Toshiro Itsubo

Quantitative MRI of the wrist and nerve conduction studies in patients with idiopathic carpal tunnel syndrome

Objective: To correlate morphological findings of idiopathic carpal tunnel syndrome (CTS) with the function of the median nerve. Methods: In this study, 105 wrists of 105 women patients with idiopathic CTS, and 36 wrists of 36 female volunteers were subjected to nerve conduction studies and MRI. Cross sectional area, signal intensity ratio, and the flattening ratio of the median nerve, carpal tunnel area, flexor tendon area, synovial area, and intersynovial space, and the palmar bowing of the transverse carpal ligament (TCL) were quantified by MRI and correlated with the severity of the disease determined by nerve conduction studies. Results: Cross sectional areas of the median nerve, flexor tendons, and carpal tunnel, and the palmar bowing of the TCL of the CTS groups were greater than in the control group, but differences were not detected among the CTS groups for the area of the flexor tendons and the carpal tunnel. Enlargement, flattening, and high signal intensity of the median nerve at the distal radioulnar joint level were more significant in the advanced than in the earlier stages of the disease. Increase in palmar bowing of the TCL was less prominent in the most advanced group. Linear correlation between the area of the carpal tunnel and palmar bowing of the TCL was noted. Conclusion: Severity of the disease could be judged by evaluating not only longitudinal changes of signal intensity and configuration of the median nerve, but also palmar bowing of the TCL. Increased palmar bowing of the TCL was found to be associated with an increase in the area of the carpal tunnel.

Microendoscopic discectomy (MED) for lumbar disc prolapse

Microendoscopic discectomy (MED), which combines traditional lumbar microsurgical techniques with endoscopy, is being used as a minimally invasive procedure for lumbar disc herniation. We reviewed 30 patients who underwent MED at our institution and compared their outcome with that of patients subjected to the conventional method. Laboratory data suggested that MED was less invasive surgery. Moreover, MED allowed an early return to work. However, the difficulties of this endoscopic procedure were evident, because of the limited exposure and two-dimensional video display. The potential injury of the nerve root and prolonged surgical time remain as matters of serious concern. To overcome this problem, we used an operative magnifying glass during surgery and this helped us to accomplish the procedure comfortably. We recommend the use of an operative magnifying glass in the early stage of the introduction of MED, for it is quite useful to identify the three-dimensional relationships of the structures.

Magnetic Resonance Imaging Staging to Evaluate the Stability of Capitellar Osteochondritis Dissecans Lesions

Background: Treatment for capitellar osteochondritis dissecans (COCD) lesions is usually based on their stability from the bony floor after arthroscopic or open direct observation. Thus, a noninvasive means of lesion stability assessment by use of imaging is desirable to preoperatively determine treatment strategy. Purpose: To evaluate our modified MRI staging system for COCD, we compared the results of MRI staging with the International Cartilage Repair Society (ICRS) classification for lesion stability. Intra- and interrater reliability for MRI staging was examined as well. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Fifty-two COCD lesions were preoperatively evaluated by T2-weighted MRI and classified into 5 stages: stage 1 = normally shaped capitellum with several spotted areas of high signal intensity that is lower than that of cartilage; stage 2 = as with stage 1 but with several spotted areas of higher intensity than that of cartilage; stage 3 = as with stage 2 but with both discontinuity and noncircularity of the chondral surface signal of the capitellum and no high signal interface apparent between the lesion and the floor; stage 4 = lesion separated by a high intensity line in comparison with cartilage; and stage 5 = capitellar lesion displaced from the floor or defect of the capitellar lesion noted. The MRI staging results were compared with the intraoperative ICRS classification for lesion stability of each patient. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were all determined for fragment instability. Intra- and interrater correlations for our MRI staging were calculated among 3 examiners. Results: Preoperative MRI grading correctly matched ICRS classification in 49 of 52 patients (94%), with a sensitivity of 100% and a specificity of 80%. The PPV and NPV were 93% and 100%, respectively, for diagnosing lesion instability. Intrarater reliability (intraclass correlation coefficient [ICC]) for MRI staging was high at ICC(1, 1) = 0.86 and ICC(1, 2) = 0.90, as was interrater reliability at ICC(2, 1) = 0.82 and ICC(2, 3) = 0.88. Conclusion: The MRI staging system provides accurate and reliable evidence for estimating ICRS classification and instability of COCD and is useful to decide appropriate treatment.

