T2 magnetic resonance imaging mapping and morphology of the median nerve before and after surgery in carpal tunnel syndrome.

INTRODUCTION/AIMS: T2 magnetic resonance imaging (MRI) mapping has been applied to carpal tunnel syndrome (CTS) for quantitative assessment of the median nerve. However, quantitative changes in the median nerve before and after surgery using T2 MRI mapping remain unclear. We aimed to investigate whether pathological changes could be identified by pre- and postoperative T2 MRI mapping of the median nerve in CTS patients after open carpal tunnel release. METHODS: This was a prospective study that measured median nerve T2 and cross-sectional area (CSA) values at the distal carpal tunnel, hamate bone, proximal carpal tunnel, and forearm levels pre- and postoperatively. Associations between T2, CSA, and nerve conduction latency were also evaluated. RESULTS: A total of 36 patients with CTS (mean age, 64.5 ± 11.7 years) who underwent surgery were studied. The mean preoperative T2 values significantly decreased from 56.3 to 46.9 ms at the proximal carpal tunnel levels (p = .001), and from 52.4 to 48.7 ms at the hamate levels postoperatively (p = .04). Although there was a moderate association between preoperative T2 values at the distal carpal tunnel levels and distal motor latency values (r = -.46), other T2 values at all four carpal tunnel levels were not significantly associated with CSA or nerve conduction latency pre- or postoperatively. DISCUSSION: T2 MRI mapping of the carpal tunnel suggested a decrease in nerve edema after surgery. T2 MRI mapping provides quantitative information on the median nerve before and after surgery.

Comparative study on the effectiveness of bone grafting for arthrodesis of the thumb carpometacarpal arthritis.

The aim of this retrospective study was to assess the effectiveness of autogenous bone grafting for arthrodesis of the thumb carpometacarpal joint by comparing the bone union rates with and without bone grafting. We included 36 patients who underwent arthrodesis of the thumb carpometacarpal joint for arthritis (20 patients with bone grafts and 16 without bone grafts). Implants used for internal fixation were K-wire, tension band wiring, headless compression screw and locking plate. The presence of bone union and the time from surgery to bone union were evaluated. The bone union rate was 20/20 (100%) in the bone grafting group and 12/16 (75%) in the non-bone grafting group (p = 0.03). There were no significant differences between the two groups in the time from surgery to bone union and patient characteristics. In conclusion, autogenous bone grafting may contribute to the bone union in the arthrodesis of thumb carpometacarpal arthritis.Level of evidence: III.

Repeated magnetic resonance imaging at 6 follow-up visits over a 2-year period after platelet-rich plasma injection in patients with lateral epicondylitis.

BACKGROUND: The efficacy of platelet-rich plasma (PRP) for lateral epicondylitis has been demonstrated. However, the healing process monitored by repeated magnetic resonance imaging (MRI) is unclear. The purpose of this study was to evaluate sequential changes using MRI in patients with lateral epicondylitis treated by PRP injection at 6 follow-up visits over a 2-year period. METHODS: Thirty patients who underwent PRP treatment for lateral epicondylitis and sequential MRI evaluation were prospectively enrolled. The MRI scores (ranging from 0 to 3) and clinical scores, including the visual analog scale (VAS) pain score and Patient-Rated Tennis Elbow Evaluation (PRTEE) score, were measured at baseline (before treatment) and 1, 3, 6, 12, 18, and 24 months after the procedure. Sequential changes in the MRI scores and clinical scores during the treatment period were evaluated. In addition, the associations between MRI scores and clinical scores were assessed. RESULTS: The mean MRI score at baseline was 2.30, and the mean MRI scores at 1, 3, 6, 12, 18, and 24 months after the procedure were 1.97, 1.77, 1.13, 0.73, 0.60, and 0.33, respectively. Significant improvements in the MRI scores occurred by 3 months and continued over a period of 24 months. Regarding the clinical scores, the mean VAS pain scores were 72 at baseline, 48 at 1 month, 34 at 3 months, 28 at 6 months, 15 at 12 months, 14 at 18 months, and 11 at 24 months and the mean PRTEE scores were 56, 36, 26, 18, 8, 9, and 6, respectively. Significant improvements in the VAS pain score and PRTEE score occurred by 1 month and continued over a period of 12 months. There was little association between the MRI scores and clinical scores. CONCLUSIONS: Continuous tendon recovery assessed by MRI was found during a 2-year period after PRP treatment. Improvements in the MRI scores followed and continued longer than improvements assessed by the clinical scores.

Visualization of the morphological changes in the median nerve after carpal tunnel release using three-dimensional magnetic resonance imaging.

