Intramedullary Schwannoma of the Spinal Cord: A Nationwide Analysis by the Neurospinal Society of Japan.

OBJECTIVE: This study was aimed to report the clinical characteristics of intramedullary schwannomas and discuss imaging findings and treatment strategies. METHODS: The inclusion criterion was consecutive patients with intramedullary schwannomas who were surgically treated at 8 centers between 2009 and 2020. Clinical characteristics included age, sex, clinical presentation, disease duration, and follow-up period. The modified McCormick scale was used to compare the preoperative and postoperative conditions. Pre- and postoperative magnetic resonance images (MRI) of each case were analyzed. RESULTS: The mean age of the total 11 patients at the operation was 50.2 years. The mean duration of the symptoms was 23 months, with limb paresthesia being the most common clinical presentation. The cervical spine was the most common localization level of the tumor in 6 cases. The mean follow-up duration was 49.4 months. Gross total resection (GTR) and subtotal resection (STR) was achieved in 9 and 2 cases, respectively. According to the modified McCormick scale at 6 months postoperatively, 7 cases (63.6%) had improved and 4 cases (36.3%) had unchanged grades. Typical MRI findings of the intramedullary schwannoma included ring-like enhancement, syringomyelia, cystic formation, intramedullary edema, and hemosiderin deposition. Gadolinium enhancement was homogenous in 8 cases (72.7%). The tumor margins were well demarcated in all cases. CONCLUSION: Intramedullary schwannoma should be considered when sharp margins and well-enhanced tumors are present at the cervical spine level and the initial symptoms are relatively mild, such as dysesthesia. When GTR cannot be achieved, STR for tumor decompression is recommended.

Correlation of active contact location with weight gain after subthalamic nucleus deep brain stimulation: a case series.

BACKGROUND: Weight gain (WG) is a frequently reported side effect of subthalamic deep brain stimulation; however, the underlying mechanisms remain unclear. The active contact locations influence the clinical outcomes of subthalamic deep brain stimulation, but it is unclear whether WG is directly associated with the active contact locations. We aimed to determine whether WG is associated with the subthalamic deep brain stimulation active contact locations. METHODS: We enrolled 14 patients with Parkinson's disease who underwent bilateral subthalamic deep brain stimulation between 2013 and 2019. Bodyweight and body mass index were measured before and one year following the surgery. The Lead-DBS Matlab toolbox was used to determine the active contact locations based on magnetic resonance imaging and computed tomography. We also created sweet spot maps for WG using voxel-wise statistics, based on volume of tissue activation and the WG of each patient. Fluorodeoxyglucose-positron emission tomography data were also acquired before and one year following surgery, and statistical parametric mapping was used to evaluate changes in brain metabolism. We examined which brain regions' metabolism fluctuation significantly correlated with increased body mass index scores and positron emission tomography data. RESULTS: One year after surgery, the body mass index increase was 2.03 kg/m2. The sweet spots for WG were bilateral, mainly located dorsally outside of the subthalamic nucleus (STN). Furthermore, WG was correlated with increased metabolism in the left limbic and associative regions, including the middle temporal gyrus, inferior frontal gyrus, and orbital gyrus. CONCLUSIONS: Although the mechanisms underlying WG following subthalamic deep brain stimulation are possibly multifactorial, our findings suggest that dorsal stimulation outside of STN may lead to WG. The metabolic changes in limbic and associative cortical regions after STN-DBS may also be one of the mechanisms underlying WG. Further studies are warranted to confirm whether dorsal stimulation outside of STN changes the activities of these cortical regions.

Chronic deep brain stimulation reduces cortical ß-γ phase amplitude-coupling in patients with Parkinson's disease.

We compared ß-γ phase amplitude coupling (PAC) before and one year after chronic deep brain stimulation (DBS) in patients with Parkinson's disease using EEG and observed significant post-operative reduction of PAC values. Our findings suggest that the reduction in PAC due to DBS can be observed after chronic stimulation, which is not a transient phenomenon just after the start of DBS.

Spinal rosette-forming glioneuronal tumor: A case report.

