 37% in the neurosurgery and endovascular groups, respectively, with a median follow-up of 23 months (p = 0.043). Multivariate analysis identified endovascular treatment as an independent risk factor associated with retreatment (OR 54, 95% CI 9.9–300; p < 0.001). Independent risk factors associated with poor outcomes (a postoperative mRS score of 3 or greater) were a pretreatment mRS score of 3 or greater (OR 13, 95% CI 2.7–62; p = 0.001) and complications (OR 5.8; 95% CI 1.3–26; p = 0.020). CONCLUSIONS Neurosurgical treatment was more effective and safer than endovascular treatment for patients with CCJ AVFs because of lower retreatment and ischemic complication rates and better outcomes.

OBJECTIVE In cervical spondylotic myelopathy (CSM), compromise of blood flow to the compressed spinal cord has been postulated to contribute to the development of myelopathy. Although decompressive surgery has been considered to improve spinal cord blood flow, evidence to support this notion is scarce. To determine whether blood flow improves after decompressive surgery for CSM, regional blood flow was measured in a model of chronic cervical compression in rats by using a fluorescent microsphere technique. METHODS Thin polyurethane sheets, measuring precisely 3 × 5 × 0.7 mm, were implanted under the C5–6 laminae in 24 rats to induce continuous compression on the cervical spinal cord. These sheets expand gradually by absorbing tissue fluid. This animal model has been demonstrated to reproduce the clinical features and histological changes of CSM, including progressive motor weakness with delayed onset and insidious tissue damage prior to symptom onset. Twenty-four rats that underwent sham operation were allocated to a control group. To confirm the development of cervical myelopathy, motor functions were measured weekly over the study period. Nine weeks after implantation of the sublaminar expanding sheets, histological studies and C5–6 decompressive surgery were conducted. Regional blood flow in the brainstem and cervical spinal cord was measured sequentially until 120 minutes after decompression. RESULTS In the CSM group, bilateral forepaw grip strength deteriorated progressively from 5 weeks after implantation. In the compressed C5–6 segment of the spinal cord, significant flattening of the cord, a decreased number of motor neurons, and vacuolations of gray matter were demonstrated. In the control group, blood flow in the brainstem and cervical spinal cord was unchanged by the decompressive surgery. In the CSM group, however, diminished blood flow and continuous blood flow increments for 120 minutes after decompression were demonstrated in the compressed C5–6 spinal cord segment. CONCLUSIONS Chronic mechanical compression induced regional spinal cord blood flow insufficiency concomitant with progressive neuronal loss and motor dysfunction in a chronic compression model in rats. Decompressive surgery increased spinal cord blood flow. These findings suggest that blood flow recovery may contribute to postoperative neurological improvement.

OBJECTIVEThe purpose of the present study was to compare the treatment success rates of primary neurosurgical and endovascular treatments in patients with spinal dural arteriovenous fistulas (dAVFs).METHODSData from 199 consecutive patients with thoracic and lumbosacral spinal dAVFs were collected from 18 centers. Angiographic and clinical findings, the rate of initial treatment failure or recurrence by procedures, risk factors for treatment failure, complications, and neurological outcomes were statistically analyzed.RESULTSSpinal dAVFs were frequently detected in the thoracic region (81%), fed by a single feeder (86%), and shunted into an intradural vein via the dura mater. The fistulous connection between the feeder(s) and intradural vein was located at a single spinal level in 195 patients (98%) and at 2 independent levels in 4 patients (2%). Among the neurosurgical (n = 145), and endovascular (n = 50) treatment groups of single dAVFs (n = 195), the rate of initial treatment failure or recurrence was significantly higher in the index endovascular treatment group (0.68% and 36%). A multivariate analysis identified endovascular treatment as an independent risk factor with significantly higher odds of initial treatment failure or recurrence (OR 69; 95% CI 8.7–546). The rate of complications did not significantly differ between the two treatment groups (4.1% for neurosurgical vs 4.0% for endovascular treatment). With a median follow-up of 26 months, improvements of ≥ 1 point in the modified Rankin Scale (mRS) score and Aminoff-Logue gait and Aminoff-Logue micturition grades were observed in 111 (56%), 121 (61%), and 79 (40%) patients, respectively. Independent risk factors for lack of improvement in the Aminoff-Logue gait grades were multiple treatments due to initial treatment failure or recurrence (OR 3.1) and symptom duration (OR 1.02).CONCLUSIONSBased on data obtained from the largest and most recently assessed multicenter cohort, the present study shows that primary neurosurgery is superior to endovascular treatment for the complete obliteration of spinal dAVFs by a single procedure.

