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Toru Horikoshi, Arata Watanabe, Mikito Uchida and Hiroyuki Kinouchi

Object

Magnetic resonance imaging may show a fluid collection in the spinal epidural space of patients with spontaneous intracranial hypotension syndrome (SIHS), but the chronological changes remain unclear.

Methods

Brain and spine MR imaging findings were analyzed in 16 patients (9 women and 7 men, mean age 48.6 years) with SIHS before and after treatment.

Results

Diffuse dural enhancement was seen in 15 patients, and the epidural fluid collection in the spinal canal was clear in 15 and equivocal in 1. Symptoms disappeared after bed rest in 1 patient, and an epidural blood patch was performed in 15 patients, resulting in complete resolution of symptoms in 13. After the follow-up period (range 1–20 months, mean 5.0 months), 1 patient had persistent mild headache that gradually worsened in the afternoon, and another patient complained of heaviness of the eyes. Follow-up MR imaging demonstrated disappearance of the dural enhancement in all patients, but a fluid collection in the spinal canal remained in 4. Two of the 4 patients had persistent symptoms, but the other patients exhibited complete resolution of the symptoms.

Conclusions

An epidural blood patch is effective for sealing of CSF leaks, but the resolution of SIHS-related symptoms does not always imply complete eradication of the leakage.

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Kei Watanabe, Kazuhiro Hasegawa, Toru Hirano, Naoto Endo, Akiyoshi Yamazaki and Takao Homma

Object

The mechanism underlying cervical flexion myelopathy (CFM) is unclear. The authors report the results of anterior decompression and fusion (ADF) in terms of neurological status and radiographically documented status in young patients and discuss the pathophysiological mechanism of the entity.

Methods

Twelve patients underwent ADF in which autogenous iliac bone graft was placed. The fusion area was one segment in four cases, two segments in seven, and three segments in one. Neurological status, as determined by the Japanese Orthopaedic Association (JOA) score, radiographic findings, and intraoperative findings were evaluated. The mean follow-up period was 63.3 months (range 20–180 months).

Grip strength was significantly improved and sensory disturbances resolved completely. Intrinsic muscle atrophy, however, persisted in all patients at the final follow-up examination. Local kyphosis in the flexed-neck position at the fusion levels was corrected by surgery. Preoperative computerized tomography myelography revealed that the cord compression index, which was calculated by anteroposterior and transverse diameters of the spinal cord, decreased to 33 ± 6.2% in the flexed-neck position from 39.7 ± 9.9% in the extended-neck position. The anterior dura mater—spinal cord distance decreased to 1.9 ± 0.7 mm in the flexed-neck position from 4 ± 1.2 mm in extended-neck position. The posterior dura mater—spinal cord distance increased to 2.5 ± 1.1 mm in the flexed-neck position from 1.3 ± 0.5 mm in the extended-neck position.

Conclusions

Postoperative neurological status was improved in terms of grip strength, sensory disturbance, and JOA score, and local kyphosis in the flexed-neck position at the fusion levels was reduced and stabilized by ADF.

In most cases local kyphosis in the flexed-neck position was demonstrated at the corresponding disc level, as were cervical cord compression and decrease of the anterior wall of the dura mater—spinal cord distance in the flexed-neck position. Therefore, the contact pressure between the spinal cord and anterior structures (intact vertebral bodies and intervertebral discs) in the mobile and kyphotic segments was considered to contribute to the onset of CFM. The ADF-related improvement of the clinical symptoms, preventing kyphotic alignment in flexion and decreasing movement of the cervical spine, supports the idea of a contact pressure mechanism. Furthermore, short ADF performed only at the corresponding segments can preserve more mobile segments compared with posterior fusion. Thus, ADF should be the first choice in the treatment of CFM.

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Toru Watanabe, Yoshiho Honda, Yukihiko Fujii, Miyako Koyama and Ryuichi Tanaka

Object. The purposes of this study were to evaluate the serial changes in diffusion anisotropy of the brain, probably reflecting axonal function in brain-dead patients, and thus to explore the possibility of quantitatively estimating the risk of brain death.