RATIONALE: Rosette-forming glioneuronal tumor (RGNT) is a rare tumor which has been first reported as the fourth ventricle tumor by Komori et al and is classified as a distinct clinicopathological entity by the WHO Classification of Tumors of the Central Nervous System as in 2007. Although RGNTs were reported to occur in both supratentorial and inflatentorial sites, only 4 case reports of spinal RGNT have been demonstrated. PATIENT CONCERNS: A 37-year-old female presenting with slowly progressing right-sided clumsiness. Cervical magnetic resonance imaging revealed a spinal intramedullary tumor between the C2 and C5 levels. DIAGNOSES: Pathological analysis showed unique biphasic cellular architecture consisting of perivascular pseudorosettes dominantly with few neurocytic rosettes and diffuse astrocytoma component. The tumor cells composed of perivascular pseudorosettes showed positivity for both synaptophysin and glial markers such as GFAP and Olig2. Therefore, the diagnosis of RGNT was made. INTERVENTIONS: Gross total resection of the tumor was achieved. No adjuvant chemotherapy nor radiotherapy was conducted after operation. OUTCOMES: At 2 years after the operation, no recurrence was observed. LESSONS: Although RGNT arising from the spinal cord is extremely rare, we need to consider the tumor as a differential diagnosis for intramedullary spinal cord tumors.

Cauda Equina Occupation Ratio as a New Imaging Parameter for the Evaluation of Spinal Dural Arteriovenous Fistulae.

BACKGROUND: Because spinal dural arteriovenous fistulae (SDAVF) are rare and their clinical presentation is nonspecific, they are often overlooked during diagnostic evaluations. Typical magnetic resonance imaging (MRI) findings are intramedullary T2-weighted signal hyperintensity and perimedullary flow voids. There are few reports on the characteristic signs of the cauda equina. We assessed the significance of a new imaging parameter, the cauda equina occupation ratio (CEOR), for the evaluation of SDAVF. METHODS: We retrospectively analyzed the clinical charts and radiological findings of 20 SDAVF patients treated at our institutions. We evaluated sagittal T2-weighted MRI scans and assessed the CEOR, the occupation ratio of the cauda equina compared to the sagittal diameter of the corresponding lumbar spinal canal. The controls were 21 age- and sex-matched subjects. RESULTS: Of the 20 SDAVF, 10 were at the thoracic and 10 at the lumbar spine. There was no significant difference between the preoperative CEOR and the spinal level of the fistulae or the neurological signs. On preoperative MRI scans, the mean CEOR was 56.0 ± 7.8; postoperatively, it was 37.1 ± 7.4 (P = 0.000). The preoperative CEOR was significantly larger in SDAVF patients than in the controls (P = 0.000); postoperatively, it was smaller than in the controls (P = 0.14). CONCLUSIONS: The preoperative CEOR was larger in patients with SDAVF than in the controls. It normalized after successful occlusion of the fistula. Our findings indicate that the CEOR is a useful parameter for the pre- and postoperative evaluation of SDAVF.

Estimation of the number of feeding arteries of spinal arteriovenous malformations by using three-dimensional digital subtraction angiography.

PURPOSE: Spinal angiography is the gold standard for evaluation or diagnosis of spinal arteriovenous malformations (AVMs). However, some feeding arteries might be overlooked when multiple feeders exist. This study aimed to retrospectively review cases of spinal intra-dural AVMs, which were identified by three-dimensional digital subtraction angiography (3D-DSA), and attempted to estimate the number of feeding arteries. METHODS: We retrospectively reviewed patients with spinal intra-dural AVMs who underwent 3D-DSA at Hokkaido University Hospital from January 2005 to December 2016. We selected 9 patients in whom we could obtain data of multi-planar reconstruction of 3D-DSA. We measured the computed tomography (CT) values of feeding arteries and draining veins. The CT values represented the averages of maximum CT values of 5 continuous axial slices. The ratio of the CT value of feeders to that of drainers (F/D ratio) was calculated. The correlation between the F/D ratio and the number of feeders was examined with Pearson's correlation coefficient. RESULTS: The average number of feeders was 2.3 (1-4), and the number of feeders was significantly positively correlated with the F/D ratio (r = 0.855, P = .003). CONCLUSIONS: We conclude that the number of feeding arteries of spinal intra-dural AVMs can be estimated by using the F/D ratio obtained from 3D-DSA. These slides can be retrieved under Electronic Supplementary Material.

Intraoperative Visualization of a Spinal Arachnoid Cyst Using Pyoktanin Blue.

