Analysis of the thenar muscles with ultrasound shear wave elastography: Reliability and preliminary findings.

INTRODUCTION/AIMS: Ultrasound shear wave elastography (SWE) of the thenar muscles has the potential to provide a simple and noninvasive assessment of the severity of carpal tunnel syndrome (CTS), but its reliability is unknown. The purpose of this study was to assess the intra- and inter-rater reliability of SWE measurements of the elastic modulus of individual thenar muscles, to assess their suitability for clinical application. METHODS: Fourteen healthy volunteers, seven male and seven female, participated in this study. The elastic modulus of the thenar muscles was measured with SWE, with two independent examiners to assess inter-rater reliability. The first examiner also performed a second measurement after an interval of least 1 day to assess intra-rater reliability. Reliability was evaluated using an intraclass correlation coefficient (ICC) and 95% confidence interval (CI). RESULTS: For the abductor pollicis brevis (APB) and opponens pollicis (OPP), the CI of ICC in intra-rater reliability was 0.47-0.85 and 0.56-0.88, respectively. The CI of ICC in inter-rater reliability was 0.27-0.78 for the APB and 0.22-0.76 for the OPP. The ICCs of intra- and/or inter-rater reliability of other thenar muscles were less than 0.5. DISCUSSION: In this study, SWE evaluations of thenar muscles were quite variable in terms of their reliability. A larger study will be needed to determine the source of this variability, improve reliability, and assess the value of SWE in the evaluation of the severity of CTS.

Fatigability of the thenar muscles using electrical nerve stimulation with fixed stimuli count, while varying the frequency and duty cycle.

Our aim was to compare three electrical stimulation protocols (P20, P30 and P40), with the same number of stimuli, but different stimulation frequencies (20, 30 and 40 Hz, respectively) and duty cycles [1.2:1.2 s (continuous), 0.8:1.2 s (intermittent) and 0.6:1.2 s (intermittent), respectively). Twitch force and the peak-to-peak M-wave amplitude of the thenar muscles were measured before, during and after each protocol at 1-40 Hz in random order. Twelve healthy adults (23-41 years old) were examined for each protocol in random order and in separate sessions. P20 elicited the highest mean force, and P40 the lowest decrease in percent force at the end of the protocol. Force evoked at 1 and 10 Hz decreased less after P40, compared with P20 and P30. The M-wave amplitude was significantly reduced throughout all protocols, with the largest decrease observed during P30. Although an increase in frequency typically induced earlier and greater decrement in force, this was compensated or even reversed by increasing the interval between each stimulation train, while keeping the number of pulses per stimulation cycle constant. The lesser decrease in M-wave amplitude during P40 compared with P20 indicates that longer between-train intervals may help maintaining the integrity of neuromuscular propagation.

Shear-wave elastography evaluation of thenar muscle in carpal tunnel syndrome.

PURPOSE: We aim to evaluate the shear wave velocity (SWV) of the thenar muscle as an adjunct diagnostic tool for carpal tunnel syndrome (CTS). METHODS: Ninety-two wrists with CTS and 30 control wrists without CTS underwent ultrasonographic evaluation of thenar muscle and median nerve including shear-wave elastography. Cross sectional area (CSA) of medial nerve and SWV of thenar muscle and median nerve were evaluated. CTS patients were assessed for Boston CTS, Padua CTS, modified Hirani grading scores, and nerve conduction study (NCS). SWVs, CSA, and NCS parameters were compared between two groups. RESULTS: The SWVs of thenar muscle and median nerve (p < 0.001, respectively), and CSA of median nerve (p < 0.001) were more significantly greater in patients with CTS than in controls. The SWV of median nerve was moderately correlated with CSA of median nerve (r = 0.35, p < 0.001) and modified Hirani CTS score (r = 0.35, p < 0.001). The SWV of thenar muscle was inversely correlated with modified Hirani CTS score (r = -0.21, p = 0.04). CONCLUSION: The SWV of thenar muscle and median nerve of CTS were significantly increased compared to that of control, and significantly negatively correlated with NCS parameters (modified Hirani CTS score). SWVs may be used as an adjunct diagnostic tool for CTS.

