Stress carpal tunnel pressures in patients with carpal tunnel syndrome and normal patients

Twenty-two patients with carpal tunnel syndrome scheduled to have a carpal tunnel release, and six volunteer control subjects had carpal tunnel pressures measured with their wrist in neutral position, maximum flexion, and maximum extension. The wrist was then repetitively flexed and extended to maximum position at a rate of 30 full cycles per minute for 1 minute. Pressures were then continually monitored and recorded at 30-second intervals. The pressures were found to be significantly elevated in the immediate post-exercise period in the patients with carpal tunnel syndrome, and they demonstrated a prolonged recovery time to reach the resting pressure when compared with the normal control subjects. This property of prolonged recovery time in patients with carpal tunnel syndrome suggests a possible cause for carpal tunnel syndrome in the occupational setting.     

Measurement of pressure in the carpal canal before and after endoscopic management of carpal tunnel syndrome

In forty-six patients who had carpal tunnel syndrome, a technique of continuous infusion, given under local anesthesia and without a pneumatic tourniquet, was used to measure pressures in the carpal canal before and after endoscopic release of the transverse carpal ligament (retinaculum flexorum manus). Pressures were similarly measured in sixteen subjects in a control group. The mean preoperative pressures were significantly higher in the patients who had carpal tunnel syndrome than in the patients in the control group when the pressures were measured under four conditions: with the wrist in the resting position, with active grip, and with maximum passive extension and flexion of the wrist. The mean pressures improved significantly postoperatively and were in the range of values that were found under each condition for the control group. Measurement of pressure in the carpal canal before and after operation may be useful in diagnosing carpal tunnel syndrome and in determining the effectiveness of endoscopic management.     

Carpal tunnel syndrome secondary to wrist and finger flexor spasticity

Ten patients with spastic wrist flexion deformities secondary to traumatic brain injury were evaluated for carpal tunnel syndrome. The angle of wrist flexion deformity averaged 75 degrees (range, 58 to 115 degrees). Nerve conduction studies demonstrated prolonged median motor and/or sensory latencies in all patients. Preoperative wick catheter measurements of carpal tunnel pressures in eight patients averaged 11 mm Hg in the resting position, 21 mm Hg in maximal wrist flexion, and 15 mm Hg in maximal extension. Each patient had carpal tunnel release with simultaneous wrist and finger flexor tendon releases or lengthenings. At surgery nine of the median nerves were constricted at the proximal edge of the transverse carpal ligament. The presence of normal carpal tunnel pressures and impingement of the median nerve at the proximal edge of the transverse carpal ligament indicates that the chronically flexed posture of the wrist resulted in median nerve compression, and this condition may be aggravated by underlying pressure from the spastic finger flexors.     

Effect of wrist position on power grip and key pinch strength following carpal tunnel decompression

Power grip and thumb key pinch strength were measured pre- and immediately postoperatively in 30 patients with carpal tunnel syndrome while the wrist was in flexion and extension. The carpal tunnel decompression was performed under local infiltration with 1% lignocaine. Grip strength decreased more in wrist flexion than in wrist extension. No difference was found in thumb pinch strength. The authors conclude that some of the immediate postoperative loss of grip strength in wrist flexion can be attributed to prolapse of flexor tendons out of the carpal tunnel in this position.     

Postoperative changes of carpal canal pressure in carpal tunnel syndrome: a prospective study with follow-up of 1 year

Carpal canal pressures were measured in 103 patients with idiopathic carpal tunnel syndrome, before and after open release, with a postoperative follow-up of 1 year. Twenty-five normal subjects were used as controls. Pressures were measured with the wrists in three positions: neutral, full passive flexion and full passive extension. At each wrist position, the mean pre-operative pressures in the study group were significantly higher than in the control group. In both groups, the pressures were maximal with full passive extension and minimal in the neutral wrist position. Immediately after surgical release, there was a marked decrease of the carpal canal pressures. However, during the second postoperative month, there was a significant increase of the pressures at each wrist position, although these were still within the normal control range. This rise in pressures persisted to 12 months. These findings suggest that the carpal ligament reconstitutes by normal scar formation, but with lengthening such that the volume of the carpal canal is enlarged, so preventing a rise in pressure with return of the pre-operative problem.     

The possible role of vascular congestion in carpal tunnel syndrome

A study of interstitial pressures within the carpal tunnel using a slit catheter found that, in some patients, an initial rise in pressure is recorded when the wrist is passively extended and this continues to rise to a plateau if the position is maintained. A rise above a critical pressure brought about by congestion would explain the clinical picture of predominantly nocturnal symptoms and no electro-physiological evidence with the wrist in a neutral (resting) position. The results also bring into doubt published results of the pressure within the carpal tunnel with the wrist flexed or extended, since the pressure can be changed at will, depending on the flexion or extension force used.     

