Adult isocitrate dehydrogenase-mutant brainstem glioma: illustrative case

BACKGROUND

Adult brainstem gliomas are rare entities that demonstrate heterogeneous biology and appear to be distinct from both their pediatric counterparts and adult supratentorial gliomas. Although the role of histone 3 mutations is being increasingly understood in this disease, the effect of isocitrate dehydrogenase (IDH) mutations remains unclear, largely because of limited data.

OBSERVATIONS

The authors present the case of a 29-year-old male with an IDH1-mutant, World Health Organization grade III anaplastic astrocytoma in the dorsal medulla, and they provide a review of the available literature on adult IDH-mutant brainstem glioma. The authors have amassed a cohort of 15 such patients, 7 of whom have survival data available. Median survival is 56 months in this small cohort, which is similar to that for IDH wild-type adult brainstem gliomas.

LESSONS

The authors' work reenforces previous literature suggesting that the role of IDH mutation in glioma differs between brainstem and supratentorial lesions. Therefore, the authors advocate that adult brainstem gliomas be studied in terms of major molecular subgroups (including IDH mutant) because these gliomas may exhibit fundamental differences from each other, from pediatric brainstem gliomas, and from adult supratentorial gliomas.

Increased glycemic variability associated with a poor 30-day functional outcome in acute intracerebral hemorrhage

The authors analyzed the association between the standard deviation or the coefficient of variation in the glucose value, strong independent indexes for determining glycemic variability, and the prognosis of intracerebral hemorrhage. They found that glycemic variability may be associated with a poor outcome in intracerebral hemorrhage.

Therapeutic outcomes of transsphenoidal surgery in pediatric patients with craniopharyngiomas: a single-center study

OBJECTIVE The aim of this study was to analyze the outcomes of transsphenoidal surgery (TSS) in a single-center clinical series of pediatric craniopharyngioma patients treated with gross-total resection (GTR). METHODS The authors retrospectively reviewed the surgical outcomes for 65 consecutive patients with childhood craniopharyngiomas (28 girls and 37 boys, mean age 9.6 years) treated with TSS (45 primary and 20 repeat surgeries) between 1990 and 2015. Tumors were classified as subdiaphragmatic or supradiaphragmatic. Demographic and clinical characteristics, including extent of resection, complications, incidence of recurrence, pre- and postoperative visual disturbance, pituitary function, and incidence of diabetes insipidus (DI), as well as new-onset obesity, were analyzed and compared between the primary surgery and repeat surgery groups. RESULTS Of the 45 patients in the primary surgery group, 26 (58%) had subdiaphragmatic tumors and 19 had supradiaphragmatic tumors. Of the 20 patients in the repeat surgery group, 9 (45%) had subdiaphragmatic tumors and 11 had supradiaphragmatic tumors. The only statistically significant difference between the 2 surgical groups was in tumor size; tumors were larger (mean maximum diameter 30 mm) in the primary surgery group than in the repeat surgery group (25 mm) (p = 0.008). GTR was accomplished in 59 (91%) of the 65 cases; the GTR rate was higher in the primary surgery group than in the repeat surgery group (98% vs 75%, p = 0.009). Among the patients who underwent GTR, 12% experienced tumor recurrence, with a median follow-up of 7.8 years, and recurrence tended to occur less frequently in primary than in repeat surgery patients (7% vs 27%, p = 0.06). Of the 45 primary surgery patients, 80% had deteriorated pituitary function and 83% developed DI, whereas 100% of the repeat surgery patients developed these conditions. Among patients with preoperative visual disturbance, vision improved in 62% but worsened in 11%. Visual improvement was more frequent in primary than in repeat surgery patients (71% vs 47%, p < 0.001), whereas visual deterioration was less frequent following primary surgery than repeat surgery (4% vs 24%, p = 0.04). Among the 57 patients without preoperative obesity, new-onset postoperative obesity was found in 9% of primary surgery patients and 21% of repeat surgery patients (p = 0.34) despite aggressive resection, suggesting that hypothalamic dysfunction was rarely associated with GTR by TSS in this series. However, obesity was found in 25% of the repeat surgery patients preoperatively due to prior transcranial surgery. Although there were no perioperative deaths, there were complications in 12 cases (18%) (6 cases of CSF leaks, 3 cases of meningitis, 2 cases of transient memory disturbance, and 1 case of hydrocephalus). Postoperative CSF leakage appeared to be more common in repeat than in primary surgery patients (20% vs 4.4%, p = 0.2). CONCLUSIONS The results of TSS for pediatric craniopharyngioma in this case series suggest that GTR should be the goal for the first surgical attempt. GTR should be achievable without serious complications, although most patients require postoperative hormonal replacement. When GTR is not possible or tumor recurrence occurs after GTR, radiosurgery is recommended to prevent tumor regrowth or progression.