BACKGROUND: Spinal arachnoid cysts (SACs) are filled with cerebrospinal fluid, and they include the arachnoid membrane, making it difficult to distinguish the walls of the cyst from the arachnoid membrane and excise the cyst as a lump. Here we report a technique for the intraoperative visualization of SACs, involving the use of pyoktanin blue. METHODS: Four patients with spinal intradural arachnoid cysts underwent total excision of the cysts between October 2016 and April 2017. In 1 case, magnetic resonance imaging revealed the cyst clearly, but in the other cases, the cysts were unclear. All cysts were injected with 1% pyoktanin blue (Wako Pure Chemical Industries, Osaka, Japan) diluted 500 times with physiological saline before excision. When it was difficult to distinguish the cyst from the normal arachnoid membrane, 1% pyoktanin blue diluted 1000 times with physiological saline was injected into both the cyst and the subarachnoid space, and the spread of the stain was observed. RESULTS: The cysts were better visualized after pyoktanin blue injection than before injection. When it was difficult to distinguish the cyst from the normal arachnoid space, pyoktanin blue injection was useful for judging the cyst space. There were no perioperative complications, and the patients' symptoms improved partially or completely after treatment. CONCLUSIONS: Our technique of pyoktanin blue injection into SACs could make their excision easy and safe.

Ten-Year Retrospective Study on the Management of Spinal Arteriovenous Lesions: Efficacy of a Combination of Intraoperative Digital Subtraction Angiography and Intraarterial Dye Injection.

BACKGROUND: The goal of treatment for spinal arteriovenous lesions is to completely obliterate the shunt. In our institution, intraoperative digital subtraction angiography and intraarterial injection of contrast agent have been used to accurately identify the site of arteriovenous shunts. We describe the intraoperative digital subtraction angiography and intraarterial dye injection procedures and how they may improve surgical outcomes. METHODS: We retrospectively investigated 22 patients with intradural arteriovenous lesions (n = 19) or spinal dural arteriovenous fistulas (n = 3). A microcatheter was used during the procedures to avoid catheter migration. RESULTS: There were 29 procedures performed. To support the surgical procedures, indigo carmine was used 17 times and indocyanine green was used 12 times. There were no complications associated with these procedures. The indocyanine green procedure required a lower concentration of dye in the artery than in the vein to clarify the shunt point and visualized complex lesions more clearly. These methods allowed surgeons to orientate the complex vessel structure. CONCLUSIONS: Intraoperative digital subtraction angiography and intraarterial dye injection are useful tools for management of spinal arteriovenous lesions.

[Utility of Intraoperative Catheter Myelography during Intrathecal Baclofen Pump Implantation:Report of 2 Cases].

We report two patients in whom the intrathecal baclofen(ITB)catheter was located in the subdural space, although we had confirmed good outflow of spinal fluid from the spinal catheter. Patient 1 was a woman in her 30s with spastic quadriplegia due to subarachnoid hemorrhage. An ITB pump was implanted, and a good outflow of spinal fluid from the spinal catheter was observed during the surgery. Postoperatively, her spasticity did not improve. Catheter myelography revealed that the spinal catheter was located in the subdural space. Using intraoperative catheter myelography, we corrected the position of the catheter. Patient 2 was a man in his 20s diagnosed with adrenoleukodystrophy. An ITB therapy was performed to improve his spastic gait. Intraoperative catheter myelography showed that the spinal catheter was located in the subdural space, although there was good outflow of spinal fluid from the catheter. Our experience suggests that the outflow of spinal fluid alone should not be used to determine the location of the spinal catheter. Intraoperative catheter myelography is useful for the correct placement of the spinal catheter in the subarachnoid space.

Health-related quality of life in patients with spinal dural arteriovenous fistulae.

