Factors Affecting Cage Obliquity and the Relationship between Cage Obliquity and Radiological Outcomes in Oblique Lateral Interbody Fusion at the L4-L5 Level.

OBJECTIVE: This retrospective study investigated the factors that affect cage obliquity angle despite orthogonal maneuvers performed during oblique lateral interbody fusion (OLIF) and assessed the relationship between cage obliquity angle and radiological outcomes post-surgery. METHODS: Twenty-nine males who underwent L4-L5 OLIF for lumbar degenerative disease between 2019 and 2021 with a followup duration greater than 12 months were analyzed. Radiological parameters were measured including psoas muscle volume, total psoas area index (total psoas muscle area [cm2]/height squared [m2]), distance from the iliac artery to the origin of the psoas muscle (DIAPM), angle between the origin of the psoas muscle and the center of the vertebral disc (APCVD), iliac crest height, disc height, lumbar flexibility (lumbar flexion angle minus extension angle), cage location ratio, cage-induced segmental lumbar lordosis (LL) (postoperative index level segmental LL minus used cage angle), foraminal height changes, fusion grade. RESULTS: DIAPM, APCVD, iliac crest height, postoperative index level segmental LL, and cage-induced segmental LL were significantly correlated with OLIF cage obliquity angle. However, other radiological parameters did not correlate with cage obliquity. Based on multiple regression analysis, the predictive equation for the OLIF cage obliquity angle was 13.062-0.318×DIAPM+0.325×A PCVD+0.174×iliac crest height. The greater the cage obliquity, the smaller the segmental LL compared to the cage angle used. CONCLUSION: At the L4-L5 level, OLIF cage obliquity was affected by DIAPM, APCVD, and iliac crest height, and as the cage obliquity angle increases, LL agnle achievable by the used cage could not be obtained.

Long-Term Surgical Outcome of Indirect Bypass Surgery in Young Children With Moyamoya Disease.

BACKGROUND: The prognosis of moyamoya disease (MMD) in young children (younger than 4 years) is worse than that of older adults. The effectiveness of surgery is still inconclusive. OBJECTIVE: To evaluate long-term outcomes after indirect bypass in young children with MMD. METHODS: A total of 1417 MMD children underwent indirect bypass from August 1988 to October 2020. This study included 135 patients who were younger than 4 years at the time of surgery. The clinical features and surgical outcomes of these patients were assessed. We analyzed the long-term outcome of 102 children who were followed up for more than 5 years (mean: 18.8 years, range: 5-27.3 years). Cross-sectional analysis was performed to evaluate overall outcomes based on the Lansky Play Performance Scale (LPS). The annual risk of symptomatic stroke after surgery was calculated with a person-year method, and the event-free survival rate was evaluated using the Kaplan-Meier method. RESULTS: The overall clinical outcome was favorable (LPS ≥ 80) in 88% of the patients. The overall postoperative adverse event rate was 15%, including 1 death. At the last follow-up, 86% of patients who had seizures at diagnosis were seizure-free. During the follow-up, there were 3 symptomatic infarctions on the operated hemisphere (postoperative 3, 3, and 10 months each). There was no hemorrhagic event. The annual infarction rate was 0.16% per person-year. The 20-year event-free survival rates for symptomatic infarction were 97%. CONCLUSION: Indirect bypass could provide a satisfactory long-term outcome and prevent recurrent stroke in young children with MMD.

Hydration-induced rapid growth and regression after indirect revascularization of an anterior choroidal artery aneurysm associated with Moyamoya disease: A case report.