Methods. Ten patients suffering from stroke with or without impending brain death and 10 healthy volunteers were studied using three-dimensional anisotropy contrast (3DAC) magnetic resonance (MR) axonography with the aid of a 1.5-tesla MR imaging system. To detect changes in the diffusion anisotropy of neural bundles, the corticospinal tract was evaluated.

Diffusion anisotropy of short axonal fibers decreased immediately after apparent brain death. Whereas the trichromatic coefficients of the corticospinal tract greatly diminished between 6 and 12 hours after apparent brain death, the coefficients of the corpus callosum and the optic radiation decreased in less time, that is, between 1 and 6 hours. The coefficients of these three bundles turned isotropic between 24 and 44 hours after apparent brain death.

Conclusions. Results of 3DAC MR axonography revealed that diffusion anisotropy of neural bundles diminished between 1 and 12 hours after the onset of apparent brain death, probably depending on the length of the bundles, and disappeared between 24 and 44 hours after the onset of brain death, which might reflect dynamic changes of axonal structure and indirectly herald axonal dysfunction. These findings seem to be greatly helpful in establishing an appropriate method to estimate the risk of brain death quantitatively and in forming the basis of future definitions of brain death.

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Keiichi Katsumi, Akiyoshi Yamazaki, Kei Watanabe, Toru Hirano, Masayuki Ohashi and Naoto Endo

Cervical radiculopathy of the C2–4 spinal nerves is a rare condition and is poorly documented in terms of clinical symptoms, hindering its detection during initial patient screening based on imaging diagnostics. The authors describe in detail the clinical symptoms and successful surgical treatment of a patient diagnosed with isolated C-4 radiculopathy. This 41-year-old man suffered from sleep disturbance because of pain behind the right ear, along the right clavicle, and at the back of his neck on the right side. The Jackson and Spurling tests were positive, with pain radiating to the area behind the patient's ear. Unlike in cases of radiculopathy involving the C5–8 spinal nerves, no loss of upper-extremity motor function was seen. Magnetic resonance imaging showed foraminal stenosis at the C3–4 level on the right side, and multiplanar reconstruction CT revealed a beak-type ossification of the posterior longitudinal ligament in the foraminal region at the same level. In the absence of intracranial lesions or spinal cord compressive lesions, the positive Jackson and Spurling tests and the C3–4 foraminal stenosis were indicative of isolated C-4 radiculopathy. Microscopic foraminotomy was performed at the C3–4 vertebral level and the ossified lesion was resected. The patient's symptoms completely resolved immediately after surgery. To the authors' knowledge, this report is the first to describe the symptomatic features of isolated C-4 radiculopathy, in a case in which the diagnosis has been confirmed by both radiological findings and surgical outcome. Based on this case study, the authors conclude that the characteristic symptoms of C-4 radiculopathy are the presence of pain behind the ear and in the clavicular region in the absence of upper-limb involvement.

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Arata Watanabe, Hiroyuki Kinouchi, Toru Horikoshi, Mikito Uchida and Keiichi Ishigame

Object

The subarachnoid space around the optic nerve in the orbit can be visualized using T2-weighted MR imaging with the fat-saturation pulse sequence. The optic nerve sheath (ONS) diameter can be estimated by measuring the outer diameter of the subarachnoid space. Dilated ONS is associated with idiopathic intracranial hypertension and hydrocephalus, and is believed to reflect increased intracranial pressure (ICP). The relationship between dilated ONS and ICP is unclear because of the difficulty in obtaining noninvasive measurements of ICP. The authors investigated the relationship between subdural pressure measured at the time of surgery and ONS diameter measured on MR images in patients with chronic subdural fluid collection.

Methods

Twelve patients underwent bur-hole craniostomy with continuous drainage for chronic subdural hematoma or hygroma in 2006. Orbital thin-slice fat-saturated MR images were obtained before and after surgery, and the ONS diameters were measured just behind the optic globe. Subdural pressure was measured using a manometer before opening of the dura mater.