Sonographic evaluation of the abductor pollicis brevis muscle reflects muscle strength recovery after carpal tunnel release.

PURPOSE: This study aimed to examine the associations between sonographic measurements of the abductor pollicis brevis (APB), grip and pinch strength, and distal motor latency (DML) in patients with carpal tunnel syndrome (CTS) before and after surgery. METHODS: We prospectively studied patients (46 hands) who underwent 1 year of postoperative follow-up after endoscopic carpal tunnel release. The patients underwent ultrasound (US) scans, grip and pinch strength assessment, a nerve conduction study, and patient-reported outcome measures (Carpal Tunnel Syndrome Instrument and Michigan Hand Outcomes Questionnaire) before and 1 year after surgery. The standardized response mean was calculated to compare the sensitivity of clinical changes in these measurements. RESULTS: US measurements (thickness of the APB and the cross-sectional area of the APB) and muscle strength (grip strength, key pinch, and tip pinch) were greater, and DML was reduced after surgery compared with those before surgery (all P < 0.05). Patient-reported outcome measures also showed clinical improvement 1 year after surgery (P < 0.05). US measurements of the APB were significantly correlated with grip and pinch strength (all P < 0.05), but not with DML, before surgery and 1 year after surgery. The standardized response mean showed a large responsiveness for US measurements of the APB and patient-reported outcome measures. CONCLUSION: US evaluation of the APB after CTS can complement the evaluation of grip and pinch strength in the clinical setting. Postoperative recovery of the APB leads to improved motor dysfunction in CTS. Therefore, US measurement of the APB could be a useful tool for evaluating motor function.

Preoperative Evaluation of Thenar Muscles in Carpal Tunnel Syndrome by Ultrasonography.

This article aims to evaluate the usefulness of ultrasonography for the measurement of thenar muscles in carpal tunnel syndrome (CTS). A total of 85 patients with CTS who had a carpal tunnel release procedure were included in this study. The transducer was applied onto the palmar surface of the hand perpendicularly to the longitudinal axis of the first metacarpal bone. Thenar atrophy was evaluated visually and classified using the visual grading scale. A nerve conduction test was performed and classified according to the electrophysiological severity scale. This technique is more precise than visual evaluation because it is a quantitative assessment.

Ultrasonography in patients with congenital thenar hypoplasia (Cavanagh syndrome) and co-morbid carpal tunnel syndrome.

OBJECTIVE: Patients with congenital thenar hypoplasia (Cavanagh syndrome) may undergo surgical intervention with a mistaken diagnosis of severe carpal tunnel syndrome. Conversely, patients with Cavanagh syndrome can develop co-morbid median nerve entrapment at the carpal tunnel later in life and may go untreated. This study is aimed at evaluating the role of ultrasonography in confirming/ruling out median nerve entrapment at the carpal tunnel in patients with Cavanagh syndrome. METHODS: 6 patients with Cavanagh syndrome were identified during a 10-year period from among patients referred for preoperative electrodiagnostic confirmation of carpal tunnel syndrome. All patients underwent ultrasound imaging as well as electrodiagnostic studies including motor conduction study of the median nerve with recording electrodes over the lumbrical muscles. RESULTS: Age range of patients was 39-76. The right hand was affected in 5 and left hand in 1 patient. Electrodiagnostic studies (EDX) confirmed carpal tunnel syndrome in 4 of the 6 patients. In one patient the nerve conduction studies were non-diagnostic due to absence of compound muscle action potential (CMAP) over the thenar, and the 2nd lumbrical muscles and absent sensory nerve action potentials (SNAP). Ultrasound images confirmed entrapment of median nerve at the carpal tunnel in all 5 patients. The sixth patient was mistakenly diagnosed with severe carpal tunnel syndrome by the referring physician, based on the thenar atrophy; the median nerve was normal in both ultrasound and electrodiagnostic studies. CONCLUSION: Ultrasound was useful for confirming/ruling out comorbid carpal tunnel syndrome in all 6 patients with Cavanagh syndrome. SIGNIFICANCE: Ultrasound complements electrodiagnostic study findings in patients with congenital thenar hypoplasia and comorbid carpal tunnel syndrome. It is even more valuable when EDX findings are non-diagnostic due to absent CMAP and SNAP.