The prevalence of aneurysm formation in adults with Moyamoya disease (MMD) is higher than that in the general population. The treatment strategy is often individualized based on the patient's disease characteristics. A 22-year-old man was diagnosed with MMD after presenting a small thalamic intracerebral and subarachnoid hemorrhage in the quadrigeminal cistern. Cerebral angiography revealed a small aneurysm (2.42 mm) in the left anterior choroidal artery. Since the hemodynamics in the left hemisphere was compromised, an indirect bypass surgery was performed. The patient's condition deteriorated postoperatively because of poor perfusion of the internal carotid artery, and massive hydration was required. During neurocritical care, the aneurysm increased in size (5.33 mm). An observation strategy was adopted because of the distal aneurysmal location and the high risk involved. Subsequently, the patient recovered, and newly developed collateral flow appeared from the external carotid artery. Additionally, a dramatic size reduction of the aneurysm (1.51 mm) was noticed. Our case suggests that MMD-related dissecting aneurysms on a distal cerebral artery, which present a high risk of embolization, could be managed by indirectly reducing the hemodynamic burden. Massive hydration in such cases should be avoided or balanced to avoid the risk of rapid growth and aneurysm rupture.

Progression of Ossification of Posterior Longitudinal Ligament After Anterior Cervical Discectomy and Fusion in Military Patients Exposed to Minor Trauma.

Objective: Ossification of the posterior longitudinal ligament (OPLL) can progress even after cervical spine surgery and may cause neurological injury as a result of minor trauma. The purpose of this study was to investigate the preventive factors associated with OPLL progression after anterior cervical discectomy and fusion (ACDF), a procedure commonly performed in clinical practice. Methods: We retrospectively investigated 295 male soldiers who underwent ACDF surgery between 2012 and 2017. Patients who were followed up for >12 months using dynamic radiography and computed tomography (CT) were included in the study. Radiological parameters investigated included OPLL progression, C2-C7 angles on dynamic radiography, segmental angles, C2-C7 cervical sagittal vertical axis (C2-C7 SVA), and the T1 slope. These parameters were measured preoperatively and 1 year postoperatively. Results: A total of 49 patients were enrolled, and 10 patients were confirmed to have OPLL progression. Comparison between the OPLL progression and non-progression groups showed no statistically significant differences in pre- and postoperative cervical range of motion. However, statistically significant differences were observed in the postoperative neutral C2-C7 angle (progression -3.9°±6.4° vs. non-progression -13.4°±7.9°, p=0.001) and the SVA change (progression 5.8±7.9 mm vs. non-progression -3.7±6.3 mm, p=0.00). The cutoff values were -8.01° for the postoperative neutral C2-C7 angle and 1.4 mm for SVA changes. Conclusion: Increased SVA (>1.4 mm) and a small postoperative neutral C2-C7 angle (>-8.01°) 1 year after ACDF were associated with OPLL progression. It is important to be mindful of these factors during follow-up after ACDF, because additional surgical treatment may be necessary for OPLL progression due to neurological injury caused by minor trauma.

Clinical outcomes of pediatric cerebral cavernous malformation: an analysis of 124 consecutive cases.