Results

A significant correlation was found between the ONS diameter and the subdural pressure (correlation coefficient 0.879, p = 0.0036). The ONS diameter before surgery (6.1 ± 0.7 mm) was significantly reduced after surgery (4.8 ± 0.9 mm, p = 0.003; measurements are expressed as the mean ± standard deviation).

Conclusions

Increased ONS diameter measured on coronal orbital thin-slice fat-saturated T2-weighted MR images is a strong indicator of increased ICP, and helps to differentiate between passive subdural fluid collection due to brain atrophy and subdural hygroma with increased ICP.

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Nobuyasu Takeuchi, Toru Horikoshi, Hiroyuki Kinouchi, Arata Watanabe, Takashi Yagi, Kentaro Mitsuka and Nobuo Senbokuya

Object

The size of the subarachnoid space in the optic nerve sheath (ONS) on MR images is thought to reflect intracranial pressure. The diagnostic value of this space was investigated in patients with spontaneous intracranial hypotension (SIH) syndrome.

Methods

Coronal fat-saturated T2-weighted MRI of the orbit was performed in 15 patients with SIH fulfilling the diagnostic criteria for headache caused by low CSF pressure of the International Classification of Headache Disorders or the criteria for spontaneous spinal CSF leaks and intracranial hypotension. The size of the subarachnoid space in the ONS was measured in 2 slices behind the eyeballs. The images were compared before and after treatment. The CSF pressure was measured by lumbar puncture.

Results

Before treatment, the diameter of the ONS subarachnoid space ranged from 2.58 to 4.21 mm (mean 3.34 mm) and the thickness from 0 to 0.48 mm (mean 0.15 mm). Both measurements showed significant correlations with CSF opening pressure, and 8 patients had no CSF space before treatment. The size of CSF space increased in many patients after effective treatment.

Conclusions

Disappearance of the CSF space in the ONS was frequently observed in patients with SIH. This characteristic finding may be useful in the diagnosis of SIH as well as in the evaluation of treatment effectiveness.

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Toru Watanabe, Yoshiho Honda, Yukihiko Fujii, Miyako Koyama, Hitoshi Matsuzawa and Ryuichi Tanaka

Object. The purpose of this study was to assess how early wallerian degeneration in the corticospinal tracts of patients who had suffered from stroke was detected using three-dimensional anisotropy contrast (3D-AC) magnetic resonance (MR) axonography and to explore the possibility of predicting the prognosis for motor function in these patients.

Methods. Ten healthy volunteers and 16 stroke patients with hemiparesis were studied using MR images including 3D-AC MR axonography images obtained using a 1.5-tesla MR imaging system. The axonography was performed using an echoplanar imaging method. All patients underwent MR studies 2, 3, and 10 weeks after stroke onset. To detect wallerian degeneration, the diffusion anisotropy in the corticospinal tracts at the level of the upper pons was evaluated on axial images. These MR findings were compared with the patients' motor functions, which were classified according to the Brunnstrom criteria 12 weeks after the onset of stroke.

In all patients with poor recovery (Brunnstrom Stages I–IV), wallerian degeneration, which was demonstrated as a reduction in diffusion anisotropy on axonography images, could be observed in the corticospinal tracts; this degeneration was not found in patients with good recovery (Stages V and VI). Axonography could be used to detect degeneration between 2 and 3 weeks after stroke onset. On conventional T2-weighted MR images, hyperintense areas indicating wallerian degeneration were not detected until 10 weeks after stroke onset.

Conclusions. With the aid of 3D-AC MR axonography, wallerian degeneration can be detected in the corticospinal tracts during the early stage of stroke (2–3 weeks after onset), much earlier than it can be detected using T2-weighted MR imaging. The procedure of 3D-AC MR axonography may be useful in predicting motor function prognosis in stroke patients.

