Evaluation of sensory function after median nerve decompression in carpal tunnel syndrome using the current perception threshold test

Comparison of Patient-Reported Outcomes With or Without Prophylactic Carpal Tunnel Release After Distal Radius Fracture Stabilization

Distal radius fractures (DRFs) are frequently complicated by acute carpal tunnel syndrome (CTS), which, if unrecognized, can cause permanent median neuropathy. Some surgeons recommend "prophylactic" carpal tunnel release (CTR) during open reduction and internal fixation (ORIF) of DRF. Patient-reported outcomes (PROs) and safety data regarding prophylactic vs symptomatic CTR strategies during DRF fixation are lacking. We conducted a retrospective review of two management strategies for DRFs at our institution (2017 to 2019). Group 1 consisted of patients operated on by two surgeons performing ORIF and symptomatic CTR only for acute CTS. Group 2 consisted of patients operated on by a third surgeon performing ORIF and prophylactic CTR on all patients irrespective of median nerve symptoms. The PROs included QuickDASH Wrist and PROMIS physical/mental health preoperatively vs at final follow-up. Demographic information, complications, and return to the operating room were recorded. Group 1 (36 patients) and group 2 (76 patients) were demographically similar. The mechanism of injury was more severe in group 1 (P<.05), but preoperative PROs were similar between the two groups. Eight patients (22.2%) in group 1 had symptomatic CTR for acute CTS. Significant improvement occurred within both groups from preoperative to final follow-up for PROMIS physical function and QuickDASH Wrist scores (P<.05). Intergroup PROs were not significantly different at either time point. One patient in group 1 (2.8%) and 2 patients in group 2 (2.6%) returned to the operating room due to median nerve symptoms (P>.05). A prophylactic CTR strategy is not associated with improved PROs compared with a symptomatic strategy during ORIF of DRF. [Orthopedics. 2023;46(6):e362-e368.].

Utility of Ultrasound for Identifying Median Nerve Changes Indicative of Acute Carpal Tunnel Syndrome After Distal Radius Fracture

Purpose

Ultrasound offers a fast and inexpensive way to evaluate the median nerve. However, there is a paucity of data assessing ultrasound in acute trauma. Our study aimed to characterize median nerve changes indicative of acute carpal tunnel syndrome (ACTS) in a cadaveric distal radius fracture (DRF) model.

Methods

We used 10 upper-extremity specimens. We induced ACTS (carpal tunnel pressure >40 mm Hg) in a distraction-only model and then used a DRF model as a neutral position, under traction, or wrist extension. We measured the median nerve cross-sectional area (CSA), height, and width with ultrasound in each model. We used a novel calculation, height-width ratio (HWR), to describe nerve shape. A low HWR indicates an elliptical shape; as the HWR increases toward one, the shape becomes more circular. The CSA measurements and HWR at pressures >40 mm Hg were used to calculate a 95% confidence interval, which defined the threshold for ACTS.

Results

Wrist distraction created carpal tunnel pressures >40 mm Hg in all specimens. Distraction increased CSA compared with baseline (9.1 ± 0.9 mm² vs 6.3 ± 1.2 mm², P < .001). Under ACTS-level pressures, the thresholds for CSA and HWR were 8.5 mm² and 0.41, respectively. HWR significantly increased with distraction compared with baseline (0.47 ± 0.10 vs 0.28 ± 0.09, P = .006). Most neutral DRF models (n = 8, 80%) met the CSA threshold for ACTS, whereas all specimens with a DRF extended or under traction had CSAs above the ACTS threshold. Compared to the baseline, the shape of the median nerve was more circular in all DRFs, including neutral (0.28 ± 0.09 vs 0.39 ± 0.13), under traction (0.43 ± 0.09), and extended (0.45 ± 0.09).

Conclusions

ACTS should be suspected in patients with median nerves demonstrating increased CSA and adopting a more circular shape. Fracture positioning impacts median nerve CSA with wrist extension, causing the greatest change. Median nerve HWR may offer an easier ultrasonographic alternative to CSA.

