Objective : Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy and can be effectively treated via surgery. However, the predictors for outcomes after surgery require further elucidation. CTS was diagnosed by nerve conduction study (NCS), and its severity was classified using a scale from 0 to 6 (Bland's classification). This study aimed to identify the utility of the palmar stimulation in a nerve conduction study in patients with severe CTS (Grades 5 and 6) and the relationship between Bland's grading score and the clinical outcome.

  Methods : A total of 67 patients (96 hands) diagnosed with CTS (Grade 3 and more) between April 2014 and April 2018 underwent surgery at our hospital, among which 33 patients (47 hands) were diagnosed with severe CTS (Grade 5 and 6) and were included in this study. NCS was performed initially and 6 months after the surgery, particularly focusing on the median palmar compound muscle action potential (CMAP) amplitude and the sensory nerve action potential (SNAP) amplitude ; furthermore, axonal degeneration was evaluated using the palmar CMAP/SNAP amplitudes. A simple questionnaire with a five-point rating scale was also administered 6 months after surgery, and improvements in the grading scale score were compared with the clinical outcome.

  Result : Among the 47 hands (85%), 40 demonstrated a significantly improved grading scale score (Grade 1 to 4 after surgery), while the remaining (7 hands, 15%) did not (Grade 5 or 6 after surgery). The palmar CMAP/SNAP amplitudes of the non-improvement group had reduced considerably or had disappeared completely compared with those of the improvement group (p＜0.05, Wilcoxon rank-sum test), and the five-point rating scale was poorer in the non-improvement group than in the improvement group.

  Conclusion : In this study, the median palmar CMAP/SNAP amplitudes were associated with axonal degeneration, with the most important factors being related to an improvement in the grading scale score and prediction of the clinical outcomes.

  Objective : The three-dimensional magnetic resonance imaging (3D MRI) has facilitated image acquisition without slice gaps, with studies reporting its effectiveness in visualizing the lower cranial nerves. The 3D T2 sampling perfection with application-optimized contrast using different flip angle evolution (3D T2-SPACE) sequence is a 3D turbo spin-echo sequence that produces images with fewer cerebrospinal fluid flow artifacts and higher resolutions. In this study, we evaluated the visualization ability of the 3D T2-SPACE sequence in the cervical spine.

  Materials : We included 62 patients (39 men and 23 women ; mean age, 58 [14-85] years) who were admitted to our hospital with cervical spine lesions and were imaged with 2D T2-weighted image (T2WI) and 3D T2-SPACE sequences between April 2017 and March 2019. Data from 39 patients (23 men and 16 women ; mean age, 60 [17-80] years) were measured under identical conditions and with the same equipment to subsequently evaluate the contrast-to-noise ratio (CNR).

  Methods : We used the CNR in sagittal 2D T2WI and 3D T2-SPACE images to assess the visibility of anatomical structures by comparing the spinal cord, vertebral body, intervertebral disc, posterior longitudinal ligament, subcutaneous fat, and semispinalis cervicis muscle with the cerebrospinal fluid. We used the EU-proposed method for calculating CNR and paired t-tests for statistical analysis.

  Results : The 3D T2-SPACE sequence produced high-resolution multiplanar reconstruction images in considerably thin slices within 5-6 minutes. This sequence was particularly effective in examining cases of scoliosis and paraforaminal lesions, which is particularly challenging when using slice gaps in the 2D T2WI. Furthermore, the 3D T2-SPACE sequence showed fewer cerebrospinal fluid flow and magnetic susceptibility artifacts and a higher CNR than the 2D T2WI sequence (p＜0.01). The tissue contrast was significantly better in 3D T2-SPACE than in 2D T2WI images, which ensured excellent visibility.

  Conclusions : The 3D T2-SPACE sequence compensated for the disadvantages of the 3D gradient echo sequence. It generated a higher CNR than the 2D T2WI sequence. The 3D T2-SPACE sequence may have superior visibility over conventional methods and could be used as an alternative imaging method.