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Masaaki Yamamoto, Toru Serizawa, Yoshinori Higuchi, Osamu Nagano, Hitoshi Aiyama, Takao Koiso, Shinya Watanabe, Takuya Kawabe, Yasunori Sato and Hidetoshi Kasuya

OBJECTIVE

With the aging of the population, increasing numbers of elderly patients with brain metastasis (BM) are undergoing stereotactic radiosurgery (SRS). Among recently reported prognostic grading indexes, only the basic score for brain metastases (BSBM) is applicable to patients 65 years or older. However, the major weakness of this system is that no BM-related factors are graded. This prompted the authors to develop a new grading system, the elderly-specific (ES)–BSBM.

METHODS

For this IRB-approved, retrospective cohort study, the authors used their prospectively accumulated database comprising 3267 consecutive patients undergoing Gamma Knife SRS for BMs during the 1998–2016 period at the Mito GammaHouse. Among these 3267 patients, 1789 patients ≥ 65 years of age were studied (Yamamoto series [Y-series]). Another series of 1785 patients ≥ 65 years of age in whom Serizawa and colleagues performed Gamma Knife SRS during the same period (Serizawa series [S-series]) was used for validity testing of the ES-BSBM.

RESULTS

Two factors were identified as strongly impacting longer survival after SRS by means of multivariable analysis using the Cox proportional hazard model with a stepwise selection procedure. These factors are the number of tumors (solitary vs multiple: HR 1.450, 95% CI 1.299–1.621; p < 0.0001) and cumulative tumor volume (≤ 15 cm3 vs > 15 cm3: HR 1.311, 95% CI 1.078–1.593; p = 0.0067). The new index is the addition of scores 0 and 1 for these 2 factors to the BSBM. The ES-BSBM system is based on categorization into 3 classes by adding these 2 scores to those of the original BSBM. Each ES-BSBM category has 2 possible scores. For the category ES-BSBM 4–5, the score is either 4 or 5; for ES-BSBM 2–3, the score is either 2 or 3; and for ES-BSBM 0–1, the score is either 0 or 1. In the Y-series, the median survival times (MSTs, months) after SRS were 17.5 (95% CI 15.4–19.3) in ES-BSBM 4–5, 6.9 (95% CI 6.4–7.4) in ES-BSBM 2–3, and 2.8 (95% CI 2.5–3.6) in ES-BSBM 0–1 (p < 0.0001). Also, in the S-series, MSTs were, respectively, 20.4 (95% CI 17.2–23.4), 7.9 (95% CI 7.4–8.5), and 3.2 (95% CI 2.8–3.6) (p < 0.0001). The ES-BSBM system was shown to be applicable to patients with all primary tumor types as well as to those 80 years or older.

CONCLUSIONS

The authors found that the addition of the number of tumors and cumulative tumor volume as scoring factors to the BSBM system significantly improved the prognostic value of this index. The present study is strengthened by testing the ES-BSBM in a different patient group.

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Masaaki Yamamoto, Yoshinori Higuchi, Toru Serizawa, Takuya Kawabe, Osamu Nagano, Yasunori Sato, Takao Koiso, Shinya Watanabe, Hitoshi Aiyama and Hidetoshi Kasuya

OBJECTIVE

The results of 3-stage Gamma Knife treatment (3-st-GK-Tx) for relatively large brain metastases have previously been reported for a series of patients in Chiba, Japan (referred to in this study as the C-series). In the current study, the authors reappraised, using a competing risk analysis, the efficacy and safety of 3-st-GK-Tx by comparing their experience with that of the C-series.

METHODS

This was a retrospective cohort study. Among 1767 patients undergoing GK radiosurgery for brain metastases at Mito Gamma House during the 2005–2015 period, 78 (34 female, 44 male; mean age 65 years, range 35–86 years) whose largest tumor was > 10 cm3, treated with 3-st-GK-Tx, were studied (referred to in this study as the M-series). The target volumes were covered with a 50% isodose gradient and irradiated with a peripheral dose of 10 Gy at each procedure. The interval between procedures was 2 weeks. Because competing risk analysis had not been employed in the published C-series, the authors reanalyzed the previously published data using this method.