Neurological improvement in patients with spinal dural arteriovenous fistulae (SDAVF) is often partial even after adequate treatment. While treatment outcomes have been evaluated primarily on the basis of the postoperative changes in neurological deficits, outcome measures should also reflect the patient-reported outcome (PRO). We conducted a health-related quality of life (HRQOL) survey in 52 SDAVF patients; 33 (63.5%) completed the short-form 36 Health Survey (SF-36) questionnaire. They were 25 males and 8 females ranging in age from 47 to 85 years (mean age 70.0 years). The mean follow-up period was 95.6 months. We analyzed the completed questionnaires and examined the clinical factors associated with their HRQOL. After treatment, gait- and micturition disturbances persisted in 31 (93.9%) and 31 (93.9%) of our patients; 26 (78.8%) reported chronic leg pain. The SF-36 scores of treated SDAVF patients were significantly lower than the national average of 50 for all 8 sub-items in the questionnaire. The scores for physical functioning (PF) and role-physical (RP) were particularly low. With the exception of bodily pain (BP), there was a significant negative correlation between the Aminoff-Logue scale (ALS) scores for gait- and micturition and the sub-item scores. The score for BP showed a significant positive correlation with the scores for the 7 other SF-36 sub-items. The HRQOL of treated SDAVF patients was lower than the national average with respect to both physical and mental aspects. Persistent post-treatment pain and gait- and micturition disturbances were responsible for their lower HRQOL.

Surgical Outcome of Children and Adolescents with Tethered Cord Syndrome.

STUDY DESIGN: Retrospective cohort study. PURPOSE: To compare long-term results of surgery with the outcomes of symptomatic and asymptomatic tethered cord syndrome (TCS) in children and adolescents and to assess the surgery duration for those with TCS. OVERVIEW OF LITERATURE: Pediatric patients with TCS continue to pose significant diagnostic and management challenges. METHODS: We retrospectively analyzed the outcomes of 31 patients (16 males, 15 females) with TCS, including 21 with lumbosacral lipoma. All were surgically treated between 1989 and 2015. They were divided into symptomatic and asymptomatic TCS groups. The results of the treatment were summarized and analyzed using a non-parametric Mann-Whitney U test. RESULTS: Nineteen patients had symptomatic TCS and 12 had asymptomatic TCS. Patients had a median age of 34 months (range, 0-201 months). The median follow-up period was 116 months (range, 7-223 months). Of the 19 symptomatic TCS patients, preoperative deficits improved after surgery in two (10.5%) and remained stable in 17 (89.5%) patients. One of the 12 asymptomatic TCS (8.3%) patients showed an exacerbated illness after surgery, and one in 11 patients remained stable (11.7%). There were significant differences in monthly age at surgery, preoperative bowel and bladder dysfunction, neurological function, presence/absence of clean intermittent catheterization introduction, and presence/absence of motor disorder at final follow-up (all p<0.05). In the univariate analysis, the presence/absence of preoperative bowel and bladder dysfunction, and symptoms were strongly associated with the risk of children and adolescents with TCS (p<0.05). CONCLUSIONS: Early accurate diagnosis and adequate surgical release might lead to successful outcomes in children and adolescents with TCS. Surgical untethering is a safe and effective method for treatment of children with TCS.

Clinical Factors for Prognosis and Treatment Guidance of Spinal Cord Astrocytoma.

STUDY DESIGN: Retrospective study. PURPOSE: To obtain information useful in establishing treatment guidelines by evaluating baseline clinical features and treatment outcomes of patients with spinal cord astrocytoma (SCA). OVERVIEW OF LITERATURE: The optimal management of SCA remains controversial, and there are no standard guidelines. METHODS: The study included 20 patients with low-grade and 13 with high-grade SCA surgically treated between 1989 and 2014. Patients were classified according to the extent of surgical resection. Survival was assessed using Kaplan-Meier plots and compared between groups by log-rank tests. Neurological status was defined by the modified McCormick scale and compared between groups by Mann-Whitney U tests. RESULTS: Surgical resection was performed for 19 of 20 low-grade (95%) and 10 of 13 high-grade (76.9%) SCA patients. Only nine patients (27.3%) underwent gross total resection, all of whom had low-grade SCA. Of all patients, 51.5% showed deteriorated neurological status compared to preoperative baseline. Median overall survival was significantly longer for low-grade SCA than that (91 months, 78% at 5 years vs. 15 months, 31% at 5 years; p=0.007). Low-grade SCA patients benefited from more aggressive resection, whereas high-grade SCA patients did not. Multivariate analysis revealed histology status (hazard ratio [HR], 0.30; 95% confidence interval [CI], 0.09-0.98; p<0.05) and postoperative neurological status (HR, 0.12; CI, 0.02-0.95; p<0.05) as independent predictors of longer overall survival. Adjuvant radiotherapy had no significant impact on survival rate. However, a trend for increased survival was observed with radiation cordotomy (RCT) in high-grade SCA patients. CONCLUSIONS: Aggressive resection for low-grade and RCT may prolong survival. Preservation of neurological status is an important treatment goal. Given the low incidence of SCA, establishing strong collaborative, interdisciplinary, and multi-institutional study groups is necessary to define optimal treatments.