Type of study/level of evidence

Diagnostic III.

Carpal Tunnel Release Performed during Distal Radius Fracture Surgery

Background  Carpal tunnel release (CTR) may be concomitantly performed along with distal radius fracture open reduction internal fixation (DRF ORIF) to prevent carpal tunnel syndrome; however, there is little to no literature investigating the rate, risk factors, and complications associated with CTR. Questions/Purposes  The purpose was to determine (1) the rate of CTR performed at time of DRF ORIF, (2) factors associated with CTR, and (3) whether CTR was associated with any complications. Patients and Methods  In this case-control study, adult patients who underwent DRF ORIF from 2014 to 2018 were identified from a national surgical database. Two cohorts were analyzed, (1) patients with CTR and (2) patients without CTR. Preoperative characteristics and postoperative complications were compared with determine factors associated with CTR. Results  Of the 18,466 patients, 769 (4.2%) had CTR. Rates of CTR in patients with intra-articular fractures with two or three fragments were significantly higher than the rate of CTR for patients with extra-articular fractures. Underweight patients underwent CTR at a significantly lower rate compared with overweight and obese patients. The American Society of Anesthesiologists ≥3 was associated with a higher rate of CTR. Male and older patients were less likely to have CTR. Conclusion  The rate of CTR at time of DRF ORIF was 4.2%. Intra-articular fractures with multiple fragments were strongly associated with CTR at time of DRF ORIF, while being underweight, elderly, and male were associated with lower rates of CTR. These findings should be considered when developing clinical guidelines to assess the need for CTR in patients undergoing DRF ORIF. This is a retrospective case control study and reflects level of evidence III.

A Systematic Review of the Outcomes of Carpal Ligament Release in Severe Carpal Tunnel Syndrome

PURPOSE

Indications for surgical treatment of severe carpal tunnel syndrome (CTS) are controversial. The aim of this study was to review the outcomes reported in the literature of carpal tunnel release in patients with severe CTS.

METHODS

A systematic review of the outcomes of carpal tunnel release in patients with severe CTS was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Outcome measures included change in symptoms, sensation (2-point discrimination, light touch), thenar atrophy, strength (power and pinch grip), electrophysiology, median nerve morphology, and patient-reported outcome measures. Outcomes are reported by ranges of the percentage of patients/hands improved in the included studies.

RESULTS

Thirty-eight papers were selected, representing 2,531 patients and 2,712 hands. Demographic information on age and sex were available for a total of 1,542 patients. Mean age ranged from 49.8 to 83 years and 72% were female. All studies that assessed patient-reported outcome measures before and after surgery reported significant improvements. Complete resolution of paresthesia occurred in 55%-98% of hands across different studies. Resolution of numbness occurred in between 39% and 94% of hands. Pain completely resolved in 64%-100% and weakness in 60%-75% of hands. Two-point discrimination and light touch improved postoperatively. Power grip, key, tripod, index-thumb pulp pinch, and thumb opposition increased. Motor and sensory amplitudes, distal motor latencies, and sensory conduction velocities improved. Patient-reported outcomes indicated symptomatic improvement and reduced disability.

CONCLUSIONS

Symptomatic improvement following carpal tunnel release in patients with severe CTS can occur. Patients should be counseled about the unpredictability of the outcomes and factors that might affect outcomes.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

The rate and associated risk factors for acute carpal tunnel syndrome complicating a fracture of the distal radius

Background

Acute carpal tunnel syndrome (ACTS) is a known complication of distal radius fractures. This study aimed to document the demographics, range of presenting symptoms and risk factors of patients who develop ACTS following a fracture of the distal radius.

Methods

A retrospective review of 1189 patients with an acute distal radius fracture treated in the study centre over a one-year period were identified. Demographic and clinical variables were collected and compared between controls (did not develop ACTS) and those patients who did develop ACTS to identify factors associated with developing ACS.