Head shape at age 36 months among children with and without a history of positional skull deformation

OBJECTIVE In this study, the authors examined head shape through age 36 months for children with and without a history of positional plagiocephaly and/or brachycephaly (PPB). METHODS Infants with PPB (cases) were identified through a craniofacial clinic at the time of diagnosis. Infants without diagnosed PPB were identified through a participant registry. Clinician ratings of 3D cranial images were used to confirm the presence or absence of PPB. The cohort included 235 case infants (diagnosed PPB, confirmed with 3D imaging), 167 unaffected controls (no diagnosed PPB, no deformation detected), and 70 affected controls (no diagnosed PPB, discernible skull deformation). Participants were seen in infancy (age 7 months, on average) and again at ages 18 and 36 months. At each visit, automated 3D measures of skull deformation quantified posterior flattening and generated an absolute asymmetry score. The authors also used automated 2D measures to approximate overall asymmetry (approximate oblique cranial length ratio) and calculate the cephalic index. They used linear regression to compare cases to unaffected controls and to compare affected versus unaffected controls on all measures. They also calculated the proportion of children in each group with "persistent PPB," defined as one or more head shape measures above the 95th percentile relative to unaffected controls at 36 months. RESULTS Head shape became more rounded and symmetric for children with and without PPB, particularly between infancy and age 18 months. However, children with PPB continued to show greater skull deformation and asymmetry than unaffected controls at age 36 months. These differences were large in magnitude, ranging from 1 to 2 standard deviations (SDs), and in most (85.6%) of the cases, there was evidence of persistent PPB at 36 months. Similarly, although differences were more modest (i.e., 0.26-0.94 SD), affected controls continued to exhibit skull deformation on most measures relative to unaffected controls and approximately 30% had persistent PPB. Within the case group, head shape at 36 months was similar for untreated patients with PPB and for those who received helmet treatment and for patients with and without a history of torticollis. CONCLUSIONS Although head shape continues to improve, children with a history of skull deformation in infancy continue to exhibit measureable cranial flattening and asymmetry through age 36 months.

Surgical management of incidentally discovered diffusely infiltrating low-grade glioma

OBJECTIVE Occasionally, diffusely infiltrating low-grade gliomas (LGGs) are identified as incidental findings in patients who have no signs or symptoms that can be ascribed to the tumors. The diagnosis of incidental, asymptomatic LGGs has become more frequent due to the vast increase in access to medical imaging technology. While management of these lesions remains controversial, early surgery has been suggested to improve outcome. The authors set out to identify and review the characteristics and surgical outcomes of patients who underwent surgical intervention for incidental LGG. METHODS All cases of LGG surgically treated between 2004 and 2016 at the authors' institution were analyzed to identify those that were discovered incidentally. Patients with incidentally discovered LGGs were identified, and their cases were retrospectively reviewed. An "incidental" finding was defined as an abnormality on imaging that was obtained for a reason not attributable to the glioma, such as trauma, headache, screening, or research participation. Kaplan-Meier analysis was performed to determine actuarial rates of overall survival, progression-free survival, and malignant progression-free survival. RESULTS In 34 (6.8%) of 501 adult patients who underwent surgery for LGG, the tumors were discovered incidentally. Headache (26%, n = 9) and screening (21%, n = 7) were the most common indications for brain imaging in this group. Four of these 34 patients had initial biopsy after the tumor was identified on imaging. In 5 cases, the patients opted for immediate resection; the remaining cases were managed with a "watch-and-wait" approach, with intervention undertaken only after radiological or clinical evidence of disease progression. The mean duration of follow-up for all 34 cases was 5 years. Twelve patients (35.3%) had disease progression, with an average time to progression of 43.8 months (range 3-105 months). There were 5 cases (14.7%) of malignant progression and 4 deaths (11.8%). Oligodendroglioma was diagnosed in 16 cases (47%) and astrocytoma in 15 (44%). Twenty-five patients (74%) had IDH1 mutation and demonstrated prolonged survival. Only 2 patients had mild surgery-related complications, and 16 patients (47%) developed epilepsy during the course of the disease. CONCLUSIONS In this retrospective analysis of cases of incidentally discovered LGGs, the tumors were surgically removed with minimal surgical risk. In patients with incidental LGGs there is improved overall survival relative to median survival for patients with symptomatic LGGS, which is likely attributable to the underlying favorable biology of the disease indicated by the presence of IDH1 mutation in 74% of the cases.