RESULTS

The overall median survival time after 3-st-GK-Tx was 8.3 months (95% CI 5.6–12.0 months) in the M-series and 8.6 months (95% CI 5.5–10.6 months) in the C-series (p = 0.41). Actuarial survival rates at the 6th and 12th post–3-st-GK-Tx months were, respectively, 55.1% and 35.2% in the M-series and 62.5% and 26.4% in the C-series (HR 1.175, 95% CI 0.790–1.728, p = 0.42). Cumulative incidences at the 12th post–3-st-GK-Tx, determined by competing risk analyses, of neurological deterioration (14.2% in C-series vs 12.8% in M-series), neurological death (7.2% vs 7.7%), local recurrence (4.8% vs 6.2%), repeat SRS (25.9% vs 18.0%), and SRS-related complications (2.3% vs 5.1%) did not differ significantly between the 2 series.

CONCLUSIONS

There were no significant differences in post–3-st-GK-Tx results between the 2 series in terms of overall survival times, neurological death, maintained neurological status, local control, repeat SRS, and SRS-related complications. The previously published results (C-series) are considered to be validated by the M-series results.

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Takuya Kawabe, Masaaki Yamamoto, Yasunori Sato, Shoji Yomo, Takeshi Kondoh, Osamu Nagano, Toru Serizawa, Takahiko Tsugawa, Hisayo Okamoto, Atsuya Akabane, Kazuyasu Aita, Manabu Sato, Hidefumi Jokura, Jun Kawagishi, Takashi Shuto, Hideya Kawai, Akihito Moriki, Hiroyuki Kenai, Yoshiyasu Iwai, Masazumi Gondo, Toshinori Hasegawa, Soichiro Yasuda, Yasuhiro Kikuchi, Yasushi Nagatomo, Shinya Watanabe and Naoya Hashimoto

OBJECTIVE

In 1999, the World Health Organization categorized large cell neuroendocrine carcinoma (LCNEC) of the lung as a variant of large cell carcinoma, and LCNEC now accounts for 3% of all lung cancers. Although LCNEC is categorized among the non–small cell lung cancers, its biological behavior has recently been suggested to be very similar to that of a small cell pulmonary malignancy. The clinical outcome for patients with LCNEC is generally poor, and the optimal treatment for this malignancy has not yet been established. Little information is available regarding management of LCNEC patients with brain metastases (METs). This study aimed to evaluate the efficacy of Gamma Knife radiosurgery (GKRS) for patients with brain METs from LCNEC.

METHODS

The Japanese Leksell Gamma Knife Society planned this retrospective study in which 21 Gamma Knife centers in Japan participated. Data from 101 patients were reviewed for this study. Most of the patients with LCNEC were men (80%), and the mean age was 67 years (range 39–84 years). Primary lung tumors were reported as well controlled in one-third of the patients. More than half of the patients had extracranial METs. Brain metastasis and lung cancer had been detected simultaneously in 25% of the patients. Before GKRS, brain METs had manifested with neurological symptoms in 37 patients. Additionally, prior to GKRS, resection was performed in 17 patients and radiation therapy in 10. A small cell lung carcinoma–based chemotherapy regimen was chosen for 48 patients. The median lesion number was 3 (range 1–33). The median cumulative tumor volume was 3.5 cm3, and the median radiation dose was 20.0 Gy. For statistical analysis, the standard Kaplan-Meier method was used to determine post-GKRS survival. Competing risk analysis was applied to estimate GKRS cumulative incidences of maintenance of neurological function and death, local recurrence, appearance of new lesions, and complications.

RESULTS

The overall median survival time (MST) was 9.6 months. MSTs for patients classified according to the modified recursive partitioning analysis (RPA) system were 25.7, 11.0, and 5.9 months for Class 1+2a (20 patients), Class 2b (28), and Class 3 (46), respectively. At 12 months after GKRS, neurological death–free and deterioration–free survival rates were 93% and 87%, respectively. Follow-up imaging studies were available in 78 patients. The tumor control rate was 86% at 12 months after GKRS.

CONCLUSIONS

The present study suggests that GKRS is an effective treatment for LCNEC patients with brain METs, particularly in terms of maintaining neurological status.