Single incision thenar muscle reconstruction using the free functional pronator quadratus flap.

BACKGROUND: Injuries to the thenar muscle mass or the thenar branch of the median nerve and resulting loss of thumb opposition lead to a massive impairment of hand function. For decades, reconstructive approaches were based on tendon transfers. To broaden the reconstructive repertoire, we present the free functional pronator quadratus flap as a viable alternative for functional reconstruction and provide a specification for its indication. We demonstrate our surgical technique to a single incision reconstruction using the free functional pronator quadratus flap. Based on a series of three patients, which were analyzed for hand function using Kapandji's score and the angle of Bourrel, grip strength and nerve conduction velocity in a two year follow up, we present an indication algorithm. RESULTS: After successful reinnervation of all flaps, we found an improvement of Kapandji's score from 4.3 ± 0.94 preoperatively, to 8.7 ± 0.47 after two years. Accordingly, the angle of Bourrel decreased from 75.75 ± 3.45 degrees to 36.96 ± 3.68 degree. Grip strength also improved from 14 ± 2.2 kg to 26.2 ± 1.2 kg. No impairment of wrist pronation was observed. CONCLUSION: We found excellent functional recovery of thumb opposition and strength, showing similar or even superior results compared to results from tendon transfers. With the benefit of a single incision surgery and therefore minimal donor site morbidity, this free functional muscle transfer is a viable alternative to classic tendon transfers.

Palmar Musculature: Does It Affect the Development of Carpal Tunnel Syndrome? A Pilot Study.

Background The etiology of carpal tunnel syndrome (CTS) is multifactorial. Static mechanical characteristics of CTS have been described, but dynamic (muscular) parameters remain obscure. We believe that musculature overlying the transverse carpal ligament may have an effect on carpal tunnel pressure and may explain the prevalence of CTS in manual workers. Questions/Purposes To utilize magnetic resonance imaging (MRI) imaging to estimate the amount of muscle crossing the area of the carpal tunnel and to compare these MRI measurements in patients with and without documented CTS. Methods A case-control study of wrist MRI scans between January 1, 2018, and December 1, 2019, was performed. Patients with a diagnosis of CTS were matched by age and gender with controls without a diagnosis of CTS. Axial MRI cuts at the level of the hook of the hamate were used to measure the thenar and hypothenar muscle depth overlying the carpal tunnel. Muscle depth was quantified in millimeters at three points: midcapitate, capitate-hamate border, capitate-trapezoid border. Average depth was calculated by dividing the cross-sectional area (CSA) by the transverse carpal ligament width. Statistical analysis included Student's t -test, chi-square test, and Pearson's correlation coefficient calculation. Results A total of 21 cases and 21 controls met the inclusion criteria for the study. There were no significant differences in demographics between case and control groups. The location and depth of the musculature crossing the carpal tunnel were highly variable in all areas evaluated. A significantly positive correlation was found between proximal median nerve CSA and muscle depth in the capitate-hamate area (correlation coefficient = 0.375; p = 0.014). CSA was not significantly associated with chart documented CTS. Conclusions We found large variability in our measurements. This likely reflects true anatomical variation. The significance of our findings depends on the location of the muscles and the line of pull and their effect on the mechanics of the transverse carpal ligament. Future research will focus on refining measurement methodology and understanding the mechanical effect of the muscular structure and insertions on carpal tunnel pressure. Level of Evidence This is a Level 3, case-control study.

When is needle examination of thenar muscle necessary in the evaluation of mild and moderate carpal tunnel syndrome?