OBJECTIVES: This study aimed to compare the pre- and postoperative morphology of the median nerve using three-dimensional (3-D) MRI in patients with carpal tunnel syndrome (CTS). METHODS: We assessed 31 patients with CTS who underwent open carpal tunnel release and T2*-weighted MRI of the wrist preoperatively and at 6 months postoperatively. The median nerve morphology was evaluated on the basis of the cross-sectional areas (CSAs) and cross-sectional volumes (CSVs). The association between these MRI findings and nerve conduction studies was also evaluated. RESULTS: The mean preoperative CSA and CSV values at the proximal carpal tunnel level significantly decreased from 22.2 mm2 and 24.4 mm3 to 16.5 mm2 and 18.1 mm3, respectively, postoperatively. Median nerve swelling at the proximal carpal tunnel level was observed in 29 (94%) and 23 (74%) patients before and after surgery, respectively. The mean preoperative CSA and CSV values at the hamate level significantly increased from 9.9 to 12.3 mm2 and from 10.9 to 13.5 mm3 after surgery, respectively. Nerve narrowing at the hamate bone level was preoperatively observed in 28 (90%) patients and postoperatively in 21 (68%) patients. Preoperative CSA and CSV values at the proximal carpal tunnel were significantly associated with preoperative distal motor and sensory latency. CONCLUSIONS: Visual confirmation of the median nerve morphology using 3-D MRI is useful when considering postoperative recovery and explaining the nerve condition to the patients. KEY POINTS: • The 3-D morphology of the median nerve after carpal tunnel release can be delineated using 3-D MRI. • Preoperative swelling of the median nerve in the 2-D and 3-D planes reflects the severity of carpal tunnel syndrome. • Visual confirmation of the median nerve morphology is useful when considering median nerve recovery after carpal tunnel release and for explaining the condition of the nerve to patients.

T2 mapping of the median nerve in patients with carpal tunnel syndrome and healthy volunteers.

INTRODUCTION: We investigated the changes in MRI T2 mapping values in subjects with carpal tunnel syndrome (CTS) compared to healthy controls. METHODS: We enrolled 71 patients with CTS and 26 healthy controls. Median nerve T2 values were measured at the distal carpal tunnel, hamate bone, proximal carpal tunnel, and forearm levels. These were compared between patients and controls and correlated with median nerve cross-sectional area (CSA) and nerve conduction measurements. RESULTS: The mean T2 values at the proximal carpal tunnel levels were higher in the CTS group (56.7 ms) than in the control group (51.2 ms, P = .02) and also were higher than at the distal carpal tunnel (51.0 ms, P < .001) and forearm levels (47.6 ms, P < .001). T2 values were not significantly associated with CSA or nerve conduction measurements. DISCUSSION: T2 mapping of the carpal tunnel provides qualitative information on median nerve pathology but does not reflect CTS severity.

Motion of the distal radioulnar joint in extension and flexion of the wrist using axial CT imaging of healthy volunteers.

BACKGROUND: The midcarpal joint and the radiocarpal joint contribute to the extension and flexion of the wrist. Little is known about the contribution of the distal radioulnar joint (DRUJ) to the extension and flexion of the wrist. This study evaluated the ulnar motion in extension and flexion of the wrist using computed tomography (CT) imaging. METHODS: A total of 30 wrists of healthy volunteers were enrolled. CT images of the axial sections of the DRUJ were obtained with 3 different positions of the wrist: 0° of extension (straight position), maximum active extension, and maximum active flexion. Each wrist motion was performed with 3 different forearm positions: neutral, pronation, and supination. Ulnar position at the DRUJ level was measured and ulnar position with the wrist in straight position was defined as baseline. The ulnar position was recorded as positive value when the position of the ulnar head was volar side and negative value when the position of the ulnar head was dorsal side. The difference from baseline in a position of maximum extension and flexion was evaluated. RESULTS: In forearm neutral position and pronation, a value of ulnar position in maximum wrist flexion is significantly negative compared to that in the wrist straight position: the ulnar head moved dorsally from the wrist straight position to wrist flexion. In forearm supination, a value of ulnar position in maximum wrist extension is significantly positive compared to that in the wrist straight position: the ulnar head moved to the volar side from the wrist straight position to wrist extension. CONCLUSIONS: The ulnar head moves during extension and flexion of the wrist. The direction of the ulnar motion was different according to the wrist and forearm position.

Sauvé-Kapandji procedure with headless compression screw in patients with rheumatoid arthritis.