OBJECTIVE: One-fourth of cerebral cavernous malformation (CCM) patients are children, but studies on these patients are scarce. This study aimed to identify the clinical presentation of pediatric CCM patients and to investigate clinical outcomes according to the treatment modalities applied on the basis of our institution's treatment strategy. METHODS: The authors performed a retrospective analysis of 124 pediatric CCM patients with a follow-up of more than 1 year from 2000 to 2019. They performed resection (n = 62) on lesions causing intractable seizure, rebleeding, or mass effect and observed the clinical courses of patients with lesions in deep or eloquent areas without persistent symptoms (n = 52). Radiosurgery (n = 10) was performed when the patient refused resection or strongly desired radiosurgery. The authors investigated the clinical characteristics, performance status (modified Rankin Scale [mRS] score), and rebleeding rate at the 1-year and last follow-up examinations and compared these among 3 groups classified on the basis of treatment applied. The authors evaluated seizure outcomes at the 1-year and last follow-up examinations for the surgery (n = 32) and observation (n = 17) groups. Finally, the authors drew cumulative incidence curves for the discontinuation of antiepileptic drugs (AEDs) for patients in the surgery (n = 30) and observation (n = 9) groups. RESULTS: The 3 groups showed slight differences in initial symptoms, lesion locations, and rates of recent hemorrhage. The proportion of patients with improved mRS score at the 1-year follow-up was significantly greater in the surgery group than in the other groups (67% of the surgery group, 52% observation group, and 40% radiosurgery group; p = 0.078), as well as at the last follow-up (73% surgery group, 54% observation group, and 60% radiosurgery group; p = 0.097). The surgery group also had the lowest rebleeding rate during the follow-up period (2% surgery group, 11% observation group, and 20% radiosurgery group; p = 0.021). At the 1-year follow-up, the proportion of seizure-free patients without AEDs was significantly higher in the surgery group than the observation group (88% surgery group vs 53% observation group, p < 0.001), and similar results were obtained at the last follow-up (91% surgery group vs 56% observation group, p = 0.05). The 5-year AED-free rates for the surgery and observation groups were 94% and 50%, respectively, on the cumulative incidence curve (p = 0.049). CONCLUSIONS: The clinical presentation of pediatric CCM patients was not significantly different from that of adult patients. Lesionectomy may be acceptable for pediatric CCM patients with indications of persistent seizures despite AED medications, rebleeding, and mass effects.

Leptomeningeal Spread at the Diagnosis of Glioblastoma Multiforme: A Case Report and Literature Review.

Approximately two-thirds of glioblastoma (GBM) patients progress to leptomeningeal spread (LMS) within two years. While 90% of LMS cases are diagnosed during the progression and/or recurrence of GBM (defined as secondary LMS), LMS presentation at the time of GBM diagnosis (defined as primary LMS) is very rare. 18F-fluorodeoxy glucose positron emission tomography computed tomography (18F-FDG PET/CT) study helps to diagnose the multifocal spread of the malignant primary brain tumor. Our patient was a 31-year-old man with a tumorous lesion located in the right temporal lobe, a wide area of the leptomeninges, and spinal cord (thoracic 5/6, and lumbar 1 level) involvement as a concurrent manifestation. After the removal of the right temporal tumor, the clinical status progressed rapidly, showing signs of increased intracranial pressure and hydrocephalus caused by LMS. He underwent a ventriculoperitoneal shunt a week after craniotomy. During management, progression of cord compression, paraplegia, bone marrow suppression related to radiochemotherapy, intercurrent infections, and persistent ascites due to peritoneal metastasis of the LMS through the shunt system was observed. The patient finally succumbed to the disease nine months after the diagnosis of simultaneous GBM and LMS. The overall survival of primary LMS with GBM in our case was nine months, which is shorter than that of secondary LMS with GBM. The survival period after the diagnosis of LMS did not seem to be significantly different between primary and secondary LMS. To determine the prognostic effect and difference between primary and secondary LMS, further cooperative studies with large-volume data analysis are warranted.

Recurrent Cervical Spontaneous Spinal Epidural Hematoma with Conservative Management: A Case Report.

Cervical spontaneous spinal epidural hematoma (CSSEH) is a rare condition that can be potentially fatal if not properly diagnosed and managed. While prompt surgical decompression and evacuation of the hematoma are generally considered as the first line of treatment, mild cases that were managed through observation and conservative treatment have been reported. Our patient was a 24-year-old man who experienced two CSSEH events 8 months apart, both of which were managed conservatively. This was a rare case of recurrent CSSEH in which recovery was achieved without surgical intervention. We believe conservative treatment with close observation may be effective in CSSEH patients presenting with mild neurologic symptoms who have a tendency towards spontaneous neurologic improvement.

Posterior Approach in C2-3 Disc Herniation: C1 Laminectomy, C2-3 Laminoplasty and Posterior Fixation in C2-3 Disc Herniation.