A proposal for a new classification of complications in craniosynostosis surgery

OBJECTIVE Complications have been used extensively to facilitate evaluation of craniosynostosis practice. However, description of complications tends to be nonstandardized, making comparison difficult. The authors propose a new pragmatic classification of complications that relies on prospective data collection, is geared to capture significant morbidity as well as any "near misses" in a systematic fashion, and can be used as a quality improvement tool. METHODS Data on complications for all patients undergoing surgery for nonsyndromic craniosynostosis between 2010 and 2015 were collected from a prospective craniofacial audit database maintained at the authors' institution. Information on comorbidities, details of surgery, and follow-up was extracted from medical records, anesthetic and operation charts, and electronic databases. Complications were defined as any unexpected event that resulted or could have resulted in a temporary or permanent damage to the child. RESULTS A total of 108 operations for the treatment of nonsyndromic craniosynostosis were performed in 103 patients during the 5-year study period. Complications were divided into 6 types: 0) perioperative occurrences; 1) inpatient complications; 2) outpatient complications not requiring readmission; 3) complications requiring readmission; 4) unexpected long-term deficit; and 5) mortality. These types were further subdivided according to the length of stay and time after discharge. The overall complication rate was found to be 35.9%. CONCLUSIONS The proportion of children with some sort of complication using the proposed definition was much higher than commonly reported, predominantly due to the inclusion of problems often dismissed as minor. The authors believe that these complications should be included in determining complication rates, as they will cause distress to families and may point to potential areas for improving a surgical service.

Factors influencing outcomes of the treatment of positional plagiocephaly in infants: a 7-year experience

OBJECTIVE Following institution of the Back to Sleep Campaign, the incidence of sudden infant death syndrome decreased while the prevalence of positional skull deformation increased dramatically. The management of positional deformity is controversial, and treatment recommendations and outcomes reporting are variable. The authors reviewed their institutional experience (2008-2014) with the treatment of positional plagiocephaly to explore factors associated with measured improvement. METHODS A retrospective chart review was conducted with risk factors and treatment for positional head shape deformity recorded. Univariate and multivariate analyses were used to assess the impact of these variables on the change in measured oblique diagonal difference (ODD) on head shape surface scanning pre- and posttreatment. RESULTS A total of 991 infants aged less than 1 year were evaluated for cranial positional deformity in a dedicated clinical program. The most common deformity was occipital plagiocephaly (69.5%), followed by occipital brachycephaly (18.4%) or a combination of both deformities (12.1%). Recommended treatment included repositioning (RP), physical therapy (PT) if indicated, or orthotic treatment with a customized cranial orthosis (CO) according to an age- and risk factor-dependent algorithm that the authors developed for this clinic. Of the 991 eligible patients, 884 returned for at least 1 follow-up appointment. A total of 552 patients were followed to completion of their treatment and had a full set of records for analysis: these patients had pre- and posttreatment 2D surface scanner evaluations. The average presenting age was 6.2 months (corrected for prematurity for treatment considerations). Of the 991 patients, 543 (54.8%) had RP or PT as first recommended treatment. Of these 543 patients, 137 (25.2%) transitioned to helmet therapy after the condition did not improve over 4-8 weeks. In the remaining cases, RP/PT had already failed before the patients were seen in this program, and the starting treatment recommendation was CO. At the end of treatment, the measured improvements in ODD were 36.7%, 33.5%, and 15.1% for patients receiving CO, RP/PT/CO, and RP/PT, respectively. Univariate analysis showed that sex, race, insurance, diagnosis, sleep position preference, torticollis history, and multiple gestation were not significantly associated with magnitude of ODD change during treatment. On multivariate analysis, corrected age at presentation and type of treatment received were significantly associated with magnitude of ODD change. Orthotic treatment corresponded with the largest ODD change, while the RP/PT group had the least change in ODD. Earlier age at presentation corresponded with larger ODD change. CONCLUSIONS Earlier age at presentation and type of treatment impact the degree of measured deformational head shape correction in positional plagiocephaly. This retrospective study suggests that treatment with a custom CO can result in more improvement in objective measurements of head shape.