OBJECTIVE: We examined the surgical outcomes of the Sauvé-Kapandji (S-K) procedure using a headless compression screw and a metal cancellous screw in patients with rheumatoid arthritis (RA). METHODS: This retrospective study included 41 RA patients who underwent the S-K procedure for distal radioulnar joint disorders with two screws: headless compression screws (HCS group, n = 20) and cannulated cancellous screws (CCS group, n = 21). Clinical and radiographic outcomes were assessed 1 year after surgery. Radiographic outcomes included bony union of the distal radioulnar joint (DRUJ), bone resorption around the screw, a screw back-out, and use of additional K-wire. We investigated any complications related to the screw head. RESULTS: All 20 patients in the HCS group showed bone fusion of the DRUJ. In the CCS group, an asymptomatic non-union was observed in one patient and additional K-wire was needed to stabilize the DRUJ in three patients. No patients complained of any complications related to the screw head in the HCS group, while the CCS group demonstrated the hardware protrusion in two patients who complained of tenderness or discomfort at the screw head. CONCLUSIONS: The use of a headless compression screw in the S-K procedure is useful in patients with RA.

Circulatory dynamics of the cauda equina in lumbar canal stenosis using dynamic contrast-enhanced magnetic resonance imaging.

BACKGROUND CONTEXT: There has been no study regarding the cauda equina circulation of patients with neurogenic intermittent claudication (NIC) in lumbar spinal canal stenosis (LSCS) using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). PURPOSE: The mechanism responsible for the onset of NIC was investigated using DCE-MRI to examine changes in cauda equina blood flow in patients with LSCS. STUDY DESIGN: This was a retrospective longitudinal registry and magnetic resonance imaging study. PATIENT SAMPLE: The subjects consisted of 23 patients who had LSCS associated with NIC (stenosis group). Ten asymptomatic volunteers who did not have NIC served as controls (control group). In the LSCS group, the cross-sectional area of the dural sac was <75 mm2 at the site of most severe stenosis. These patients were further divided into single and double stenosis subgroups. OUTCOME MEASURES: The main measures we used were the signal intensity (S-I) ratio and the shape and size of the time intensity (T-I) curves. We compared these between the stenosis and control groups. METHODS: At first, plain T1-weighted MR images were obtained and the lumbar dural sac cross-sectional area was measured using a digitizer. For DCE-MRI, sagittal T1-weighted images of the same slice were acquired continuously for 10 minutes after administration of gadolinium as an intravenous bolus to observe the distribution of contrast medium (gadolinium) in the cauda equina. To objectively evaluate changes in contrast enhancement of the cauda equina at the site of canal stenosis, regions of interest were established. The signal intensity (SI) ratio was calculated to compare the signal intensities before and after contrast enhancement, and time-intensity curves were prepared to investigate changes over time. RESULTS: The static imaging findings and the changes of gadolinium uptake showed striking differences between the study and control patients. In the stenosis group, abnormal intrathecal enhancement showed around the site of stenosis on enhanced MR imaging. The SI ratio at the site of canal stenosis had a slower increase in the arterial phase when compared with that in the control group and remained high in the venous phase for up to 10 minutes. Finally, abnormal intrathecal enhancement was visible around the site of stenosis on enhanced MR imaging in all patients. CONCLUSIONS: These clinical data indicate that cauda equina nerve roots in the LSCS patients are pathologic even when symptoms are not elicited in the supine position, suggesting that intraradicular venous congestion and edema themselves do not influence the existence of radicular symptoms.

Visualization of intraneural edema using gadolinium-enhanced magnetic resonance imaging of carpal tunnel syndrome.

BACKGROUND: In general, carpal tunnel syndrome (CTS) is diagnosed based mainly on clinical findings and electrophysiology. However, the pathological state of the compressed median nerve could not be shown on imaging. Gadolinium-enhanced magnetic resonance (MR) imaging may give us an idea about the status of the blood-nerve barrier of peripheral nerves. Therefore, detecting intraneural edema may be a way of diagnosing entrapment neuropathy. The present study investigated the diagnostic role of gadolinium-enhanced MR imaging of CTS. METHODS: The subjects were 23 patients (34 hands) with idiopathic CTS. To serve as control subjects, 12 wrists of asymptomatic volunteers were studied. Using the spin-echo method, T1- and T2-weighted axial MR images were obtained. Intravenously injected gadolinium was used to obtain enhanced images. We studied the relation between nerve enhancement and the symptomatology. RESULTS: After intravenous injection of gadolinium, there was no enhancement of the unaffected nerves in the carpal tunnels of the control group. Gadolinium enhancement was found in only 87% of patients with CTS who visited the hospital at an early stage and therefore had no nerve deficiency on electrophysiological studies (39%). Based on this finding, during the early stages when the nerve is in a state of neuropraxia, gadolinium-enhanced MR imaging of the median nerve might prove to be the most sensitive modality for detecting early nerve dysfunction. MR imaging also revealed a higher frequency of enhancement in the advanced stage of CTS with muscle atrophy. CONCLUSIONS: We conclude that gadolinium-enhanced MR imaging can detect not only morphological changes but also pathological changes of the median nerve in patients with CTS. Currently, gadolinium-enhanced-MR imaging is probably most commonly used to image patients who have ambiguous electrodiagnostic studies and clinical examination in an early stage of CTS.