Study design Basic animal research. Objective The effects of granulocyte colony-stimulating factor (G-CSF) were assessed in a rat chronic spinal cord compression model to explore the potential of G-CSF as a pharmacological treatment for cervical spondylotic myelopathy. Summary of background data G-CSF is a hematopoietic cytokine used clinically to treat neutropenia. Recently, neuroprotective effects of G-CSF have been reported in spinal cord disorders. Methods To introduce the chronic cervical cord compression, thin polyurethane sheets were implanted under C5-C6 laminae of rats and gradually expanded by absorbing water. This model reproduces delayed compressive myelopathy of the cervical spine. In sham operations, the sheets were immediately removed. G-CSF (15 μg/kg) or normal saline (NS) was administered subcutaneously 5 days a week. Experimental groups were sham operation given NS; cord compression given NS; and cord compression given G-CSF. To assess motor functions, rotarod performance, and grip strength were measured. Twenty-six weeks after surgery, cervical spinal cords were examined histopathologically. In the prevention experiment, G-CSF or NS administration was started immediately after surgery. In the treatment experiment, their administration was started 8 weeks after surgery. In another experiment, in three groups in the prevention experiment, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling staining was performed to assess apoptotic cell death at 8 weeks after surgery. Results In the prevention experiment, administration of G-CSF preserved the motor functions and motor neurons throughout the 26 weeks, and significantly decreased the number of apoptotic cells at 8 weeks. In the treatment experiment, G-CSF administration from 8 weeks after surgery markedly restored the motor function temporarily to a level equal to the sham group. Conclusion G-CSF prevents the decline in motor functions and preserves motor neurons in the rat chronic cord compression model. G-CSF also improves motor function in the progressive phase of compression myelopathy. Level of evidence N/A.

Background Motor evoked potential (MEP) recording is used as a method to monitor integrity of the motor system during surgery for intramedullary tumors (IMTs). Reliable sensitivity of the monitoring in predicting functional deterioration has been reported. However, we observed false positives and false negatives in our experience of 250 surgeries of IMTs. Objective To delineate specificity and sensitivity of MEP monitoring and to elucidate its limitations and usefulness. Methods From 2008 to 2011, 58 patients underwent 62 surgeries for IMTs. MEP monitoring was performed in 59 operations using transcranial electrical stimulation. Correlation with changes in muscle strength and locomotion was analyzed. A group undergoing clipping for unruptured aneurysms was compared for elicitation of MEP. Results Of 212 muscles monitored in the 59 operations, MEP was recorded in 150 (71%). Positive MEP warnings, defined as amplitude decrease below 20% of the initial level, occurred in 37 muscles, but 22 of these (59%) did not have postoperative weakness (false positive). Positive predictive value was limited to 0.41. Of 113 muscles with no MEP warnings, 8 muscles developed postoperative weakness (false negative, 7%). Negative predictive value was 0.93. MEP responses were not elicited in 58 muscles (27%). By contrast, during clipping for unruptured aneurysms, MEP was recorded in 216 of 222 muscles (96%). Conclusion MEP monitoring has a limitation in predicting postoperative weakness in surgery for IMTs. False-positive and false-negative indices were abundant, with sensitivity and specificity of 0.65 and 0.83 in predicting postoperative weakness.