Increased blood cell phosphatidylserine exposure and circulating microparticles contribute to procoagulant activity after carotid artery stenting

OBJECTIVE Phosphatidylserine (PS) is a major component of the inner leaflet of membrane bilayers. During cell activation or apoptosis, PS is externalized to the outer membrane, providing an important physiological signal necessary for the release of the microparticles (MPs) that are generated through the budding of cellular membranes. MPs express PS and membrane antigens that reflect their cellular origin. PS exposure on the cell surface and the release of MPs provide binding sites for factor Xa and prothrombinase complexes that promote thrombin formation. Relatively little is known about the role of PS exposure on blood cells and MPs in patients with internal carotid artery (ICA) stenosis who have undergone carotid artery stenting (CAS). The authors aimed to investigate the extent of PS exposure on blood cells and MPs and to define its role in procoagulant activity (PCA) in the 7 days following CAS. METHODS The study included patients with ICA stenosis who had undergone CAS (n = 70), matched patients who had undergone catheter angiography only (n = 30), and healthy controls (n = 30). Blood samples were collected from all patients just before the procedure after an overnight fast and at 2, 6, 24, 48, and 72 hours and 7 days after the CAS procedure. Blood was collected from healthy controls after an overnight fast. Phosphatidylserine-positive (PS+) MPs and blood cells were analyzed by flow cytometry, while PCA was assessed with clotting time analysis, purified coagulation complex assays, and fibrin formation assays. RESULTS The authors found that levels of PS+ blood cells and PS+ blood cell-derived MPs (platelets and platelet-derived MPs [PMPs], neutrophils and neutrophil-derived MPs [NMPs], monocytes and monocyte-derived MPs [MMPs], erythrocytes and erythrocyte-derived MPs [RMPs], and endothelial cells and endothelial cell-derived MPs [EMPs]) were increased in the 7 days following the CAS procedure. Specifically, elevation of PS exposure on platelets/PMPs, neutrophils/NMPs, and monocytes/MMPs was detected within 2 hours of CAS, whereas PS exposure was delayed on erythrocytes/RMPs and EMPs, with an increase detected 24 hours after CAS. In addition, PS+ platelets/PMPs peaked at 2 hours, while PS+ neutrophils/NMPs, monocytes/MMPs, and erythrocytes/RMPs peaked at 48 hours. After their peak, all persisted at levels above baseline for 7 days post-CAS. Moreover, the level of PS+ blood cells/MPs was correlated with shortened coagulation time and significantly increased intrinsic and extrinsic Xase, thrombin generation, and fibrin formation. Pretreatment of blood cells with lactadherin at their peak time point after CAS blocked PS, resulting in prolonged coagulation times, decreased procoagulant enzyme activation, and fibrin production. CONCLUSIONS The results of this study suggest that increased exposure of PS on blood cells and MPs may contribute to enhanced PCA in patients with ICA stenosis who have undergone CAS, explaining the risk of perioperative thromboembolic complications in these patients. PS on blood cells and MPs may serve as an important biomarker for predicting, and as a pivotal target for monitoring and treating, acute postoperative complications after CAS. ■ CLASSIFICATION OF EVIDENCE Type of question: association; study design: prospective cohort trial; evidence: Class I.