C2-3 disc herniation is rare and a definitive treatment of choice has not been established. The purpose of this case report is to suggest posterior approach as one of the best options. A 49-year-old man visited our clinic with a 7-year history of neck pain and occipital headache and a 2-month history of right arm pain. C2-3 intervertebral disc herniation of the central type was diagnosed on magnetic resonance imaging (MRI), and surgery was performed, including C1 laminectomy, C2-3 laminoplasty, and C2-3 posterior fixation. The posterior approach was used because the patient's neck was difficult to operate anteriorly. After 3 months postoperatively, MRI showed widened cerebrospinal fluid space at the C2-3 level. The visual analogue scale score for pain improved in the occipital area and right arm. However, the untouched protruded central disc, subjective weakness in right hand grasping, and numbness persisted. In conclusion, this case highlights posterior decompression and fixation as a good treatment of choice for decompression at the C2-3 level disc herniation, from where it is difficult to remove compressive lesions directly via the anterior corridor.

Clinical features and treatment strategy of paraspinal arteriovenous shunt (PAVS): a systematic review with individual participants data meta-analysis.

BACKGROUND: Because of the rarity of the disease, paraspinal arteriovenous shunt (PAVS) is not well recognized, and therapeutic options remain controversial. To introduce a rare disease of PAVS and demonstrate its etiology, clinical features, treatment options, and outcomes, we presented a case report and conducted a systematic review and individual participants data (IPD) meta-analysis. METHODS: Studies regarding on PAVS were integrated and IPD were obtained including patients' demographics, disease etiology, clinical and radiologic features, clinical courses and outcomes. Clinical manifestation and treatment outcomes were reviewed, and comparison analysis (cervical versus thoracolumbar) were performed. Further, logistic regression analyses were conducted to identify the poor prognostic factors (incomplete obliteration). RESULTS: Fifty-two articles were selected, and 88 patients enrolled. General and location-specific characteristics of PAVSs were identified: '3/4 of the isolated and 1/4 of the associated etiology', 'bruit, thrill, or murmur (cervical) and weakness (thoracolumbar) as common symptoms', '40% multiple feeders', and '22% intradural venous involvement'. Endovascular treatment was usually preferred (75%). Of 88 enrolled patients, 18 patients showed incomplete obliteration (20.5%). In multivariate analysis, 'etiologies of systematic genetic dysplasia (P = 0.031) and trauma (negatively, 0.038)' were significantly associated with incomplete obliteration. The parameters of 'multiple feeders (0.066)' and 'combined approach (negatively, 0.065)' are verified only in univariate analysis. CONCLUSION: General as well as location-specific characteristics of PAVS is successfully demonstrated. Approximately 20% of the incomplete obliteration is noted, and three potential poor prognostic factors are identified, namely, 'etiology of systematic genetic dysplasia (positive) and trauma (negative)', 'combined approach (negative), and 'multiple feeders'.

Clinicopathological Features of Primary Solitary Spinal Cord Tumors in Pediatric Patients : A 32-Year Single Institution Experience.