Electrophysiological responsiveness and quality of life (QuickDASH, CTSI) evaluation of surgically treated carpal tunnel syndrome.

BackgroundWe evaluated the correlation between Japanese versions of patient-oriented questionnaires and electrophysiological examinations in patients with carpal tunnel syndrome (CTS).MethodsA series of 45 patients who were diagnosed with carpal tunnel syndrome and subsequently underwent carpal tunnel release surgery were analyzed. There were 8 men and 37 women with an average age of 64.8 years. They completed the Japanese Society for Surgery of the Hand version of the Carpal Tunnel Syndrome Instrument (CTSI-JSSH), which consisted of a Symptom Severity Score (CTSI-JSSH-SS), Functional Score (CTSI-JSSH-FS), and Japanese Society for Surgery of the Hand version-Quick Disability of Arm, Shoulder, and Hand questionnaire (QuickDASH-JSSH) both preoperatively and 3 months postoperatively. Nerve conduction studies (NCSs) were also performed and included motor distal latency (MDL) and sensory nerve conduction velocity (SCV) measurements. The responsiveness of each instrument was evaluated by calculating the standardized response mean (SRM) and effect size (ES). Correlation coefficients between preoperative and postoperative questionnaire scores and NCS parameters were calculated.ResultsResponsiveness (SRM/ES) was as follows: CTSI-JSSH-SS (-1.06/-1.14), CTSI-JSSH-FS (-0.75/-0.74), Quick-DASH-JSSH (-0.65/-0.62), MDL (-1.45/-1.11), and the neurophysiological stage of the disease (-0.90/-1.42). No significant correlation was observed between the preoperative and postoperative patient-oriented questionnaires and nerve conduction studies (P > 0.05).ConclusionsAlthough NCSs and the Japanese version of patient-oriented questionnaires are highly responsive to treatment, they are not parallel. Multifaceted assessment of CTS treatment is possible by performing both outcome measurements.

Idiopathic spinal cord herniation associated with a large erosive bone defect: a case report and review of the literature.

We report a case of idiopathic spinal cord herniation associated with a large bone defect. MRI and computed tomographic myelography revealed ventral deviation of the spinal cord and erosion of the vertebral body at T6–T7. Microscopic surgery revealed a dural defect. The etiology of this condition has not been clarified. In most previously reported cases, the peak portion of the herniation was around the intervertebral disc space. In addition, in our patient, it was hard to think that the intervertebral disc has become depressed due to the pressure exerted by the spinal cord. We considered that a certain condition of the intervertebral disc, such as herniation, was one of the causes of the dural defect, and cerebrospinal fluid pulsation pushed the spinal cord toward that portion, causing herniation.

Differential onset patterns and causes of carpal tunnel syndrome after distal radius fracture: a retrospective study of 105 wrists