Object Regional blood flow is decreased in experimental models of chronic spinal cord compression, and the alteration presumably contributes to the development of myelopathy. Cilostazol (Otsuka Pharmaceuticals Co.), a selective Type III phosphodiesterase inhibitor, has been shown to be neuroprotective in cerebral hypoperfusion animal models and clinically effective in preventing the recurrence of cerebral infarction. To investigate the neuroprotective effect of cilostazol on cervical spondylotic myelopathy, the preventive effect against progressive motor dysfunction and the loss of anterior horn motor neurons were assessed using a chronic cord compression model in rats. Methods To produce chronic cervical cord compression in male Wistar rats, thin polyurethane sheets (3 × 5 × 0.7 mm) that gradually expand over 48–72 hours by absorbing water were implanted under the C5–6 laminae. In sham operations, the sheets were momentarily placed and then immediately removed. This model has been shown to reproduce characteristic features of clinical cervical myelopathy, with progressive motor disturbances after a latency period and insidious neuronal loss preceding the onset of symptoms. In the treatment group, cilostazol (30 mg/kg/day) was orally administered to the rats once a day, starting the day after surgery and continuing through the entire observation period of 25 weeks. In the control group, vehicle solution was administered under the same protocol. Changes in motor function were monitored by measuring bilateral forepaw grip strength and the duration of forced running on a treadmill. Twenty-five weeks after surgery, cervical spinal cords were examined histopathologically. Results Cilostazol preserved both forepaw grip strength and forced running capability. The drug also preserved anterior horn motor neurons in the C5–6 spinal cord segment, which diminished in number in the untreated chronic compression group. The drug decreased the number of TUNEL-positive apoptotic cells. Conclusions These results indicate that cilostazol is neuroprotective in the chronically compressed cervical cord and is potentially useful in the treatment of cervical spondylotic myelopathy.

Neurocutaneous melanosis (NCM) is a rare condition characterized by central nervous system melanocytic tumors associated with congenital melanocytic nevi. Phacomatosis pigmentovascularis (PPV) is an association of vascular nevus with pigmentary nevus. Aberrant maturation of neural crest-derived cells is considered to be related to pathogenesis in both conditions. However, association of NCM and PPV has not been reported to the best of our knowledge. Melanocytoma, which usually involves the leptomeninges or spinal cord, is extremely rare in the retroperitoneum. We present here a case of a patient with NCM, PPV, and melanocytic tumors in the spinal cord and retroperitoneum, which were treated surgically. A 40-year-old woman had a 2-year history of dysesthesia and weakness in the left leg. History included congenital giant blue nevus-like lesion in the trunk, a port-wine stain in the sacral area, and Caesarean section performed 8 years before, when diffuse pigmentation in the peritoneum was noted. Magnetic resonance (MR) imaging of the spine revealed an intramedullary tumor at T10 level with paramagnetic signal characteristics. The spinal cord tumor was totally removed, and the histological diagnosis was melanocytoma. Three months later, a left retroperitoneal mass with histological features of melanocytic tumor was removed. Neither tumors recurred and the patient stays ambulatory 4 years after the surgery. Multiple subtypes of melanocytic tumors with distinctive features of NCM and PPV can develop simultaneously, mimicking malignant melanoma. Gross total resection of each tumor, when indicated, is beneficial.

