High-resolution MRI predicts steroid injection response in carpal tunnel syndrome patients

Prediction of carpal tunnel syndrome using the thenar muscle cross-sectional area by magnetic resonance imaging

Carpal tunnel syndrome (CTS) is a common neuropathy. Although CTS progression is known to be associated with thenar muscle (TM) atrophy, the diagnostic value of TM atrophy for CTS has not been established. In this research, the thenar muscle cross-sectional area (TMCSA) was evaluated to analyze the relationship between the TMCSA and CTS. We assumed that TMCSA is a major diagnostic parameter in the CTS.Both TMCSA and thenar muscle thickness (TMT) samples were acquired from 18 CTS patients, and from 18 control subjects who underwent wrist magnetic resonance imaging with no evidence of CTS. T2-weighted transverse magnetic resonance imaging images were obtained. We measured the TMCSA and TMT at the level of first carpometacarpal joint.The average TMCSA was 296.98 ± 49.39 mm2 in the normal group and 203.36 ± 72.13 mm2 in the CTS group. The average TMT was 8.54 ± 1.45 mm in the normal group and 7.38 ± 1.14 mm in the CTS group. CTS group had significantly lower TMCSA and TMT. Receiver operator characteristics curve analysis showed that the best cutoff point for the TMCSA was 260.18 mm2, with 77.8% sensitivity, 77.8% specificity. The best cutoff point of the TMT was 7.70 mm, with 61.1% sensitivity, 66.7% specificity.Although the TMCSA and TMT were both significantly associated with CTS, the TMCSA was a much more sensitive measurement parameter. Thus, to evaluate CTS patients, the physician should more carefully inspect the TMCSA than TMT.

Molecular and Clinical Elucidation of the Mechanism of Action of Steroids in Idiopathic Carpal Tunnel Syndrome

BACKGROUND

Carpal tunnel steroid injection is a nonoperative intervention for the treatment for idiopathic carpal tunnel syndrome (CTS). The antifibrotic, anti-inflammatory, and antiedematous properties of steroids account for their therapeutic effects in the context of CTS; however, their relative contribution has not been clarified.

METHODS

Fibroblasts from subsynovial connective tissues (SSCT) were intraoperatively collected from patients with idiopathic CTS and were incubated with or without the steroid triamcinolone acetonide (TA) for 1, 3, and 7 days; the expression of fibrosis-related genes and inflammatory cytokines was evaluated using quantitative reverse transcription-polymerase chain reaction. A clinical prospective study was conducted with patients who received carpal tunnel TA injections. We performed clinical and electrophysiological evaluations before and 1, 3, and 5 months after TA injection; and we compared the median nerve, flexor tendon, and SSCT areas and the median nerve flattening ratio before and 1 month after TA injection using 3-T magnetic resonance imaging (MRI).

RESULTS

TA induced downregulation of the fibrosis-related genes Col1A1 (collagen type I alpha 1 chain), Col1A2, and Col3A1 but not the inflammation-related genes. The nerve flattening ratio did not change after TA injection according to the MRI-based observation of the median nerve, flexor tendon, and SSCT areas.

CONCLUSIONS

The therapeutic effects of injected TA are apparently mediated by its antifibrotic rather than its anti-inflammatory and antiedematous properties. TA probably alters the properties but not the morphology of SSCT.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Amyloidosis: Multisystem Spectrum of Disease with Pathologic Correlation