OBJECTIVES: This study aims to evaluate the predictors of standard nerve conduction study (NCS) parameters in determining the presence of axonal loss by means of spontaneous activity in patients with mild and moderate carpal tunnel syndrome (CTS). PATIENTS AND METHODS: Between May 2015 and April 2018, a total of 118 patients (11 males, 107 females; mean age: 52.3±10.6 years; range, 27 to 79 years) who underwent electrophysiological studies and were diagnosed with CTS were included. Demographic data of the patients including age, sex, and symptom duration were recorded. Electrodiagnostic studies were performed in all patients. All the needle electromyography (EMG) findings were recorded, but only the presence or absence of spontaneous EMG activities was used as the indicator of axonal injury. RESULTS: In 37 (31.4%) of the patients, spontaneous activity was detected at the thenar muscle needle EMG. No spontaneous activity was observed in any of 43 (36.4%) patients with normal distal motor latency (DML). There were significant differences in DMLs, compound muscle action potential (CMAP) amplitudes, sensory nerve action potentials amplitudes, and sensory nerve conduction velocities between the groups with and without spontaneous activity (p<0.05). The multiple logistic regression analysis revealed that DML was a significant independent risk variable in determining presence of spontaneous activity. The most optimal cut-off value for median DML was calculated as 4.9 ms. If the median DML was >4.9 ms, the relative risk of finding spontaneous activity on thenar muscle needle EMG was 13.5 (95% CI: 3.6-51.2). CONCLUSION: Distal motor latency is the main parameter for predicting the presence of spontaneous activity in mild and moderate CTS patients with normal CMAP. Performing needle EMG of the thenar muscle in CTS patients with a DML of >4.9 ms may be beneficial to detect axonal degeneration in early stages.

Thenar Muscle Oxygen Saturation Levels: A Surrogate for Central Venous Oxygen Saturation?

PURPOSE: Shock is associated with increased tissue oxygen extraction. Near-infrared spectroscopy-derived thenar muscle tissue oxygenation (StO2) levels can provide an estimate of the oxygen supply-demand balance at the tissue level. We hypothesized that thenar StO2 levels would correlate with central venous oxygen saturation (ScvO2) levels, the gold standard for global tissue oxygen extraction in the body. METHODS: We prospectively enrolled 60 pediatric subjects admitted to pediatric intensive care unit or who underwent cardiac catheterization from September 2015 to March 2018. Thenar StO2 levels were measured using the InSpectra StO2 probe. Concurrent measurements of ScvO2 and peripheral tissue oxygenation (StO2) were achieved through simultaneous testing. For ScvO2, a central line placed in the superior vena cava was utilized for serum specimen collection, while the InSpectra probe recorded StO2 measurements from the thenar eminence of the patient's right hand. RESULTS: Sixty observations of thenar StO2 and ScvO2 levels were derived from 60 subjects. Mean thenar StO2 levels were 74.72 ± 11.18% and displayed significant correlation with paired ScvO2 measurements ( m = 72.17 ± 9.77%; ρ = 0.317, P = .018). Correlation was much more significant in subjects who were not on mechanical ventilatory support as opposed to those who were on it ( ρSORA = 0.496, PSORA = .003, vs ρVENT = 0.161, PVENT = .433). A thenar StO2 of 73% had a sensitivity of 80% and a specificity of 77.8% in predicting an ScvO2 of less than 65%. CONCLUSION: This is the first study to report correlation of thenar StO2 and ScvO2 levels in children. Our study results show a significant correlation between these levels. Thenar StO2 measurements may have a role in the bedside management of critically ill children in whom ScvO2 monitoring is not available.

Does the duration of motor imagery affect the excitability of spinal anterior horn cells?