BackgroundIt is well known that carpal tunnel syndrome (CTS) can occur in a wide range of time periods after distal radius fracture (DRF). Few studies have evaluated in detail the relationship between fracture and electrophysiological finding characteristics and time to onset of CTS after DRF. To clarify the characteristics of CTS after DRF, we classified a large number of clinical cases based on the period from the injury to onset of CTS. These cases were analyzed retrospectively.MethodsWe reviewed 105 wrists with CTS following DRF. Patients’ ages ranged from 13 to 89 years. These 105 wrists were divided into three groups according to the period of post-fracture onset of CTS. Twenty-eight wrists were classified into the acute onset group (when the symptoms of CTS occurred within 1 week after fracture). Forty-seven wrists were classified into the subacute onset group (when symptoms of CTS occurred from 1 to 12 weeks after fracture). The remaining 30 wrists were classified into the delayed onset group (when symptoms of CTS occurred more than 12 weeks after fracture). Deformity of the distal radius on X-ray films was evaluated and distal motor latency (DML) of the median nerve was recorded to compare values among these three groups.ResultsIn the acute onset group, 68% had an AO C-type fracture and 46% were caused by a high-energy injury. The percentage of this fracture pattern and mechanism was significantly higher in the acute onset group than in the other groups (P < 0.05; Kruskal-Wallis test). In the subacute onset and delayed onset groups, 79% and 63% had an A-type fracture and more than 90% were caused by a low-energy injury. In the delayed onset group, the incidence of prolonged DML in the contralateral wrists was 71%, which was significantly higher than in the other two onset groups (P < 0.05; Kruskal- Wallis test).ConclusionsThere were three onset patterns of CTS after DRF, and each CTS onset pattern had different etiologic mechanisms and different clinical features of CTS. In the acute onset group, a high-energy fracture pattern was associated with CTS. In the subacute and the delayed onset groups, lowenergy injury in elderly women was associated with CTS. Both deformity of the fracture and preexisting median nerve dysfunction were suggested as predisposing factor for CTS.

Technical Difficulties and Their Prediction in 2-Portal Endoscopic Carpal Tunnel Release for Idiopathic Carpal Tunnel Syndrome

PURPOSE This study aimed to identify technical difficulties encountered during 2-portal endoscopic carpal tunnel release (ECTR) and to determine their incidence. Furthermore, we assessed the possibility of preoperatively predicting such technical difficulties. METHODS We retrospectively reviewed the records of 311 hands of 311 patients with idiopathic carpal tunnel syndrome who underwent ECTR with our modified Chow 2-portal technique. Any technical difficulties during the procedure were reviewed and correlated with preoperative physical findings, nerve conduction studies, and magnetic resonance imaging findings, by use of the t test, χ(2) test, and binary regression analysis. RESULTS One or more difficulties were encountered in 139 of 311 hands (44.7%), whereas surgery in the remaining 172 hands (55.3%) was performed without any difficulties. Technical difficulties encountered were as follows: tight access in 61 hands, difficulty in identifying the distal part of the transverse carpal ligament through the exit portal in 35 hands, synovial tissue being caught at the cannula tip when pulling it out of the carpal tunnel in 39 hands, steep angle of the cannula assembly with difficulty in emerging from the exit portal in 29 hands, and other difficulties. Postoperative worsening of symptoms was observed in 8 hands (2.6%), in all of which technical difficulties were encountered. Tight access was noted in younger patients and those with a small cross-sectional area at the hook-of-hamate level. The entire ECTR procedure for older female patients was more likely to be easily performed. CONCLUSIONS The surgeon may face a variety of technical difficulties during ECTR. Technical difficulties were most often encountered during introduction of the cannula assembly into the carpal tunnel and pulling it out of the exit portal. Older female patients may be the best candidates for 2-portal ECTR. LEVEL OF EVIDENCE Level IV, therapeutic case series.

The Effect of Vascular Pedicle Preservation on Blood Flow and Clinical Outcome Following Ulnar Nerve Transposition