Results

There were 51 (4.3%) distal radius fractures complicated by ACTS. The mean age of patients who developed ACTS was 56 years (range, 16–89) and 73% were female. The median time of onset post-injury was one week (range, 1–12). There was no association between patient background and comorbidities with the development of ACTS. AO-OTA Type C fractures had significantly increased rates of developing ACTS.

Conclusion

Four percent of distal radius fractures were complicated by ACTS. There was no association between patient background and comorbidities with the development of ACTS. AO-OTA type C complete articular fractures had a significantly higher rate of ACTS. A suggested treatment algorithm for patients presenting with ACTS has been presented.

Level of evidence:

III.

Carpal Tunnel Syndrome and Distal Radius Fractures

Carpal tunnel syndrome (CTS) after distal radius fractures can present in 3 forms: acute, transient, and delayed. Acute CTS requires an emergent carpal tunnel release. Many patients with transient CTS after distal radius fracture do not require surgical release of the carpal tunnel once the fracture is repaired. Prophylactic carpal tunnel release in the absence of signs and symptoms of CTS after a distal radius fracture is not indicated. For patients with delayed CTS after a distal radius fracture, all possible causes of nerve compression should be considered and addressed in standard fashion.

Psychophysical and Patient Factors as Determinants of Pain, Function and Health Status in Shoulder Disorders

Objective:

To estimate the extent to which psychophysical quantitative sensory test (QST) and patient factors (gender, age and comorbidity) predict pain, function and health status in people with shoulder disorders. To determine if there are gender differences for QST measures in current perception threshold (CPT), vibration threshold (VT) and pressure pain (PP) threshold and tolerance.

Design:

A cross-sectional study design.

Setting:

MacHAND Clinical Research Lab at McMaster University.

Subjects:

34 surgical and 10 nonsurgical participants with shoulder pain were recruited.

Method:

Participants completed the following patient reported outcomes: pain (Numeric Pain Rating, Pain Catastrophizing Scale, Shoulder Pain and Disability Index) and health status (Short Form-12). Participants completed QST at 4 standardized locations and then an upper extremity performance-based endurance test (FIT-HaNSA). Pearson r’s were computed to determine the relationships between QST variables and patient factors with either pain, function or health status. Eight regression models were built to analysis QST’s and patient factors separately as predictors of either pain, function or health status. An independent sample t-test was done to evaluate the gender effect on QST.

Results:

Greater PP threshold and PP tolerance was significantly correlated with higher shoulder functional performance on the FIT-HANSA (r =0.31-0.44) and lower self-reported shoulder disability (r = -0.32 to -0.36). Higher comorbidity was consistently correlated (r =0.31-0.46) with more pain, and less function and health status. Older age was correlated to more pain intensity and less function (r =0.31-0.57). In multivariate models, patient factors contributed significantly to pain, function or health status models (r² =0.19-0.36); whereas QST did not. QST was significantly different between males and females [in PP threshold (3.9 vs. 6.2, p < .001) and PP tolerance (7.6 vs. 2.6, p < .001) and CPT (1.6 vs. 2.3, p =.02)].

Conclusion:

Psychophysical dimensions and patient factors (gender, age and comorbidity) affect self-reported and performance-based outcome measures in people with shoulder disorders.

Low myelinated nerve-fibre density may lead to symptoms associated with nerve entrapment in vibration-induced neuropathy

Prolonged exposure to hand-held vibrating tools may cause a hand-arm vibration syndrome (HAVS), sometimes with individual susceptibility. The neurological symptoms seen in HAVS are similar to symptoms seen in patients with carpal tunnel syndrome (CTS) and there is a strong relationship between CTS and the use of vibrating tools. Vibration exposure to the hand is known to induce demyelination of nerve fibres and to reduce the density of myelinated nerve fibres in the nerve trunks. In view of current knowledge regarding the clinical effects of low nerve-fibre density in patients with neuropathies of varying aetiologies, such as diabetes, and that such a low density may lead to nerve entrapment symptoms, a reduction in myelinated nerve fibres may be a key factor behind the symptoms also seen in patients with HAVS and CTS. Furthermore, a reduced nerve-fibre density may result in a changed afferent signal pattern, resulting in turn in alterations in the brain, further prompting the symptoms seen in patients with HAVS and CTS. We conclude that a low nerve-fibre density lead to symptoms associated with nerve entrapment, such as CTS, in some patients with HAVS.

