Diffusion Tensor Imaging of the Median Nerve Before and After Carpal Tunnel Corticosteroid Injection in Patients With Carpal Tunnel Syndrome: Feasibility Study
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 12
- 主要终点
- Inter-scan change of DTI at baseline and 2 weeks after injection
研究概览
简要总结
Carpal tunnel syndrome (CTS) is the most common nerve compression disorder in the upper extremity. Therapy for carpal tunnel syndrome includes physical and occupational therapy, the use of splints and other local measures, and corticosteroid injection into the carpal tunnel. When these measures fail, open surgical release is considered the next step. Although the main disadvantage of corticosteroid injection is that symptoms are often short-lived relief and partial relief, it may not provide a permanent solution, corticosteroid injections are chosen because of lower level of invasiveness, faster recovery, and ease of the technique.
Diffusion tensor magnetic resonance imaging (DTI) reveals tissue microstructure based on random movements of water molecules. The measured diffusion-weighted images are further analyzed for parameter images that describe different characteristics of diffusion: apparent diffusion coefficient (ADC) is an absolute measure of the strength of diffusion, and fractional anisotropy (FA) describes the asymmetry of the diffusion direction due to tissue structures. Because the axonal cell membrane and the myelin sheath in nerve fibers prevent diffusion in the direction which is perpendicular to their fascicles, resulting in the isotropy of the diffusion of water molecules being lost. DTI is the only method which can give an indirect view of the microstructure of nervous tissue in addition to the pathway of the fibers.
DTI has been applied to study peripheral nerves, to demonstrate the feasibility of the method and to study nerve entrapment in carpal tunnel syndrome (CTS). The previous studies have demonstrated a decrease in FA in patients with CTS compared to healthy volunteers. The DTI parameters of the median nerve have revealed significant increase of FA and decrease in ADC with complete symptom relief 6 months after carpal tunnel release. However, Hiltunen et al. have demonstrated a significant decrease in ADC but no alter in FA in patients received open carpal tunnel release 1 year later and felt complete symptoms relief. By means of open carpal tunnel release, follow-up recordings were made at least 6 months after the operation to ensure time for post-operative tissue recovery. As a result, the investigators still do not understand the relevance between the parameters of DTI to symptoms relief in CTS patients receiving conservative treatment.
Different from carpal tunnel release, steroid injections are popular technique for CTS treatment and are believed to reduce perineural inflammation or soft tissue swelling, and may stabilize the neural membrane, thus limiting the ephaptic transmission in ischemic nerve fibers which causes symptoms. Corticosteroid injections can provide a rapid symptom relief at 2 weeks follow up. However, there is no report addressing the relation of functional change of median nerve at several anatomic locations to the symptom relief of CTS. Here the investigators monitored, by means of DTI, median nerve integrity in CTS patients before and after corticosteroid injection. This information may help to explain the hypothesis regarding the effect of corticosteroid to the median nerve, to identify which anatomic location of median nerve relevant to the symptom relief of CTS after corticosteroid injection, and be useful for the clinical follow-up of patients with nerve entrapments following conservative treatment.
详细描述
Study subjects This study was approved by the institutional research ethics board. Written informed consent was prospectively obtained from all study subjects. Twelve consecutive patients (nine females, three male; mean age, 56 years; range, 38 to 76 years) suffering from bilateral CTS referred for consideration of carpal tunnel steroid injection were prospectively recruited. Inclusion criteria consisted of a clinical diagnosis of unilateral or bilateral CTS based on a standardized and validated diagnostic scale. The degree of the entrapment ranged from mild to severe according to the American Association of Electrodiagnostic Medicine ratings: mild = slowing of sensory conduction velocity (<50 m/s), moderate = slowing of sensory conduction velocity (<50 m/s) and delayed motor distal latency (>4 ms), and severe = absence of sensory response. Exclusion criteria included prior carpal tunnel release or contraindications to MRI. All patients also had the clinical diagnosis supported by electrodiagnostic investigations.
Ultrasound needle guidance:
The US-guided injection procedure was performed in a standardized manner. The one-needle two-syringe technique with US guidance was used (1) one needle is used for anesthesia, hydrodissection, and intra-carpal tunnel injection; (2) the first syringe is used to anesthetize, hydrodissect, and dilate the intra-carpal tunnel space; and (3) the second syringe is used to inject the corticosteroid therapy into the new hydrodissected space. After hydrodissection, the empty lidocaine syringe was detached from the needle while still in the carpal tunnel, and a 3-ml syringe prefilled with 10 mg triamcinolone acetonide suspension was attached to the indwelling needle, and the treatment was slowly injected into the hydrodissected neutral space. The injections were performed in a standardized fashion by a musculoskeletal radiologist (Y.C.H.) with 13 years of experience in US.
MRI protocol Magnetic resonance images were acquired at 3.0 T (Discovery MR750, GE Healthcare, Milwaukee, WI, USA) using a 8-channel wrist coil (GE Healthcare, Gainesville, FL, USA). The coil was at the center of the magnet to maximize the magnetic-field homogeneity. The subject's hand was fixed with a plastic plate and Velcro tape to the coil to restrict movements; the subjects were examined in prone position.
For DTI, the investigators recorded non-diffusion-weighted b0 image and 15 diffusion gradient directions with b = 1,200 s/mm2 from 20 axial slices of 4 mm thickness. Slices were positioned to cover the whole carpal tunnel and in part the proximal and distal nerve. The two most proximal and distal slices were excluded from the analysis because of potential bias caused by the rapid decrease in homogeneity at the edge of the coil. Thus, the total proximal-distal range examined was 80 mm. The other imaging parameters were as follows: repetition time (TR) = 10,000 ms, echo time (TE) = 101 ms, number of averages = 3 (during post-processing), field of view (FOV) = 12 cm and matrix 100 × 80 pixels. The voxel size was thus 1.46 × 1.46 ×4 mm3.
研究设计
- 研究类型
- Observational
- 观察模型
- Case Only
- 时间视角
- Prospective
入排标准
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •clinical diagnosis of unilateral or bilateral CTS based on a standardized and validated diagnostic scale
排除标准
- •prior carpal tunnel release or contraindications to MRI
结局指标
主要结局
Inter-scan change of DTI at baseline and 2 weeks after injection
时间窗: February, 2017
The DTI values for each wrist at baseline were compared to the DTI of the same wrist at 2 weeks in individual patients. DTI parameters: FA (numeric; unit free), ADC (numeric; unit: mm2/s), and DTT (morphology, unit free); BCTQ (numeric; unit free)
Correlation of Inter-scan change of DTI with symptoms relief
时间窗: February, 2017
The investigators determined the inter-scan correlation between increment of DTI parameters and the decrement of BCTQ. DTI parameters: FA (numeric; unit free), ADC (numeric; unit: mm2/s), and DTT (morphology, unit free); BCTQ (numeric; unit free)
次要结局
未报告次要终点
研究者
yi-chih HSU
Radiologist
Tri-Service General Hospital