Sensitivity and specificity of clinical testing for carpal tunnel syndrome

OBJECTIVE:

The present study evaluated the sensitivity, specificity and predictive values of six clinical tests in the diagnosis of carpal tunnel syndrome (CTS).

METHODS:

There were 29 carpal tunnel syndrome (CTS) subjects (mean age 48 years) and 30 control subjects (mean age 45 years). The six clinical tests included Tinel’s sign, wrist flexion with fingers extended, wrist flexion with fingers flexed, wrist extension, combined wrist extension/median nerve pressure and combined wrist flexion/median nerve pressure.

RESULTS:

The highest sensitivity and highest negative predictive value was found with wrist flexion with pressure (96%) and wrist extension with pressure (94%) at 60 s. The highest specificity was found with wrist flexion with fingers flexed for 30 s (95%). The highest positive predictive values were found with the wrist flexion with fingers flexed test for 30 s (91%) and the wrist extension test for 30 s (90%).

CONCLUSION:

No one test possesses all the qualities necessary to be the ideal clinical test for the detection of carpal tunnel syndrome.     

Comparison of range-of-motion constraints provided by prefabricated splints used in the treatment of carpal tunnel syndrome: a pilot study.

Nocturnal splinting of the wrist is commonly used to treat carpal tunnel syndrome. Rationales for overnight wrist splinting are based on several research studies, which suggest that passively and actively sustained positions of the wrist and digits during sleep contribute to elevated carpal tunnel pressures. The types of splints used for carpal tunnel syndrome include custom and prefabricated orthoses of many variations. The purpose of this paper is to assess the resting and passive range-of-motion position restrictions and parameters provided by four prefabricated orthoses commonly prescribed for or used by patients at the authors' treatment facility. A literature review provides information that supports optimal wrist and finger positioning to minimize resting carpal tunnel pressures. This information may be useful in determining the most effective splint design choices.     

Canal pressures before,during, and after endoscopic release for idiopathic carpal tunnel syndrome

A special transducer was used to measure in situ carpal tunnel pressures in 20 patients who had surgery for idiopathic carpal tunnel syndrome (CTS) by one-portal endoscopic section of the flexor retinaculum. Pressures were elevated initially. The pressures were maximal (mean, 93 mm Hg) with full passive wrist extension. Peaks of high pressures, on average 97 mm Hg, were recorded with the Agee (MicroAire, Charlottesville, VA) endoscopic device in the canal. Release of the endoscopic flexor retinaculum resulted in a marked decrease of the pressures.     

On Resection of the Knee

In 16 patients, where the diagnosis carpal tunnel syndrome was electrophysiologi-cally confirmed, the pressure between the median nerve and the carpal ligament was measured peroperatively.

At rest the pressure was 18-64 mmHg, mean 31 mmHg. Passive volar and dorsal wrist flexion increased the pressure about three times. Isometric or isotonic maximal contractions of wrist and finger muscles, elicited by tetanic nerve stimulation increased the pressure to three to six times the resting value. These high pressures may be one of the causes of the nerve lesion in the carpal tunnel syndrome.     

Carpal canal pressure of the distracted wrist

PURPOSE: This study was conducted to study the effect of distraction across the wrist joint on carpal canal pressure. METHODS: Ten cadaver specimens were mounted vertically in neutral forearm rotation by 2 half pins that transfixed the radius and ulna. The wrist joint was distracted by suspending weights from the middle finger. A balloon-tipped catheter, percutaneously introduced into the carpal canal and connected to a transducer, was used to measure carpal canal pressure. The carpal canal pressure was measured at 0 to 4.54 kg of distraction in 0.45-kg increments and at 6.81 kg and 9.08 kg of distraction. Three wrist positions were tested: neutral, 30 degrees of flexion, and 30 degrees of extension. RESULTS: Highly linear direct relationships between wrist distraction force and carpal canal pressure over baseline were observed in all positions of the wrist. Statistically significant increases in carpal canal pressure over baseline were observed at a wrist distraction force of 2.27 kg or more with the wrist in neutral position, at 1.82 kg or more with the wrist in 30 degrees of extension, and at 4.09 kg or more with the wrist in 30 degrees of flexion. At each level of wrist distraction force of 3.63 kg or less the carpal canal pressure of the extended wrist was significantly higher than that of the wrist in neutral position. At each level of wrist distraction force 4.54 kg or less the carpal canal pressure of the extended wrist was significantly higher than that of the flexed wrist. No statistically significant differences were observed at any level of wrist distraction force between carpal canal pressures in the neutral and flexed positions of the wrist. CONCLUSIONS: Distraction across the wrist joint causes a statistically significant highly linear increase in carpal canal pressure. The position of the distracted wrist also has a considerable effect on carpal canal pressure, with the extended position associated with the largest increases in carpal canal pressure and the flexed position with the smallest increases in carpal canal pressure.     