Carpal tunnel syndrome after distal radius fracture

Carpal tunnel syndrome is a common condition and is a well-recognized phenomenon following a distal radius fracture. The treating surgeon should be vigilant in noticing the signs and symptoms. If acute carpal tunnel syndrome is noted, then surgical release of the carpal tunnel and fracture fixation should be performed urgently. If early carpal tunnel syndrome findings are noted during distal radius fracture management, all potential causes should be evaluated. Delayed carpal tunnel syndrome presenting after a distal radius fracture has healed is best managed in standard fashion. There is no role for prophylactic carpal tunnel release at the time of distal radius fixation in a patient who is asymptomatic.

A PROSPECTIVE PLAN TO MINIMISE MEDIAN NERVE RELATED COMPLICATIONS ASSOCIATED WITH OPERATIVELY TREATED DISTAL RADIUS FRACTURES

Loss of median nerve function or a neuropathic pain syndrome may occur in around 20% of distal radius fractures if post-traumatic oedema in the carpal canal generates excessive pressure on the median nerve. No method currently exists to reliably distinguish which patients may benefit from a concomitant carpal tunnel release. This case series details the results of following a prospective plan designed to minimise median nerve related complications associated with distal radius fractures by measuring Semmes-Weinstein monofilament scores in 374 radius fracture patients who underwent surgical stabilisation. One hundred and sixty-nine patients with the clinical symptoms of median nerve compression, a decrement in monofilament score of grade 1 (out of 5) compared to the contralateral side or at least 4.31 g underwent concomitant carpal tunnel release. The remaining 205 patients did not have carpal tunnel release. There were no cases of neuropathic pain or loss of median nerve function.

Functional sensibility assessment. Part II: Effects of sensory improvement on precise pinch force modulation after transverse carpal tunnel release

Patients with median nerve compression at the carpal tunnel often have poor sensory afferents. Without adequate sensory modulation control, these patients frequently exhibit clumsy performance and excessive force output in the affected hand. We analyzed precision grip function after the sensory recovery of patients with carpal tunnel syndrome (CTS) who underwent carpal tunnel release (CTR). Thirteen CTS patients were evaluated using a custom-designed pinch device and conventional sensory tools before and after CTR to measure sensibility, maximum pinch strength, and anticipated pinch force adjustments to movement-induced load fluctuations in a pinch-holding-up activity. Based on these tests, five force-related parameters and sensory measurements were used to determine improvements in pinch performance after sensory recovery. The force ratio between the exerted pinch force and maximum load force of the lifting object was used to determine pinch force coordination and to prove that CTR enabled precision motor output. The magnitude of peak pinch force indicated an economic force output during manipulations following CTR. The peak pinch force, force ratio, and percentage of maximum pinch force also demonstrated a moderate correlation with the Semmes-Weinstein test. Analysis of these tests revealed that improved sensory function helped restore patients' performance in precise pinch force control evaluations. These results suggest that sensory information plays an important role in adjusting balanced force output in dexterous manipulation.

Developing biologically-based assessment tools for physical therapy management of neck pain

SYNOPSIS

Neck pain is a common and episodic condition that is treated using a spectrum of interventions known to be moderately effective but is associated with a significant incidence of chronic pain. Recently, there has been increased focus on defining biological aspects of neck pain. Studies have indicated that neurophysiological, biomechanical, and motor control abnormalities are present and may be useful either in prognosis or classification. We review some of these findings in the context of our own work defining biological markers that may form the basis for clinical tests that can be used for prognosis, classification, or outcome evaluation in patients with neck pain. We have identified abnormalities in neurophysiology using quantitative sensory testing (vibration, touch, and current perception) and response to cold provocation that are related to neck disability. We have identified altered muscle biochemistry by measuring circulating muscle proteins in a lumbar surgery model and are now applying those methods to whiplash injury. We have incorporated capnography into treatment to address central physiological changes present in some patients by monitoring and training CO2 levels. We have developed an innovative new test, the Neck Walk Index, that captures abnormal control of head movement during slow gait as a means of differentiating patients with neck pain from either unaffected controls or individuals with other pathologies. We have used time-varying 3-dimensional joint orientation kinematics to assess deficits in motor control during an upper extremity reach task, the results showing that poor coordination and control of the shoulder girdle leads to shoulder guarding and inconsistencies in elbow joint movement. Despite some promising early results, future research is needed to determine how these measures help clinicians to diagnose, evaluate, and forecast future outcome for patients who present with neck pain.