PURPOSE: Motor imagery, the process of imagining a physical action, has been shown to facilitate the excitability of spinal anterior horn cells. In the acute phase after a stroke, the excitability of spinal anterior horn cells is significantly reduced, which leads to motor deficits. This loss of movement can be prevented by increasing the excitability of spinal anterior horn cells immediately following an injury. Motor imagery is an effective method for facilitating the excitability of spinal anterior horn cells in patients with impaired movement; however, the optimal duration for motor imagery is unclear. MATERIALS AND METHODS: To investigate time-dependent changes in spinal anterior horn cell excitability during motor imagery, healthy adult participants were recruited to measure the F-wave, an indicator of anterior horn cell excitability. F-waves were measured from participants at baseline, during motor imagery, and post-motor imagery. During motor imagery, participants imagined isometric thenar muscle activity at 50% maximum voluntary contraction for 5 min. F-waves were measured at 1, 3, and 5 min after beginning motor imagery and analysed for persistence and F/M amplitude ratio. RESULTS: Persistence and F/M amplitude ratios at 1- and 3-min after motor imagery initiation were significantly greater than at baseline. The persistence and F/M amplitude ratio at 5-min after motor imagery initiation, however, was comparable to baseline levels. CONCLUSION: Therefore, 1 to 3 min of motor imagery is likely sufficient to facilitate the excitability of spinal anterior horn cells.

Anatomical Relationships between Muscles Overlying Distal Transverse Carpal Ligament and Thenar Motor Branch of the Median Nerve.

BACKGROUND: The purpose of the current study is to investigate anatomical relationships between the muscle overlying the distal transverse carpal ligament (TCL) and the thenar motor branch of the median nerve. METHODS: Of the 192 wrists that underwent open carpal tunnel release, a muscle belly overlying the TCL was observed on the distal margin of TCL in 25 wrists and ligament exposure could not be achieved without transection of it. We recorded surgical findings of these 25 wrists. The origin of the recurrent motor branch arising from the major median nerve was marked on the axial and coronal section diagrams of the wrist. RESULTS: The presence of muscle overlying the TCL was seen in 25 wrists (21 patients, 13%). The locations of origin were distributed not only on the radial side but anterior or ulnar side of the major median nerve. Abnormal branches originated from the unusual side in 14 cases (56% of those with a muscle overlying the TCL): central-anterior side in eight cases, ulnar-anterior side in five cases, and ulnar side in one case. These anomalous branches were frequently associated with the muscle belly overlying the TCL in our study regardless of the origin site. The branches were prone to cut if careless midline incision along the third web space was performed. Unusual origin and aberrant pathway of the recurrent thenar motor branch were associated with the presence of a muscle overlying the TCL. CONCLUSIONS: A thorough knowledge of the standard and variant anatomy of the muscle belly and recurrent motor branch in the carpal tunnel is fundamental to prevention of complications such as muscle wasting or atrophy by iatrogenic motor branch injury during carpal tunnel release.

Anatomical Relationships between Muscles Overlying Distal Transverse Carpal Ligament and Thenar Motor Branch of the Median Nerve

BACKGROUND: The purpose of the current study is to investigate anatomical relationships between the muscle overlying the distal transverse carpal ligament (TCL) and the thenar motor branch of the median nerve. METHODS: Of the 192 wrists that underwent open carpal tunnel release, a muscle belly overlying the TCL was observed on the distal margin of TCL in 25 wrists and ligament exposure could not be achieved without transection of it. We recorded surgical findings of these 25 wrists. The origin of the recurrent motor branch arising from the major median nerve was marked on the axial and coronal section diagrams of the wrist. RESULTS: The presence of muscle overlying the TCL was seen in 25 wrists (21 patients, 13%). The locations of origin were distributed not only on the radial side but anterior or ulnar side of the major median nerve. Abnormal branches originated from the unusual side in 14 cases (56% of those with a muscle overlying the TCL): central-anterior side in eight cases, ulnar-anterior side in five cases, and ulnar side in one case. These anomalous branches were frequently associated with the muscle belly overlying the TCL in our study regardless of the origin site. The branches were prone to cut if careless midline incision along the third web space was performed. Unusual origin and aberrant pathway of the recurrent thenar motor branch were associated with the presence of a muscle overlying the TCL. CONCLUSIONS: A thorough knowledge of the standard and variant anatomy of the muscle belly and recurrent motor branch in the carpal tunnel is fundamental to prevention of complications such as muscle wasting or atrophy by iatrogenic motor branch injury during carpal tunnel release.

Evaluation of thenar muscles by MRI in carpal tunnel syndrome.