Study design Sham-operation-controlled animal study to assess alterations in blood flow in the spinal cord in a chronic compression model. Laboratory investigation. Objective Cervical myelopathy is a common cause of disability in elderly patients. Hypothesis was made that ischemia subsequent to the spinal cord compression plays an important role in the pathogenesis of the spinal cord dysfunction. This study was undertaken to assess alterations in the blood flow of the spinal cord under chronic compression in a rat model. Summary of background data Histologic study of spinal cord from patients with spondylotic myelopathy showed ischemic tissue changes. Experimentally, spinal cord hypoperfusion in combination with chronic spinal cord compression induced myelopathy in dogs. We previously showed that chronic compression of the spinal cord in rats produces gradual deterioration of mobility of the animals accompanied by cord tissue degeneration compatible with ischemic changes. Methods Chronic compression of the cervical spinal cord was implemented by implantation of a thin urethane polymer sheet under the C5-C6 laminae, which expands by absorbing tissue water over 48-72 hours. The control group underwent sham operation. Twelve weeks later, blood flow to the C3-C4 and C5-C6 spinal cord segments were measured by fluorescent microsphere methods. Results In the control group, the blood flow in the C5-C6 segment was larger than C3-C4 segment. In the compression group, the blood flow in the C5-C6 was significantly reduced compared to the C3-C4 segment. Conclusion Under chronic focal spinal cord compression, there was a decrease of the blood flow in the compressed segment in comparison to the rostral segment. Our data are compatible with the hypothesis that alteration in the spinal cord blood flow contributes to pathogenesis of myelopathy.

Spine surgery has made radical advancements in the last two decades and provision has expanded a great deal. The history of the technical development is briefly reviewed. To analyze trends in utilization and to assess the macroeconomic demand for spine surgery, the incidence of all spine surgery per capita is estimated referring to diverse statistical data from the USA, Korea and Japan. When compared internationally, there is a great disparity in the utilization of spine surgery, especially for fusion/instrumentation. Medico-socioeconomic conditions underlying the variations are discussed. Adequate surgeon training has to be supplied in a matched volume, and the number of surgeons to balance the need is estimated.

Cervical laminoplasty was developed as an alternative to cervical laminectomy for treatment of cervical myelopathy, in which hinges are created to lift the lamina. Various techniques of laminoplasty have since been developed after two prototype techniques: Hirabayashi's open-door laminoplasty and Kurokawa's spinous process splitting (double-door) laminoplasty. Several in vitro studies report superior biomechanical stability of the cervical spine after laminoplasty compared with laminectomy. In clinical situation, randomized control studies are scarce and superiority of one procedure over another is not uniformly shown. Lack of hard evidence supporting the purported advantages of laminoplasty over laminectomy, that is, reduced rate of postoperative instability and kyphosis development, while preserving range of motion (ROM), has been a weak selling point. Currently, laminoplasty is performed by majority of spine surgeons in Japan, but is rarely performed in the United States and Europe. Recent development in laminoplasty is preservation of muscle attachment, which enabled dynamic stabilization of the cervical spine by neck extensor muscles. After treatment with new laminoplasty techniques with active postoperative neck ROM exercises, postoperative instability, kyphosis, axial neck pain, and loss of ROM seems minimal. Well-designed clinical trials to show the effectiveness and long-term outcome of this surgical procedure are warranted.

A 40-year-old woman presented with a right petroclival meningioma compressing the brainstem and manifesting as a 6-month history of headache and gait difficulty. The patient underwent subtotal removal of the tumor via an anterior transpetrosal approach. The postoperative course was complicated by cerebrospinal fluid rhinorrhea, bacterial meningitis, and acute hemorrhagic rectal ulcer. The patient was discharged home in good condition after prolonged medical treatment. Four months after the surgery, the patient noted recurrence of gait difficulty. Magnetic resonance (MR) imaging of the brain showed enlargement of the ventricles and no residual brainstem compression. A ventriculoperitoneal shunt was placed, but the symptoms were unchanged. The shunt was removed 2 months later because of infection. The patient's gait gradually deteriorated, although repeat brain MR imaging showed no significant increase in ventricular size. Ten months after the initial surgery she became paraplegic. MR imaging of the thoracic spine revealed a large arachnoid cyst extending from C-6 to T-6. The patient underwent T2-4 laminectomy, partial removal of the cyst wall, and duraplasty, but no clinical improvement was observed. Preexisting long-tract signs and coincidental hydrocephalus confused the neurological findings and delayed detection of the spinal lesion in this case. Neurosurgeons should be alert to the possibilities of insidious spinal lesion if the patient has progressive neurological disorder which does not match the known cranial lesion.