LEVEL OF EVIDENCE

Diagnosis, level 5.

The impact of wrist extension provocation on current perception thresholds in patients with carpal tunnel syndrome: a pilot study

PURPOSE

To determine whether current perception threshold (CPT) varied between subjects with and without carpal tunnel syndrome (CTS) and whether positioning in wrist extension (reversed Phalen's test) was provocative.

METHOD

Subjects (n=30) were tested using the Neurometer (Neutron, Inc., Baltimore, MD) at 5, 250, and 2,000 Hz in a rest and reverse Phalen's position. Group and positional differences were analyzed using analysis of variance.

RESULTS

Higher CPT occurred at 2,000 Hz in both rest (p=0.02) and reverse Phalen's position (p=0.01) in CTS subjects. There was also a significant change in CPT in the CTS group following wrist extension, particularly at 2,000 Hz (p<0.05).

CONCLUSION

A positional effect on sensibility was noted at 2,000 Hz in subjects with CTS. Further evaluation is required to determine the role and optimal test protocols for provocative-sensory testing in diagnosis and outcome assessment of CTS. For CPT these should focus on using the 2,000 Hz frequency.

On the activation threshold of nerve fibers using sinusoidal electrical stimulation

Carpal tunnel syndrome (CTS) diagnosis could be improved by selectively activating different types of nerve fibers traversing the carpal tunnel based on their diameter. The objective of this study was to establish the types of fibers activated by different sinusoidal electrical stimuli. The frequencies selected correspond to those used in an available application known as current perception threshold (CPT). This method has been proposed in the literature to assess the severity of CTS in a patient. CPT operates by varying the amplitude and frequency of stimulating sine wave currents. Subthreshold and supra-threshold responses of nerve fibers were modeled in this study using McNeal's model and Frankanhaeuser-Huxley equations. Simulations were performed in MATLAB to determine the stimulating thresholds for different diameter groups of nerve fibers. The study concluded that large A-beta fibers can be activated alone at the 2000 Hz frequency, the intermediate A-delta fibers can be activated at the 250 Hz frequency in company of A-beta fiber activity, and for fibers with diameter less than 2.5 mum to be activated at the 5 Hz frequency there must be accompanying activity from A-beta and A-delta fibers.

A correlative electrophysiologic study of nerve fiber involvement in carpal tunnel syndrome using current perception thresholds

OBJECTIVE

To relate clinical severity of idiopathic carpal tunnel syndrome (CTS) to current perception threshold (CPT).

METHODS

Subjects were 51 patients with CTS (involving 51 hands), and 50 healthy control subjects (50 hands). Involved hands were grouped into three clinical grades (mild, moderate, severe). Using a neurometer (Neurotron, Baltimore, MD), we investigated the relationship between clinical grade and CPT abnormalities.

RESULTS

In the mild CTS group, most hands showed CPT abnormalities only at 2000 Hz stimulation. The moderate group included a higher percentage of hands showing abnormalities at both 2000 and 250 Hz stimulation increased. The severe group included the highest percentage of hands with abnormal values at all frequencies tested.

CONCLUSIONS

CPT showed abnormalities appear progressively from 'higher to lower' frequency stimulations relative to the increasing severity of CTS.

SIGNIFICANCE

Sensory nerve fiber dysfunction apparently begins in larger fibers, extending stepwise to smaller fibers as the clinical grade of CTS progresses.