Financial burden associated with the residency match in neurological surgery

OBJECTIVE Application for a residency position in neurosurgery is a highly competitive process. Visiting subinternships and interviews are integral parts of the application process that provide applicants and programs with important information, often influencing rank list decisions. However, the process is an expensive one that places significant financial burden on applicants. In this study, the authors aimed to quantify expenses incurred by 1st-year neurosurgery residents who matched into a neurosurgery residency program in 2014 and uncover potential trends in expenses. METHODS A 10-question survey was distributed in partnership with the Society of Neurological Surgeons to all 1st-year neurosurgery residents in the United States. The survey asked respondents about the number of subinternships, interviews, and second looks (after the interview) attended and the resultant costs, the type of program match, preferences for subinternship interviews, and suggestions for changes they would like to see in the application process. In addition to compiling overall results, also examined were the data for differences in cost when stratifying for region of the medical school or whether the respondent had contact with the program they matched to prior to the interview process (matched to home or subinternship program). RESULTS The survey had a 64.4% response rate. The mean total expenses for all components of the application process were US $10,255, with interview costs comprising the majority of the expenses (69.0%). No difference in number of subinternships, interviews, or second looks attended, or their individual and total costs, was seen for applicants from different regions of the United States. Respondents who matched to their home or subinternship program attended fewer interviews than respondents who had no prior contact with their matched program (13.5 vs 16.4, respectively, p = 0.0023) but incurred the same overall costs (mean $9774 vs $10,566; p = 0.58). CONCLUSIONS Securing a residency position in neurosurgery is a costly process for applicants. No differences are seen when stratifying by region of medical school attended or contact with a program prior to interviewing. Interview costs comprise the majority of expenses for applicants, and changes to the application process are needed to control costs incurred by applicants.

Impact of transfer status on hospitalization cost and discharge disposition for acute ischemic stroke across the US

OBJECT In this study, the authors used information provided in the Nationwide Inpatient Sample (NIS) to study the impact of transferring stroke patients from one facility to a center where they received some form of active stroke intervention (intravenous tissue plasminogen activator, thrombectomy, or a combination of both therapies). METHODS Patient demographic characteristics and hospital factors obtained from the 2008-2010 acute stroke NIS data were analyzed. Discharge disposition, hospitalization cost, and mortality were the dependent variables studied. Univariate analysis and multivariate binary logistic regression analysis were performed. Data analysis focused on the cohort of acute stroke patients who received some form of active intervention (55,913 of 1,311,511 patients in the NIS). RESULTS When overall outcome was considered, transferred patients had a significantly higher number of other-than-routine (OTR, i.e., other than discharge to home without home health care) discharge dispositions (p < 0.0001). In multivariate regression analysis including pertinent patient and hospital factors, transfer-in patients had significantly worse OTR discharge disposition (p < 0.0001, odds ratio [OR] 2.575, 95% CI 2.341-2.832). Mean hospitalization cost including an intervention was $70,325.11 for direct admissions and $97,546.92 for transferred patients. Transfer from another facility (p < 0.001, OR 1.677, 95% CI 1.548-1.817) was associated with higher hospitalization cost. CONCLUSIONS The study showed that hospital cost for acute stroke intervention is significantly higher for a transferred patient than for a direct admission. Moreover, the frequency of OTR discharge was significantly higher among transferred patients than direct admissions. Future strategies should focus on ways and means of transporting patients appropriately and directly to stroke centers.

Signal changes of the alar ligament in a healthy population: a dispositional or degenerative consequence?

OBJECT The alar ligaments (ALs) are vital for stabilizing the craniocervical junction. In terms of morphology, their appearance varies and is visible on MRI. Dark signal of the AL on proton-density (PD)-weighted images is generally considered the norm, but the etiology of frequently observed signal hyperintensities is poorly understood. Using spectral fat suppression, signal hyperintensities can be differentiated into fat- and nonfat-related hyperintensities (NFH). Although signal hyperintensities have no evident association with whiplash-associated disorder, age-related degeneration has often been theorized. Therefore, this study investigates the signal intensities of the ALs on 3.0-T MRI with special reference to age. Expanding thereon, the authors investigated the relationship between signal hyperintensities and patient characteristics, such as height, weight, and sex. METHODS Sixty-six healthy volunteers were scanned using 3.0-T PD-weighted MRI, including spectral fat suppression of the craniocervical junction. The study population was separated into 2 groups (old vs young) using 2 approaches: dichotomization at the median age (40.0 years) and the calculated threshold (28.5 years) using receiver operating characteristics (ROC). The AL was independently characterized with respect to continuity, course, shape, signal intensity, and graduation of homogeneity by 2 experienced neuroradiologists. Signal intensity was differentiated into fat-related hyperintensity and NFH. Univariate and multivariate logistic regression models were employed to investigate the relationship between patient characteristics and signal intensities. RESULTS Two different AL patterns were observed: inhomogeneous (33.3%) and homogeneous (66.7%). The latter pattern was mostly surrounded by a small dark rim (56.8%). Fat could be identified in 15.9% of all ALs (21 of 132 patients), and NFH was identified in 17.4% of all ALs (23 of 132 patients). Here, 28.5 years was the preferred threshold, demonstrating a relatively high sensitivity for dichotomizing the population based on the ROC of NFH. The most relevant factor for having NFH was being older than the calculated threshold (odds ratio [OR] 3.420, p = 0.051). Fat-related hyperintensities occurred significantly more frequently in men than women (OR 0.110 and p = 0.007 for women; OR 9.075 and p = 0.007 for men). Height was the second most significant factor: for every 1-cm increase, the odds of having fat lesions increased by approximately 10% (OR 1.102; p = 0.017). CONCLUSIONS This study shows that AL signal hyperintensities are substantially influenced by age, sex, and height in healthy individuals. Regarding fat-related hyperintensities, the most relevant factors proved to be sex and height. The odds of detecting NFH increased almost significantly after a relatively young age (> 28.5 years) and were remarkably more frequent in individuals older than 28.5 years. The authors caution presumptions equating signal alterations with age-related deterioration. Instead, they suggest that dispositional factors such as sex and height are more relevant in the AL constitution. Signal alterations in ALs naturally occur in healthy symptom-free individuals, underscoring the importance of cautiously interpreting such lesions on posttraumatic MRI scans.