In the present study, the thenar muscles were evaluated using magnetic resonance imaging (MRI), in addition, the correlations between thenar muscle changes, clinical findings and electrodiagnostic results from patients with carpal tunnel syndrome were investigated. The subjects were 13 patients (17 wrists) who were clinically diagnosed with carpal tunnel syndrome. In all patients, a medical history was obtained and physical examination was performed, in addition to assessment using the Kapandji scoring system, visual analogue scale (VAS), quick-disabilities of the arm, shoulder and hand (Q-DASH) score, electrodiagnostic results of the median nerve, and MRI of the thenar muscles. Thenar muscle volume was not significantly correlated with clinical data or the electrodiagnostic results. The thenar muscle major axis was significantly correlated with grasp power (P<0.05) and the Kapandji score (P<0.05), while the thenar muscle minor axis was significantly correlated with abductor pollicis brevis distal motor latency (APB DML) (P<0.01). In addition, the thenar muscle minor axis/thenar muscle major axis ratio was significantly correlated with APB DML and Kanatani's stage. Notably, thenar muscle thinness was significantly correlated with the severity of electrodiagnostic changes, while the grasp power and Kapandji score were correlated with thenar muscle thickness. Furthermore, it was demonstrated that thenar muscle thinness was significantly correlated with the severity of electrodiagnostic changes; in addition, there was a significant correlation between the thenar muscle major axis and the grasp power or Kapandji score. Taken together, these results revealed that thenar muscle atrophy did not affect patient-based assessments, including VAS and Q-DASH, but reflected electrodiagnostic results, particularly DML and severity. The results of the present study suggest that thenar muscle atrophy can be used to estimate the severity of carpal tunnel syndrome.

Relation between distal motor latency delay and sensory action potential absence of the median nerve in carpal tunnel syndrome.

OBJECTIVE: To elucidate the cutoff value for distal motor latency (DML) at which sensory nerve action potentials (SNAPs) are absent in carpal tunnel syndrome (CTS) patients. METHOD: We examined 157 hands in 129 patients with CTS retrospectively. We classified the patients according to whether SNAPs were successfully obtained. Group A consisted of hands with SNAPs, while Group B consisted of hands without SNAPs. The cutoff value for DML was determined by receiver-operating characteristic curve analysis. We enrolled 130 hands with CTS for the analysis, because measurements were successful in 130 hands for compound muscle action potentials and in 82 hands for SNAPs from a total of 157 hands investigated. RESULTS: A significant correlation was observed between DML and SCV (P<0.0001, R*2=0.40). The most discriminative cutoff value for DML was 7.7ms, resulting in a sensitivity of 79.6% and specificity of 79.3%. CONCLUSION: Cases in which SNAPs are evoked despite a DML longer than 7.7ms should raise suspicion.

Ileocecal adenocarcinoma with overexpression of P53 protein metastasized to the thenar muscle: report of a rare case and review of literature.

Metastatic malignancies of the hand are rare and metastases to the skeletal muscle from the gastrointestinal system are even much rare. Here we present a case of metastatic ileocecal adenocarcinoma to the thenar muscle, which is the first report of thenar muscle metastasis from ileocecal adenocarcinoma with P53 mutation. To date, only two other cases of thenar muscle metastasis have been documented, one is from squamous cell carcinoma of the lung and the other is from rectal carcinoma. The present 67-year-old Chinese man of poorly differentiated adenocarcinoma of the ileocecal region developed metastatic carcinoma in the right thenar eminence, which presented with swelling and pain. Magnetic resonance imaging of the right hand revealed a well-defined enhanced mass in the right thenar muscle. It was proved to be metastatic adenocarcinoma using core needle biopsy, which was supported to be gastrointestinal origination by positive immunoreaction with CDX2. Positive immunoreaction with P53 protein indicated the poor prognosis of the patient. Further systemic evaluation including computerized tomography scans revealed extensive metastases to liver, right kidney, right abdominal wall, left axillary and right subclavicular lymph nodes, and skin of the right thigh. Treatment was given with palliative systemic chemotherapy. After 8 cycles of chemotherapy, the swelling and pain of the right thenar were ameliorated, and the patient regained full use of his right hand and his quality of life was improved. The patient died of liver metastasis 9 months after the diagnosis of the right thenar metastasis. In conclusion, here we display a case of thenar skeletal muscle metastasis from P53 mutated ileocecal adenocarcinoma, who survived 9 months after diagnosis of the rare metastasis. If an oncological patient presents an intramuscular mass, muscle metastasis must be included in the differential diagnosis. Metastatic hand tumors generally indicate systemic spread, so the treatment is usually palliative and the prognosis is poor. The primary objective of treatment is improvement of the patient's quality of life.