A case of nerve root heat injury induced by percutaneous laser disc decompression performed at an outside institution: technical case report.

OBJECTIVE: In recent years, percutaneous laser disc decompression (PLDD) has become a routine surgical procedure because it can be performed under local anesthesia and is minimally invasive. However, there is a risk of nerve root and endplate injury owing to heat generated by laser irradiation during PLDD. We recently performed salvage surgery on a patient with heat injury to the L5 nerve root that developed after PLDD. CLINICAL PRESENTATION: One month before presenting to our hospital, the patient underwent two sessions of PLDD for lumbar vertebral disk herniation at another institution. The patient developed worsening sciatica, as well as bowel and urinary problems after the PLDD. INTERVENTION: We performed salvage surgery after PLDD. The intraoperative findings in the present case included carbon spots in the dura mater of the nerve root and a disc herniation strongly adherent to the nerve roots. These findings indicate that the area adjacent to the nerve roots was damaged by excessive heat during laser irradiation. CONCLUSION: When salvage surgery is performed after a PLDD procedure, disc and nerve root injuries owing to laser heat energy must be considered.

Salvage operation for persistent low back pain and sciatica induced by percutaneous laser disc decompression performed at outside institution: correlation of magnetic resonance imaging and intraoperative and pathological findings.

OBJECTIVE: We identified several problems associated with percutaneous lumbar disc decompression (PLDD) based on a study of patients who required salvage operations for complications after undergoing PLDD at an outside institution. BACKGROUND DATA: PLDD has been performed as a new treatment for intervertebral disc herniation in recent years, and its safety and effectiveness are in the process of being established. Because the procedure is simple to perform under local anesthesia, inappropriate irradiation and application to patients for whom it is not indicated have sometimes resulted in a poor outcome and serious complications. METHODS: The patients comprised 10 with lumbar disc herniation and three with lumbar spondylolisthesis. We analyzed the magnetic resonance (MR) imaging and operative findings as well as the pathological features of surgically obtained disc specimens and studied their relationships with the clinical outcomes of the operations. RESULTS: Initial examination of all patients at our hospital showed that PLDD had no effect on low back pain or sciatica. In patients who showed MR signal changes in the end-plate, the pathological examination revealed extensive necrosis of cartilage and bone. During salvage operations, severe adhesion of herniated masses to nerve roots was often observed, with carbonized disc tissue surrounding the nerve roots and might have their nerve root injured thermally. CONCLUSION: PLDD is associated with significant risk of disc, end-plate, and nerve root injuries, contrary to the general belief that the procedure is minimally invasive. Our findings highlight the need for careful diagnosis and sufficient technical skill when selecting PLDD as a treatment option.

Imaging of intraneural edema by using gadolinium-enhanced MR imaging: experimental compression injury.

BACKGROUND AND PURPOSE: Compressive and entrapment neuropathies are diseases frequently observed on routine clinical examination. A definitive diagnosis based on clinical symptoms and neurologic findings alone is difficult in many cases, however, and electrophysiologic measurement is used as a supplementary diagnostic method. In this study, we examined to use protein tracers (Evans blue albumin or horseradish peroxidase) and gadolinium-enhanced MR imaging to determine the changes of blood-nerve barrier permeability in compressive neuropathies. METHODS: In dogs, the median nerve was compressed for 1 hour by using five kinds of clips with various strengths (7.5-90-g force). After clip removal, the combined tracers of Evans blue albumin and gadolinium or horseradish peroxidase was administered intravenously as a tracer. After the animals were euthenized, we compared gadolinium-enhanced MR images with Evans blue albumin distribution in the nerve under fluorescence microscopy. The horseradish peroxidase-injected specimens were observed by transmission electron microscopy. RESULTS: On enhanced MR imaging, intraneural enhancement was caused by 60- and 90-g-force compression after 1 hour. Marked extravasation of protein tracers in the nerve occurred where there was compression by 60- and 90-g-force compression, and capillaries in the nerve showed the opening of tight junction and an increase of vesicular transport under the electron microscopy. This situation indicated breakdown of the blood-nerve barrier, with consequent edema formation and was seen as enhancement on MR imaging. CONCLUSION: Gadolinium-enhanced MR imaging can detect morphologic and functional changes of blood-nerve barrier in the nerve induced by mechanical compression.