[A Dumbbell-Type Thoracic Spinal Lipoma: A Case Report].

Spinal lipomas are rare, accounting for less than 1% of all spinal tumors. Most are associated with spinal dysraphism. Spinal lipomas without spinal dysraphism are uncommon;they are typically subpial tumors. Some tumors are located both inside and outside the dura mater (so-called "dumbbell-type"). Herein, we report a patient with a dumbbell-type thoracic spinal lipoma. A man in his 50's complained of progressive gait disturbance, dysesthesia in his left leg, and hyperesthesia in his right leg. His symptoms were worsened by exercise. CT and MRI revealed a thoracic spinal lipoma extending from the spinal cord to the intervertebral foramen at the Th 6-8 level. He underwent partial tumor removal and untethering. Postoperatively he reported gradual symptom abatement. Dumbbell-type spinal lipomas are very rare. Besides partial removal of the tumor, untethering should be considered when symptoms are associated with tethering of the spinal cord.

Development of a nonintermediate-incision ventriculoperitoneal shunt procedure using a nasogastric feeding tube for infant patients with hydrocephalus: technical note.

Intermediate incisions are considered necessary to pass a catheter tube from the head to the abdomen in ventriculo-peritoneal (VP) shunting via a frontal bur hole. However, an intermediate incision can sometimes become dehiscent, resulting in CSF leakage or infection of the shunt system in the early period after shunt implantation, particularly in infant patients. In this article, the authors describe a novel method of VP shunt insertion that does not require an intermediate incision. This nonintermediate-incision VP shunt procedure was performed in 3 infant patients with hydrocephalus and was not associated with any complications. This method can eliminate the intermediate incision, which is a disadvantage of VP shunt insertion via a frontal bur hole.

Long-term outcomes after surgical and endovascular treatment of spinal dural arteriovenous fistulae.

PURPOSE: To examine the validity of our treatment strategy for spinal dural arteriovenous fistulae (SDAVF), based on the treatment results and the long-term outcome. METHODS: This study included 50 SDAVF patients (38 men, 12 women, mean age 63.2 years) with progressive myelopathy. The treatment strategy involved embolization as the initial management tool and surgery if embolization was considered unsuitable. Their medical records were evaluated to identify the treatment results and functional outcomes. The mean follow-up period was 81.2 months (range 27-184 months). RESULTS: Complete obliteration was achieved in 22 (71.0%) of 31 embolized patients and in 18 of 19 (94.7%) operated patients. The initial success rate was significantly lower in embolized than operated patients. At the last follow-up, 33 of the 50 patients (66%) manifested improved gait and 16 (32%) improved micturition. The activity of daily living (ADL) was improved in 33 (66%). When we compared the rates of functional improvement at the last follow-up, there was no significant difference between patients treated initially by embolization or surgery. CONCLUSIONS: The long-term outcomes in SDAVF patients treated by multidisciplinary management with first-line embolization were comparable to those in earlier surgical series. However, our results were unable to demonstrate the superiority of endovascular embolization to surgical treatment for SDAVF. For the purpose of justifying endovascular embolization as a first-line treatment for SDAVF, it will be necessary to show further improvement in both the initial treatment success and the complication rates.

A Survey of Chronic Pain Due to Spinal Dural Arteriovenous Fistulae.