OBJECTIVE: Few studies exist on primary spinal cord tumors (PSCTs) in pediatric patients. The purpose of this study was to perform descriptive analysis and detailed survival analysis for PSCTs. METHODS: Between 1985 and 2017, 126 pediatric patients (male : female, 56 : 70) with PSCTs underwent surgery in a single institution. We retrospectively analyzed data regarding demographics, tumor characteristics, outcomes, and survival statistics. Subgroup analysis was performed for the intramedullary (IM) tumors and extradural (ED) tumors separately. RESULTS: The mean age of the participants was 6.4±5.04 years, and the mean follow-up time was 69.5±46.30 months. The most common compartment was the ED compartment (n=57, 45.2%), followed by the IM (n=43, 34.1%) and intradural extramedullary (IDEM; n=16, 12.7%) compartments. Approximately half of PSCTs were malignant (n=69, 54.8%). The most common pathologies were schwannomas (n=14) and neuroblastomas (n=14). Twenty-two patients (17.5%) died from the disease, with a mean disease duration of 15.8±15.85 months. Thirty-six patients (28.6%) suffered from progression, with a mean period of 22.6±30.81 months. The 10-year overall survival (OS) rates and progression-free survival (PFS) rates were 81% and 66%, respectively. Regarding IM tumors, the 10-year OS rates and PFS rates were 79% and 57%, respectively. In ED tumors, the 10-year OS rates and PFS rates were 80% and 81%, respectively. Pathology and the extent of resection showed beneficial effects on OS for total PSCTs, IM tumors, and ED tumors. PFS was affected by both the extent of removal and pathology in total PSCTs and ED tumors; however, pathology was a main determinant of PFS rather than the extent of removal in IM tumors. The degree of improvement in the modified McCormick scale showed a trend towards improvement in patients with IM tumors who achieved gross total removal (p=0.447). CONCLUSION: Approximately half of PSCTs were malignant, and ED tumors were most common. The most common pathologies were schwannomas and neuroblastomas. Both the pathology and extent of resection had a decisive effect on OS. For IM tumors, pathology was a main determinant of PFS rather than the extent of removal. Radical excision of IM tumors could be a viable option for better survival without an increased risk of worse functional outcomes.

Long-Term Outcomes and Sequelae Analysis of Intracranial Germinoma: Need to Reduce the Extended-Field Radiotherapy Volume and Dose to Minimize Late Sequelae.

PURPOSE: We aimed to refine the radiotherapy (RT) volume and dose for intracranial germinoma considering recurrences and long-term toxicities. MATERIALS AND METHODS: Total 189 patients with intracranial germinoma were treated with RT alone (n=50) and RT with upfront chemotherapy (CRT) (n=139). All cases were confirmed histologically. RT fields comprised the extended-field and involved-field only for primary site. The extended-field, including craniospinal, whole brain (WB), and whole ventricle (WV) for cranial field, is followed by involved-field boost. The median follow-up duration was 115 months. RESULTS: The relapses developed in 13 patients (6.9%). For the extended-field, cranial RT dose down to 18 Gy exhibited no cranial recurrence in 34 patients. In CRT, 74 patients (56.5%) showed complete response to chemotherapy and no involved-field recurrence with low-dose RT of 30 Gy. WV RT with chemotherapy for the basal ganglia or thalamus germinoma showed no recurrence. Secondary malignancy developed in 10 patients (5.3%) with a latency of 20 years (range, 4 to 26 years) and caused mortalities in six. WB or craniospinal field rather than WV or involved-field significantly increased the rate of hormone deficiencies, and secondary malignancy. RT dose for extended-field correlated significantly with the rate of hormone deficiencies, secondary malignancy, and neurocognitive dysfunction. CONCLUSION: De-intensifying extended-field rather than involved-field or total scheme of RT will be critical to decrease the late toxicities. Upfront chemotherapy could be beneficial for the patients with complete response to minimize the RT dose down to 30 Gy. Prospective trials focused on de-intensification of the extended-field RT are warranted.

Incidentally Found Intramuscular Hemangioma, Mimicking Traumatic Hematoma after Military Training: A Case Report.

This case report showed a young soldier complained of low back pain during military training. Intramuscular hematoma accompanied by the lumbar compression fracture was observed in computed tomography. However, the possibility of intramuscular tumors could not be ruled out through additional examinations, and thus surgically removed, and was diagnosed as cavernous hemangioma. This report is a rare and instructive case in which a hemangioma mimicked bleeding with the lumbar fracture.

Features of "false positive" unruptured intracranial aneurysms on screening magnetic resonance angiography.