Background Temporal bone chondroblastoma is a rare primary bone tumor that affects the floor of the middle cranial fossa. This tumor is known to have high recurrence rate after curettage, and wide resection is therefore recommended. However, the literature provides little information regarding long-term results after wide resection of temporal bone chondroblastoma. Methods Four cases of surgically treated temporal bone chondroblastoma underwent long-term follow-up. Results Four patients, 3 males and 1 female, with mean age of 34, were surgically treated at the neurosurgery department of Keio University Hospital. Two patients were treated for recurrent tumor and the other two for new disease. In all cases the tumor mainly involved the mandibular fossa with variable degree of infiltration into tympanic and petrous parts. The tumor was totally removed via zygomatic approach in all patients. In 3 patients, the mandibular condyle was removed to expose the tumor. These patients had temporary malocclusion and restricted motion postoperatively, which resolved within 3 to 12 months with conservative treatment. All patients have no recurrence to date with a mean follow-up period of 9 years. Conclusion Temporal bone chondroblastoma was removed totally with skull base surgical technique and no recurrence has occurred for 6 to 13 years postoperatively. We found that removal of the mandibular head does not cause permanent problems of mastication in patients with normal dentures.

OBJECTIVE AND IMPORTANCE Spinal accessory schwannomas unassociated with neurofibromatosis are very rare, and only 30 cases have been reported in the literature. To our knowledge, this is the first report of a spinal accessory schwannoma mimicking a tumor of the fourth ventricle. CLINICAL PRESENTATION A 50-year-old man presented with neck pain after being involved in a motor vehicle accident. There were no neurological deficits, but a computed tomographic scan revealed a large hypodense mass with punctuate calcifications in the fourth ventricle. The tumor exhibited low intensity on the T1-weighted magnetic resonance imaging scan and high intensity on the T2-weighted scan, and it showed inhomogeneous contrast enhancement. INTERVENTION The tumor was totally removed by a bilateral suboccipital craniectomy and C1 laminectomy. Dissection of the surgical specimen revealed that the tumor had originated from the left spinal accessory nerve. Histopathological examination confirmed the diagnosis of schwannoma. The patient experienced transient postoperative cerebellar ataxia but recovered completely. CONCLUSION Intracisternal-type spinal accessory schwannomas sometimes mimic a tumor of the fourth ventricle. Total surgical resection can be achieved with good outcome.

Scedosporium apiospermum, the asexual anamorph of Pseudallescheria boydii, is a ubiquitous saprophytic fungus that usually causes cutaneous/subcutaneous infection but may manifest as an invasive disease, often in immunocompromised hosts. Following an extensive literature review, we think that this case represents the first documented report of a primary infection of the spine in an immunocompetent patient. Despite extensive surgical debridement and itraconazole therapy, the patient died of multisystem organ failure of unknown etiology. Our case and three previously reported cases of P. boydii vertebral osteomyelitis highlight the importance of obtaining repeat cultures in patients with culture-negative vertebral osteomyelitis who fail to adequately respond to empiric standard antibacterial and/or antimycobacterial therapy. Combined surgical debridement and antifungal therapy have been required for eradication of P. boydii spinal infections in two previously reported immunocompromised patients, although the optimal antifungal regimen for this infection has not been established.