Impact of body mass index on cerebellar tonsil position in healthy subjects and patients with Chiari malformation

OBJECT

It is unclear if there is a relationship between Chiari malformation Type I (CM-I) and body mass index (BMI). The aim of this study was to identify the relationship between BMI and cerebellar tonsil position in a random sample of people.

METHODS

Cerebellar tonsil position in 2400 subjects from a cohort of patients undergoing MRI was measured. Three hundred patients were randomly selected from each of 8 age groups (from 0 to 80 years). A subject was then excluded if he or she had a posterior fossa mass or previous posterior fossa decompression or if height and weight information within 1 year of MRI was not recorded in the electronic medical record.

RESULTS

There were 1310 subjects (54.6%) with BMI records from within 1 year of the measured scan. Of these subjects, 534 (40.8%) were male and 776 (59.2%) were female. The average BMI of the group was 26.4 kg/m(2), and the average tonsil position was 0.87 mm above the level of the foramen magnum. There were 46 subjects (3.5%) with a tonsil position ≥ 5 mm below the level of the foramen magnum. In the group as a whole, there was no correlation (R(2) = 0.004) between BMI and cerebellar tonsil position.

CONCLUSIONS

In this examination of 1310 subjects undergoing MRI for any reason, there was no relationship between BMI and the level of the cerebellar tonsils or the diagnosis of CM-I on imaging.

Aggressive transsphenoidal resection of tumors invading the cavernous sinus in patients with acromegaly: predictive factors, strategies, and outcomes

OBJECT

Cavernous sinus (CS) invasion is the most important preoperative predictor of remission in the surgical treatment of growth hormone-producing pituitary adenomas. The purpose of this study was to evaluate the effectiveness of an aggressive technique for removal of tumors invading the CS in patients with acromegaly.

METHODS

The authors retrospectively reviewed the cases of 150 consecutive patients with acromegaly who underwent primary transsphenoidal surgery in 2010 and 2011. The authors reviewed preoperative Knosp grade, intraoperative findings, histology of the medial wall of the CS, and surgical outcome according to the current consensus criteria for acromegaly.

RESULTS

Cavernous sinus invasion was identified in 55 patients (36.7%): definite CS involvement by the tumor was observed under direct vision in 41 patients (74.5%), while invasion was histologically verified in 39 patients (70.9%). Invasion increased in frequency with the higher Knosp grade but was observed in 14.4% (13 of 90) of Grade 0 and 1 tumors. Overall, the remission rate fulfilling stringent criteria was 84.7% (127 of 150). Although CS invasion was significantly associated with an unfavorable outcome (p < 0.0001), remission was achieved in 69.1% (38 of 55) of patients with invasion. No major complications occurred in this series.

CONCLUSIONS

Cavernous sinus invasion is the most significant, independent predictor of unfavorable outcome. Confirmation of invasion requires direct observation within the CS regardless of the microscope or endoscope used. Particularly in cases in which only the medial wall is involved, histological verification is always necessary to detect the occult invasion. Direct removal of the invading tumor, by sharp excision of the medial wall of the CS, is effective and safe and increases the chance of remission.