Amyloidosis is a group of conditions defined by extracellular deposition of insoluble proteins that can lead to multiorgan dysfunction and failure. The systemic form of the disease is often associated with a plasma cell dyscrasia but may also occur in the setting of chronic inflammation, long-term dialysis, malignancy, or multiple hereditary conditions. Localized forms of the disease most often involve the skin, tracheobronchial tree, and urinary tract and typically require tissue sampling for diagnosis, as they may mimic many conditions including malignancy at imaging alone. Advancements in MRI and nuclear medicine have provided greater specificity for the diagnosis of amyloidosis involving the central nervous system and heart, potentially obviating the need for biopsy of the affected organ in certain circumstances. Specifically, a combination of characteristic findings at noninvasive cardiac MRI and skeletal scintigraphy in patients without an underlying plasma cell dyscrasia is diagnostic for cardiac transthyretin amyloidosis. Histologically, the presence of amyloid is denoted by staining with Congo red and a characteristic apple green birefringence under polarized light microscopy. The imaging features of amyloid vary across each organ system but share some common patterns, such as soft-tissue infiltration and calcification, that may suggest the diagnosis in the appropriate clinical context. The availability of novel therapeutics that target amyloid protein fibrils such as transthyretin highlights the importance of early diagnosis. Online supplemental material is available for this article. ^©RSNA, 2021.

[Acute carpal tunnel syndrome regarding clinico-anatomical point of view in personified medicine]

Carpal tunnel syndrome (CTS) requires special attention due to its different reasons and course. Knowledge about the variability of median nerve (MN) topography in carpal canal region, features of diagnosis and treatment extends outlooks on this pathology. Aggregating rare clinical cases from the Medline and Pubmed databases is useful to form personified approach. There are 3 types of topographic variations which should be considered to prevent false-positive diagnosis of pathology: recurrent branch location, early bi- and trifurcations of MN, anastomoses. Since acute CTS is treated only by surgery, every surgical approach is aimed at minimally invasiveness and fast recovery. Endoscopic decompression (ED) is more favorable regarding these aspects. However, this method cannot be considered as perfect due to available data about incomplete decompression and certain incidence of recurrences. The last ones are absent after microsurgical decompression as a rule. It can be concluded that only individual approach is advisable for complete release of CTS without iatrogenic damage and recurrences.

Diffusion-weighted magnetic resonance neurography for the diagnosis of carpal tunnel syndrome: a pilot study

AIM

To investigate the applicability of diffusion-weighted magnetic resonance neurography (DW-MRN) in the diagnosis of carpal tunnel syndrome (CTS).

MATERIALS AND METHODS

In total, 47 patients with CTS (69 wrists) and 19 normal participants (38 wrists) was included in this study. Cross-sectional area (CSA) and apparent diffusion coefficient (ADC) values of the median nerves in the carpal tunnel were determined using DW-MRN. Receiver operating characteristic (ROC) analysis was performed.

RESULTS

No significant differences in age or body mass index (BMI) were observed between the control and CTS groups. DW-MRN imaging showed obvious hyperintensity in the lesions in CTS wrists, while other nerve regions were related to slight hyperintensity. Interobserver variability analysis indicated excellent agreement regarding both the CSA and ADC measurements for the control and CTS groups. Both the mean CSA and ADC values of the median nerves in carpal tunnel in the CTS group were significantly higher than the control group. According to the ROC analysis, the CSA cut-off value was 11.7 mm², and sensitivity and specificity were 66.7% and 89.5%, respectively. Conversely, the median nerve ADC cut-off value was 1.047×10^-3 mm²/s. The sensitivity and specificity were 91.3% and 76.3.9%, respectively.

CONCLUSION

DW-MRN represents a highly reproducible diagnostic technique for CTS. The ADC value of median nerves in the carpal tunnel is significantly higher in CTS patients, which provides a potential powerful tool for the disease diagnosis.

Peripheral nerve imaging

Disorders of peripheral nerve have been traditionally diagnosed and monitored using clinical and electrodiagnostic approaches. The last two decades have seen rapid development of both magnetic resonance imaging (MRI) and ultrasound imaging of peripheral nerve, such that these imaging modalities are increasingly invaluable to the diagnosis of patients with peripheral nerve disorders. Peripheral nerve imaging provides information which is supplementary to clinical and electrodiagnostic diagnosis. Both MRI and ultrasound have particular benefits in specific clinical circumstances and can be considered as complementary techniques. These technologic developments in peripheral nerve imaging will usher in an era of multimodality assessment of peripheral nerve disorders, with clinical evaluations supported by anatomic information from imaging, and functional information from electrodiagnostic studies. Such a multimodality approach will improve the accuracy and efficiency of patient care.