BACKGROUND: Chronic pain due to spinal dural arteriovenous fistulae (SDAVF) during follow-up is a serious issue because it can affect patients' quality of life. The severity of posttreatment chronic leg pain in patients with SDAVF is unclear. OBJECTIVE: To investigate the prevalence, severity, and characteristics of chronic leg pain in patients with SDAVF and to examine the clinical factors associated with chronic pain. METHODS: We conducted a survey of their chronic posttreatment leg pain in 49 SDAVF patients. It consisted of a numeric rating scale and a neuropathic pain symptom inventory (NPSI). Of the 49 patients, 32 (65.3%) completed the questionnaire. There were 24 males and 8 females whose mean age was 69.1 years. The mean follow-up period was 86.3 months. RESULTS: Chronic leg pain was reported by 26 (81.3%) of 32 patients; 14 experienced pain before treatment and 12 had new-onset posttreatment pain. The pain was reported as moderate to severe by 21 (80.8%) of 26 patients; the mean numeric rating scale and NPSI scores were 6.0 ± 2.3 and 17.4 ± 10.3, respectively. The NPSI subscores were significantly higher for spontaneous pain and paresthesia/dysesthesia than for paroxysmal pain. We found no significant clinical factors related to chronic posttreatment pain; on magnetic resonance imaging scans we identified spinal cord atrophy in 8 patients with chronic pain. CONCLUSION: Most of our SDAVF patients reported moderate to severe chronic leg pain characterized by spontaneous pain and paresthesia/dysesthesia. Spinal cord atrophy on magnetic resonance imaging scans was a characteristic in patients with chronic pain.

Neurovascular bundle decompression without excessive dissection for tarsal tunnel syndrome.

Tarsal tunnel syndrome (TTS) is an entrapment neuropathy of the posterior tibial nerve and its branches in the tarsal tunnel. We present our less invasive surgical treatment of TTS in 69 patients (116 feet) and their clinical outcomes. The mean follow-up period was 64.6 months. With the patient under local anesthesia we use a microscope to perform sharp dissection of the flexor retinaculum and remove the connective tissues surrounding the posterior tibial nerve and vessels. To prevent postoperative adhesion and delayed neuropathy, decompression is performed to achieve symptom improvement without excessive dissection. Decompression is considered complete when the patient reports intraoperative symptom abatement and arterial pulsation is sufficient. The sensation of numbness and/or pain and of foreign substance adhesion was reduced in 92% and 95% of our patients, respectively. In self-assessments, 47 patients (68%) reported the treatment outcome as satisfactory, 15 (22%) as acceptable, and 7 (10%) were dissatisfied. Of 116 feet, 4 (3%) required re-operation, initial decompression was insufficient in 2 feet and further decompression was performed; in the other 2 feet improvement was achieved by decompression of the distal tarsal tunnel. Our surgical method involves neurovascular bundle decompression to obtain sufficient arterial pulsation. As we use local anesthesia, we can confirm symptom improvement intraoperatively, thereby avoiding unnecessary excessive dissection. Our method is simple, safe, and without detailed nerve dissection and it prevents postoperative adhesion.

Usefulness of 11C-methionine-positron emission tomography for the diagnosis of progressive multifocal leukoencephalopathy.

Progressive multifocal leukoencephalopathy (PML) is a subacute demyelinating disease of the brain caused by the JC virus that occurs mainly in immunocompromised patients. The prognosis is very poor. As the lesion looks like non- specific leukoencephalopathy, making a diagnosis at the early stage is very difficult. We report three PML cases in which there was a mismatch between (11)C-methionine-positron emission tomography (MET-PET) uptake and (18)F-fluorodeoxyglucose-positron emission tomography (FDG-PET) uptake. All three cases demonstrated the hyper-uptake of MET around the white matter lesions and hypo-uptake of FDG inside the lesions. We speculate that the infection had ended inside the white matter lesions of these patients, while JC virus infection was ongoing around the lesions, resulting in the increase of methionine metabolism, and the glucose metabolism was reduced or intermediate because inflammatory cells infiltrate PML lesions rarely. Two patients who were diagnosed and treated with mefloquine while the JC virus was at a low level in the cerebrospinal fluid are still alive. We suggest the usefulness of MET-PET for the early diagnosis of PML and early treatment with mefloquine.

A case of cervical juxtafacet cyst with extensive rim enhancement on Gd-DTPA MRI.

The authors reported a case of cervical juxtafacet cyst with extensive rim enhancement on gadolinium-diethylenetriamine pentaacid magnetic resonance imaging. Operative finding revealed the epidural space around the mass filled with abundant venous plexus. Histological examination demonstrated that cyst wall was composed of the well-vascularized fibrous connective tissue with some inflammatory changes. We speculate that extensive rim enhancement of juxtafacet cyst may be attributed not only to the chronic inflammatory changes of cyst wall, but to engorged venous plexus within the widened epidural space.