Two patients with giant intracavernous internal carotid artery (ICA) aneurysms were intolerant to balloon test occlusion of the ICA, and later developed spontaneous thrombosis of the aneurysm and the parent ICA without ischemic sequelae. Case 1: A 60-year-old female with a giant right intracavernous ICA aneurysm presented with right abducens nerve paresis. An unsuccessful extracranial-to-intracranial bypass graft operation was complicated by transient postoperative ophthalmoplegia. The patient did not tolerate balloon test occlusion of the right ICA after attempted bypass surgery, and was treated conservatively. The patient presented with acute onset of headache 3 years later. Case 2: A 50-year-old female with a giant right intracavernous ICA aneurysm presented with right abducens nerve paresis. The patient was managed conservatively after a positive balloon test occlusion of the right ICA. The patient suffered transient hypopituitarism and acute onset of headache 2 years later. Spontaneous thrombosis of the aneurysms and occlusion of the parent ICA were found in both patients. Neither had major hemispheric infarcts, but the first patient had asymptomatic infarcts, which were presumed to be thromboembolic in nature. Patients with intracavernous ICA aneurysms who have positive balloon test occlusions appear to develop tolerance to spontaneous and gradual occlusion of the ICA without significant sequelae. However, these patients have an increased risk of developing embolic infarctions. The role for anticoagulation and repeat hemodynamic tests remains unclear.

Regional blood flow is decreased in experimental models of chronic spinal cord compression, and the alteration presumably contributes to the development of myelopathy. Cilostazol (Otsuka Pharmaceuticals Co.), a selective Type III phosphodiesterase inhibitor, has been shown to be neuroprotective in cerebral hypoperfusion animal models and clinically effective in preventing the recurrence of cerebral infarction. To investigate the neuroprotective effect of cilostazol on cervical spondylotic myelopathy, the preventive effect against progressive motor dysfunction and the loss of anterior horn motor neurons were assessed using a chronic cord compression model in rats.To produce chronic cervical cord compression in male Wistar rats, thin polyurethane sheets (3 × 5 × 0.7 mm) that gradually expand over 48-72 hours by absorbing water were implanted under the C5-6 laminae. In sham operations, the sheets were momentarily placed and then immediately removed. This model has been shown to reproduce characteristic features of clinical cervical myelopathy, with progressive motor disturbances after a latency period and insidious neuronal loss preceding the onset of symptoms. In the treatment group, cilostazol (30 mg/kg/day) was orally administered to the rats once a day, starting the day after surgery and continuing through the entire observation period of 25 weeks. In the control group, vehicle solution was administered under the same protocol. Changes in motor function were monitored by measuring bilateral forepaw grip strength and the duration of forced running on a treadmill. Twenty-five weeks after surgery, cervical spinal cords were examined histopathologically.Cilostazol preserved both forepaw grip strength and forced running capability. The drug also preserved anterior horn motor neurons in the C5-6 spinal cord segment, which diminished in number in the untreated chronic compression group. The drug decreased the number of TUNEL-positive apoptotic cells.These results indicate that cilostazol is neuroprotective in the chronically compressed cervical cord and is potentially useful in the treatment of cervical spondylotic myelopathy.

Drill-induced heat has been suspected as a cause of tissue injury, and there are ample experimental data to substantiate the implication. However, no clinical results have been presented with measurement of temperature in the vicinity of neural structures during the actual spinal procedures. Using a thermocouple, temperature in the gutters drilled in the midline and the lateral margins of the lamina was monitored closely in 61 patients, who underwent the French-door style of cervical spino-laminoplasty. The drilling was performed intermittently for a duration of 5 or 10 seconds, using 3- or 5-mm diamond burrs with sufficient continuous cooling irrigation. The correlations between bone temperature elevation and postoperative sensorimotor symptoms were then analyzed. In the lateral gutters at the most cephalad level (typically C3), where the drilling was performed underneath an overlying bundle of muscle attached to C2's spinous process, the temperature rose significantly. This occurred even with 5-second drilling sessions. The average peak temperature was 44 °C at this level. At all other sites, the temperature was maintained below 40 °C. In three patients, transient neurological deficit developed postoperatively, which did not correlate with the incidence of bone temperature elevation. Intermittent drilling with sufficient irrigation can prevent thermal neuronal damage generated by high-speed drills. Drilling with small diamond burrs in deep and narrow spaces covered by overlying muscles predisposes to inadequate irrigation and thermal elevation. Continuous, protracted drilling without frequent irrigation may result in excessive heat generation and nerve injury.