BACKGROUND: Physicians can find it challenging to decide whether confirmative digital subtraction angiography (DSA) should be performed in patients who present with "suspicious small aneurysm-like structures" on magnetic resonance angiography (MRA). Factors associated with "false positive aneurysms on MRA" (FPAMs)," which are finally confirmed as negative on DSA, have rarely been reported. This study aimed to identify the clinical or radiologic clues indicative of FPAM on DSA. METHODS: Patients who had undergone DSA between 2016 and 2019 for suspicious aneurysm-like structures < 5 mm in size on MRA were enrolled. Patient demographics and the details regarding the geometry of the structures were retrospectively reviewed. Univariate and multivariate logistic regression analyses were conducted to identify the associated factors. Receiver operating characteristic curve analysis was performed to assess the clinical implications. RESULTS: Of the 107 suspicious structures, 46 were indicated as being false positive on DSA (42.96%). Location (positive on C7 and negative on C5-6 ICA) and lower dome to neck ratio were found to be significant parameters in the multivariate analysis. The dome to neck ratio threshold value was 0.99. CONCLUSION: Suspicious aneurysm-like structures located not on C5-6 but on C7 ICA and having wide neck morphologies (dome to neck ratio < 0.99) are highly likely to be negative on DSA.

Long-term outcome of large sylvian arachnoid cysts: the role of surgery has been exaggerated.

OBJECTIVE: The surgical indications for some arachnoid cysts (ACs) are controversial. While surgical procedures can be effective when an AC is a definite cause of hydrocephalus or papilledema, most ACs do not cause any symptoms or signs. Some surgeons perform several procedures to treat ACs because of their large size. The purpose of this study was to compare the long-term outcomes of Galassi type III ACs between surgery and nonsurgery groups. METHODS: The medical records of 60 patients diagnosed with sylvian ACs (Galassi type III) who visited Seoul National University Children's Hospital from July 1990 to March 2018 were analyzed. The authors compared the outcomes between those treated with surgery and those not treated with surgery. RESULTS: Of the 60 patients, 27 patients had no symptoms, 19 patients had vague symptoms and signs associated with ACs, and the remaining 14 patients had definite AC-related symptoms and signs. Thirty-eight patients underwent surgery, and 22 patients underwent observation. Some operations were accompanied by complications. Among the 33 patients in the surgery group, excluding 5 with hydrocephalus or papilledema, 8 patients needed 18 additional operations. However, there were no patients in the nonsurgery group who needed surgical intervention during the follow-up period (mean 67.5 months), although the size of the AC increased in 2 patients. Changes in AC size were not correlated with symptom relief. CONCLUSIONS: When patients with hydrocephalus or papilledema were excluded, there was no difference in the outcomes between the surgery and nonsurgery groups regardless of the size of the sylvian AC. Surgeons should be cautious when deciding whether to operate.

Long-Term Outcomes of Indirect Bypass for 629 Children With Moyamoya Disease: Longitudinal and Cross-Sectional Analysis.

Background and Purpose- In pediatric moyamoya disease, there are few reports on the efficacy of surgical intervention for stroke prevention. We evaluated the long-term outcomes of indirect bypass surgery on a relatively large number of children with moyamoya disease in a single center. Methods- From August 1988 to December 2012, 772 children underwent indirect bypass surgery. This study included 629 patients who were followed up for >5 years, excluding patients with moyamoya syndrome. The mean clinical follow-up duration was 12 years (range, 5-29 years). Cross-sectional analysis was performed based on either Karnofsky Performance Scale or Lansky Play Performance Scale to evaluate overall clinical outcomes and factors associated with unfavorable outcomes. To analyze the longitudinal effect of surgery, the annual risk of symptomatic infarction or hemorrhage on the operated hemisphere after indirect bypass surgery was calculated with a person-year method, and the event-free survival rate was evaluated using the Kaplan-Meier method. Results- The overall clinical outcome was favorable in 95% of the patients. The annual risks of symptomatic infarction and hemorrhage on the operated hemispheres were 0.08% and 0.04%, respectively. Furthermore, the 10-year event-free survival rates for symptomatic infarction and hemorrhage were 99.2% and 99.8%. Conclusions- Indirect bypass surgery could provide satisfactory long-term improvement in overall clinical outcome and prevention of recurrent stroke in children with moyamoya disease.