  An 85-year-old woman was admitted to our hospital for back pain and severe bilateral anterior thigh pain. She was radiographically diagnosed with an L2 osteoporotic vertebral compressed fracture accompanied by an intervertebral cleft with consequent bilateral L2/3 foraminal stenosis. We first performed a bilateral L2 root block since she had severe congestive heart failure. Her anterior thigh pain subsided thereafter, but she complained of left leg dominant paraparesis 8 weeks later. Magnetic resonance imaging (MRI) revealed a large cystic mass posterolaterally in the spinal canal, compressing the cauda equina at the T11-L1 level, with an intensity identical to that of fluid in the L2 vertebral cleft and cerebrospinal fluid (CSF). The wall of the cyst was enhanced by gadolinium-diethylenetriamine pentaacetic acid (GD-DTPA). Because of her severe paresis, the patient underwent T11-L1 left-side hemilaminectomy and removal of the cyst wall. The cyst wall was very thin and could not be dissected from the dura ; therefore, only the outer wall of the cyst was removed. The fluid in the cyst was serous and slightly yellowish. The resected cyst wall and fluid were culture-negative. Microscopic inspection showed granulation tissue mainly consisting of collagen fibers with bone and cartilage fragments. Although the patient showed marked recovery from paraparesis after the operation, the paraparesis deteriorated after extradural drain removal. MRI showed a recurrent large cystic mass and subcutaneous fluid collection. A computed tomography myelogram performed 6 hours after contrast medium (CM) injection showed relatively dense CM in the vicinity of the right L2 root and L2 vertebral cleft. However, CM in the cyst and subcutaneous space was thinner than that in the cleft. We speculated that the pseudoarthrosis of the L2 cleft drew CSF from the hole in the L2 root made by the root block into the L2 cleft with lumbar extension and excreted the pooled CSF into the extradural space with lumbar flexion. Histological findings suggested that the excreted CSF in the extradural space was converted to granulation tissue. Thereafter, the patient was treated successfully with spinal drainage and subsequent spinal column reconstruction surgery.

  Intraspinal cystic masses causing neurological deficits, which are considered to be derived from fluid in the intervertebral cleft, are extremely rare. To our knowledge, only three cases have been reported. We present a case with paraparesis caused by an intraspinal cystic mass derived from the intervertebral cleft in conjunction with an L2 root block.

  Primary central nervous system melanoma (PCNM) is a rare condition ; however, a PCNM localized to the spinal cord is even rarer. PCNM management is particularly controversial, with no clear guidelines.

  A 67-year-old man complained of bladder and rectal disturbance, paralysis, and dysesthesia of left leg. Spinal magnetic resonance imaging (MRI) revealed spinal cord tumors at the level of T12/L1 and T6/7. The intramedullary tumor at T12/L1 was partially resected and diagnosed as a malignant melanoma via histopathologic examination. Additionally, the brain lesions were identified through head MRI after surgery. Positron emission tomography/computed tomography revealed no lesions demonstrating malignant melanoma, excluding those in the brain and spine, which we diagnosed as PCNM. He was treated with nivolumab following radiotherapy for the PCNMs, leading to an improvement in his performance status from 3 to 1, without any apparent enlargements in the tumor. Seven months after the procedure, the patient presented with interstitial pneumonia as a side effect of nivolumab, following which we discontinued nivolumab. Head MRI at 13 months postoperatively revealed a regrowth of the brain lesion. We considered that nivolumab could potentially control its progress. Nivolumab treatment was resumed at 17 months with corticosteroid ; furthermore, we began administering ipilimumab at 21 months postoperatively, but the patient died at 2 years postoperatively.

  Here, we present a case showing the development of PCNM at the spinal cord, which was postoperatively treated with PD-1 inhibitor therapy.

  A retained medullary cord (RMC) is an infrequently reported closed spinal dysraphism caused by regression failure of the medullary cord during secondary neurulation. RMC is characterized by the lack of conus medullaris and filum terminale formation on magnetic resonance imaging (MRI) and under a microscope. The remaining robust elongated medullary cord often causes tethered cord syndrome. We herein report two cases of RMC―one of the stand-alone type and the other associated with terminal myelomeningocystocele―and discuss a definition of RMC based on embryology that is yet to be completely accepted. We also consider surgical procedures.

  Case 1 : A 4-year-old girl who presented with a lumbosacral subcutaneous mass at birth had continued enuresis until 4 years of age. MRI revealed a gradually shrinking spinal cord reaching the dural cul-de-sac without forming the conus medullaris and filum terminale. She underwent untethering surgery using the electromyographic procedure, and the function of the true conus medullaris and the true spinal nerves could be defined. The medullary cord and coccygeal nerves identified as non-functioning structures were resected. Her postoperative course was uneventful and the enuresis disappeared within 7 months after surgery.

  Case 2 : A 3-month-old girl showed a lumbosacral subcutaneous mass with a small dimple at birth. MRI indicated a robust elongated spinal cord without formation of the conus medullaris and filum terminale. Sacral meningocele and enlargement of the caudal central canal, namely the terminal myelomeningocystocele, were observed. She underwent repair of the terminal myelomeningocystocele and untethering, using the same electromyographic procedure as that used in case 1.

  It may be appropriate to define stand-alone RMC (as in case 1) as “narrow-sense RMC” and RMC associated with other anomalies (as in case 2) as “broad-sense RMC.” Otherwise, the definition of RMC should consist entirely of stand-alone RMC. Electrophysiological procedures are indispensable for defining the point of untethering.