Early surgical treatment of pronator teres syndrome.

We report a rare case of pronator teres syndrome in a young female patient. She reported that her right hand grip had weakened and development of tingling sensation in the first-third fingers two months previous. Thenar muscle atrophy was prominent, and hypoesthesia was also examined on median nerve territory. The pronation test and Tinel sign on the proximal forearm were positive. Severe pinch grip power weakness and production of a weak "OK" sign were also noted. Routine electromyography and nerve conduction velocity showed incomplete median neuropathy above the elbow level with severe axonal loss. Surgical treatment was performed because spontaneous recovery was not seen one month later.

Early Surgical Treatment of Pronator Teres Syndrome

We report a rare case of pronator teres syndrome in a young female patient. She reported that her right hand grip had weakened and development of tingling sensation in the first-third fingers two months previous. Thenar muscle atrophy was prominent, and hypoesthesia was also examined on median nerve territory. The pronation test and Tinel sign on the proximal forearm were positive. Severe pinch grip power weakness and production of a weak "OK" sign were also noted. Routine electromyography and nerve conduction velocity showed incomplete median neuropathy above the elbow level with severe axonal loss. Surgical treatment was performed because spontaneous recovery was not seen one month later.

Correlating ultrasound findings of carpal tunnel syndrome with nerve conduction studies.

INTRODUCTION: The aim of this study was to make correlations between ultrasonographic measurements of thenar muscle and flexor retinaculum and nerve conduction studies (NCS) in carpal tunnel syndrome (CTS). METHODS: Ultrasound and NCS were performed on 92 wrists with CTS and on 40 wrists from healthy individuals. Ultrasound of thenar and hypothenar muscles, flexor retinaculum, and median nerve were assessed. The ultrasonographic findings were compared between the 2 groups, and correlation analyses between median latency and ultrasonographic findings were performed. RESULTS: Motor latency correlated positively with flexor retinaculum thickness (FRT) and negatively with the ratio of thenar to hypothenar muscle. FRT and motor latency were found to be increased significantly in CTS. The ratio of thenar to hypothenar muscle was found to be decreased significantly in CTS compared with controls. CONCLUSIONS: The ultrasonographic findings of FRT and thenar muscle reflect the severity of disease in patients with CTS and are valuable for the diagnosis of CTS.

The exploded hand syndrome: a report of five industrial injury cases.

The term 'exploded hand syndrome' refers to a specific type of crush injury to the hand in which a high compressive force excessively flattens the hand leading to thenar muscle extrusion through burst lacerations. Out of 89 crushed hands seen over a period of seven years, only five had exploded hand syndrome. They were all male industrial workers ranging in age between 24 and 55 years. All patients had thenar muscle extrusion. Other concurrent injuries included fractures/dislocations, compartment syndrome, and ischaemia. All patients were treated by excision of the extruded intrinsic muscles, as well as primary management of concurrent injuries. All patients had functional assessment including: motor power and sensory testing, range of motion of hand joints, and the quick DASH score. Objective testing showed reduced sensibility in the thumb, reduced grip strength (mean 52% of contralateral hand), reduced pinch strength (mean of 27% of contralateral hand), reduced thumb opposition (the mean Kapandji Score was 5 out of 10), and deficits in the range of motion of the metacarpophalangeal and interphalangeal joints of the thumb. The quick DASH score ranged from 11 to 49 and only two patients were able to go back to regular manual work.