Preservation of the Arachnoid Membrane During Encephaloduroarteriosynangiosis Reduces Postoperative Complications without Undermining the Surgical Outcome in Pediatric Moyamoya Disease.

BACKGROUND: Encephaloduroarteriosynangiosis (EDAS) is a commonly used indirect revascularization operation method to treat pediatric patients with Moyamoya disease (MMD). Arachnoid dissection frequently has been performed during the EDAS operation to promote better revascularization. However, no studies have yet proven its surgical benefits. In this study, we investigated the impact of arachnoid preservation on the surgical outcome and postoperative complication by comparing pediatric patients with MMD who had the arachnoid membrane preserved during EDAS operation with those who had it dissected. METHODS: This was a retrospective cohort study based on a single surgeon's experience at a single institution. A total of 206 pediatric patients with MMD who underwent EDAS operation at Seoul National University Children's Hospital were recruited for the study. We compared the surgical outcome and the postoperation complication rate of these 2 groups. Furthermore, risk factors for postoperative complication were analyzed. RESULTS: The overall clinical outcome (P = 0.342) and the extent of revascularization of middle cerebral artery territories (P = 0.736) were not different between the arachnoid dissection group and the arachnoid preservation group. However, the postoperative infarction/hemorrhage rate was significantly greater in the arachnoid dissection group (P = 0.005). Arachnoid dissection (P = 0.011) and young age (<3 years old, P = 0.012) were significantly associated with increased risk of postoperative complications. CONCLUSIONS: Arachnoid preservation may help to reduce postoperative complications without decreasing the surgical outcome of EDAS. Furthermore, factors such as the patient's age should be taken into account when treating pediatric patients with MMD.

Epilepsy Surgery in 2019 : A Time to Change.

Epilepsy has been known to humankind since antiquity. The surgical treatment of epilepsy began in the early days of neurosurgery and has developed greatly. Many surgical procedures have stood the test of time. However, clinicians treating epilepsy patients are now witnessing a huge tide of change. In 2017, the classification system for seizure and epilepsy types was revised nearly 36 years after the previous scheme was released. The actual difference between these systems may not be large, but there have been many conceptual changes, and clinicians must bid farewell to old terminology. Paradigms in drug discovery are changing, and novel antiseizure drugs have been introduced for clinical use. In particular, drugs that target genetic changes harbor greater therapeutic potential than previous screening-based compounds. The concept of focal epilepsy has been challenged, and now epilepsy is regarded as a network disorder. With this novel concept, stereotactic electroencephalography (SEEG) is becoming increasingly popular for the evaluation of dysfunctioning neuronal networks. Minimally invasive ablative therapies using SEEG electrodes and neuromodulatory therapies such as deep brain stimulation and vagus nerve stimulation are widely applied to remedy dysfunctional epilepsy networks. The use of responsive neurostimulation is currently off-label in children with intractable epilepsy.

A Method of Untethering by Skipping the Area of Positive Responses on Electrical Stimulation During Surgery of Lumbosacral Lipomatous Malformation: "Hopping on a Stepping Stone".

OBJECTIVE: In complex lumbosacral lipomatous malformation or retethering, "crotch" dissection, an incision on the dura or lipoma at the site lateral to the lipoma-cord fusion line saving underlying roots, is often not easy. Attempts of this dissection in complex and obscured conditions may cause damage to the spinal cord or nerve roots. A method for caudal extension of untethering while positive areas on electrical stimulation were encountered during the crotch dissection of lumbosacral lipomatous malformation is described. METHODS: After thinning out the negative-response area just caudal to the positive-response area, a small perforation is made at the negative-response area skipping the positive-response area with probing the dissection direction through the subarachnoid space by an inside-out fashion. Subsequently, the procedure is continued caudally from the perforation site. RESULTS: Safe caudal extension of untethering is possible using this method. Illustrative operative photographs are shown. CONCLUSIONS: By using this method, safe untethering can be achieved avoiding root injuries in complicated lipomas such as chaotic or retethering cases.