PURPOSE To evaluate the efficacy of a technique to preserve the extrinsic vascular supply to the ulnar nerve after transposition and its effect on blood flow and clinical outcome. METHODS We included 36 patients with cubital tunnel syndrome. The patients were randomly selected to undergo vascular pedicles-sparing surgery for anterior ulnar nerve transposition (VP group) or nerve transposition and artery ligation (non-VP group). Blood flow to the ulnar nerve was estimated intraoperatively at 3 locations in the cubital tunnel before and after transposition using a laser Doppler flowmeter. Clinical results at 3, 6, and 12 months after surgery were also compared between the 2 groups. RESULTS The blood flow before ulnar nerve transposition was not significantly different between the groups. Blood flow at all 3 locations after the ulnar nerve transposition was significantly higher in the VP group than in the non-VP group. Blood flow in the non-VP group reduced to values between 28% and 52% from the pre-transposition baseline values. After surgery, no significant differences were observed in the clinical results between the groups, except for the Disabilities of the Arm, Shoulder and Hand scores at 12 months after surgery, which was greater in the non-VP group. CONCLUSIONS The procedure of preserving the extrinsic vascular pedicles can prevent compromise of blood flow to the ulnar nerve immediately after nerve transposition. However, this procedure had no correlation to improved recovery of ulnar nerve function after surgery. TYPE OF STUDY/LEVEL OF EVIDENCE Therapeutic II.

Effects of repeated crush injuries on motor functional recovery of the sciatic nerve.

Abstract Objectives: The present study was conducted to examine whether repeated crush injuries have significant effects on motor functional recovery of peripheral nerves. Methods: Repeated crush injuries of the sciatic nerve were inflicted on adult rats at 1-week intervals, and functionality of the sciatic nerve was assessed by the static sciatic index each week for 8 weeks after the final injury. To determine the effects of repeated crush injuries on motor functional recovery of the sciatic nerve, tibialis anterior muscle fibers from single and triple crush injuries were examined, and fiber size and fiber reinnervation during the 2- to 4-week period after the final injury were measured. Results: Compared to single crush injuries, which completely recovered by post-injury week 4, double crush injuries resulted in retarded, but complete recovery by post-injury week 6, whereas triple crush injuries resulted in marked retardation in the regenerative process with incomplete recovery during week 8 of the experimental period. Muscle fiber size for rats with triple crush did not recover to normal range at post-injury week 4, despite its normal size for rats with single crush. The rate of reinnervation increased prominently between post-injury weeks 2 and 3 in both injuries, but the rate with triple crush was lower than that with single crush at post-injury week 3. Discussion: These results, which contradict those of a previous study that reported early functional recovery, indicate that repeated crush injuries inhibit motor functional recovery of the damaged sciatic nerve, as evidenced by delayed and incomplete regeneration, atrophied muscle fibers, and delayed reinnervation.

Myostatin promotes tenogenic differentiation of C2C12 myoblast cells through Smad3

Myostatin, a member of the transforming growth factor‐β (TGF‐β) superfamily, is expressed in developing and adult skeletal muscle and negatively regulates skeletal muscle growth. Recently, myostatin has been found to be expressed in tendons and increases tendon fibroblast proliferation and the expression of tenocyte markers. C2C12 is a mouse myoblast cell line, which has the ability to transdifferentiate into osteoblast and adipocyte lineages. We hypothesized that myostatin is capable of inducing tenogenic differentiation of C2C12 cells. We found that the expression of scleraxis, a tendon progenitor cell marker, is much higher in C2C12 than in the multipotent mouse mesenchymal fibroblast cell line C3H10T1/2. In comparison with other growth factors, myostatin significantly up‐regulated the expression of the tenogenic marker in C2C12 cells under serum‐free culture conditions. Immunohistochemistry showed that myostatin inhibited myotube formation and promoted the formation of spindle‐shaped cells expressing tenomodulin. We examined signaling pathways essential for tenogenic differentiation to clarify the mechanism of myostatin‐induced differentiation of C2C12 into tenocytes. The expression of tenomodulin was significantly suppressed by treatment with the ALK inhibitor SB341542, in contrast to p38MAPK (SB203580) and MEK1 (PD98059) inhibitors. RNAi silencing of Smad3 significantly suppressed myostatin‐induced tenomodulin expression. These results indicate that myostatin has a potential role in the induction of tenogenic differentiation of C2C12 cells, which have tendon progenitor cell characteristics, through activation of Smad3‐mediated signaling.