Neurocognitive profile in children with arachnoid cysts before and after surgical intervention.

OBJECTIVES: Treatment indications for arachnoid cysts are not clear. Some surgeons take improvement in neurocognitive function into account as a surgical indication for arachnoid cysts. However, only a few studies have evaluated the relationship between arachnoid cysts and neurocognitive function. Furthermore, studies that analyze neurocognitive function as an effect of arachnoid cyst surgery are even rarer. The purpose of this study was to analyze the neurocognitive function scores of children with arachnoid cysts before and after surgery and to examine whether surgical treatment led to improved neurocognitive function. METHODS: From June 2009 to August 2012, data for 24 children diagnosed with arachnoid cysts who underwent surgery at Seoul National University Children's Hospital were analyzed. Pre-operative and post-operative cyst volume was assessed and neurocognitive function was tested using the Korean version of the Wechsler Intelligence Scale for Children-Revised (WISC-R) and the Bender-Gestalt Test (BGT). Comparison of pre- and post-operative profiles by laterality of the arachnoid cyst was performed. RESULTS: Patients had age-appropriate full-scale intelligent quotients (FSIQ), verbal IQ (VIQ), and performance IQ (PIQ) pre-operatively, which were maintained after surgery. Of the subtests, Block Design showed significant improvement post-operatively (p = 0.021). This means that visuo-spatial integration and mental construction abilities were improved after surgery. Patients with left or right arachnoid cysts did not show statistically significant changes in FSIQ, VIQ, or PIQ after surgery (110.21 versus 113.95, p = 0.307; 108.92 versus 111.54, p = 0.368; 107.88 versus 111.04, p = 0.152, respectively). Subanalysis showed that the pre- and post-operation VIQ mean scores of the patients with right arachnoid cysts were significantly higher (p < 0.054) than those of the patients with left arachnoid cysts, and there was no significant change after the surgery. INTERPRETATION: There was no significant association among cyst volume reduction, laterality, and clinical neurocognitive function improvement. The present findings indicate a limited role for surgical intervention in improving the intellectual abilities of children with arachnoid cysts.

Congenital Dermal Sinus and Limited Dorsal Myeloschisis: "Spectrum Disorders" of Incomplete Dysjuction Between Cutaneous and Neural Ectoderms.

BACKGROUND: The existence of tethering tracts in spinal dysraphism, other than congenital dermal sinus (CDS), has been recognized and has been summated into an integrated concept of limited dorsal myeloschisis (LDM). OBJECTIVE: To elucidate the underlying embryology of LDM in relation to CDS by focusing on the pathological features of special cases of tethering tracts. METHODS: Out of 389 spinal dysraphism patients who were operated on from 2010 to 2016, 5 patients who had tethering tracts composed of both CDS and LDM (or "probable LDM" if only fibrous tissue was found) were identified. Their clinical presentation, radiological images, operative findings, and pathology were thoroughly reviewed. RESULTS: Three nonsaccular-type patients harbored stalks in which the squamous epithelial lined sinus (CDS) was found in the distal portion, and fibroneural (LDM) or fibrous (probable LDM) tissue in the proximal part. Two patients had saccular lesions, and a stalk was found inside the sac, connecting a small pit on the skin to the spinal cord. The tracts were pathologically identical to a CDS. CONCLUSION: This study reports the coexistence of CDS and LDM (or probable LDM) components. These unique cases support the hypothesis that the CDS and LDM are among a spectrum of an anomaly that is caused by failure of complete dysjunction between cutaneous and neural ectoderms. Neurosurgeons should be aware of the possibility of coexisting "CDS" components in cases suggestive of LDM. In such cases, not only untethering but also meticulous removal of the squamous epithelium is critical.