Gliding characteristics between flexor tendons and surrounding tissues in the carpal tunnel: a biomechanical cadaver study.

The purpose of this study was to investigate the gliding characteristics of flexor tendons within the carpal tunnel with varied wrist positions and tendon motion styles, which may help us to understand the relationship between carpal tunnel syndrome (CTS) and repetitive hand motion. Eight fresh human cadaveric wrists and hands were used. The peak (PGR) and mean (MGR) gliding resistance of the middle finger flexor digitorum superficialis tendon were measured with the wrist in 0, 30, and 60 degrees of flexion and extension. While moving all three fingers together, the PGR at 60 degrees flexion was significantly higher than that at 0, 30, or 60 degrees extension. While moving the middle finger alone, the PGR at 60 and 30 degrees flexion was significantly higher than the PGR at 60 degrees extension. The PGR moving the middle finger FDS alone was significantly greater than that for all three digits moving together in 0, 30, and 60 degrees flexion. Differential finger motion with wrist flexion elevated the tendon gliding resistance in the carpal tunnel, which may be relevant in considering the possible role of wrist position and activity in the etiology of CTS.     

The clinical significance of the palmaris longus tendon in the pathophysiology of carpal tunnel syndrome

Carpal tunnel syndrome is associated with increased intracarpal canal pressure. The effect of tendon loading on intracarpal canal pressures is documented in biomechanical studies. Palmaris longus loading in wrist extension induces the greatest absolute increase in intracarpal canal pressure. Despite this fact, the palmaris longus is not yet a proven independent risk factor for the development of carpal tunnel syndrome. The purpose of this prospective clinical study was to assess and quantify the association between the presence of a palmaris longus tendon and carpal tunnel syndrome. Thirty-six carpal tunnel subjects with bilateral disease were compared with 36 controls. Each subject was clinically examined for the presence of the palmaris longus tendon. The prevalence of palmaris longus agenesis was significantly lower in the carpal tunnel group. The palmaris longus tendon is a strong independent risk factor for carpal tunnel syndrome.     

Evaluation of Dynamic Carpal Arch Stability following Carpal Tunnel Release Using Four-Dimensional Computed Tomography

Introduction  This study aimed to assess the carpal arch dynamics during active finger and wrist motion following carpal tunnel release using four-dimensional computed tomography (4D-CT). Materials and Methods  Four patients who diagnosed with bilateral carpal tunnel syndrome and underwent unilateral carpal tunnel release were prospectively included. 4D-CT of the bilateral wrists during active finger and wrist motion was performed for 10 seconds at five frames per second. The distances between the tip of tuberosity of the scaphoid and the volar ridge of the pisiform (S–P distance) and volar ridge of trapezium and the tip of hook of hamate (T–H distance) were measured at each position and the values of S–P and T–H distances were compared between the postoperative and contralateral wrists. Results  During finger motion, the S–P and T–H distances were not different at any position between the postoperative side and contralateral side. Conversely, S–P and T–H distances gradually increased in the postoperative wrists. The differences between the sides of S–P distance were significant, with >0 degrees of wrist extension, and differences of T–H distance were significant with >15 degrees of wrist extension. Conclusion  This study demonstrated the carpal arch dynamics using 4D-CT and revealed that the carpal arch was widened with the wrist in extension after carpal tunnel release. This study suggests that the transverse carpal ligament plays an important role in maintaining carpal arch stability.     

The use of ultrasound imaging to demonstrate reduced movement of the median nerve during wrist flexion in patients with non-specific arm pain

Following clinical screening, we examined movement of the median nerve at the wrist using high-resolution (10-22 MHz) ultrasound in 16 controls and 12 patients with non-specific arm pain (also referred to as repetitive strain injury). Imaging was performed just proximal to the carpal tunnel with the wrist in neutral, 30 degrees of extension and 30 degrees of flexion. In control subjects the position of the median nerve was 4.8 (SE=0.4) mm more radial with the wrist flexed than with the wrist extended. In the twelve arm pain patients the average change was only 1.2 (SE=0.5) mm. It appears that ultrasound imaging may be helpful in diagnosing non-specific arm pain, a condition for which there are no well-defined diagnostic tests at present. The reduced nerve movement seen with ultrasound imaging confirms previous work with magnetic resonance imaging.     

Median nerve deformation in differential finger motions: ultrasonographic comparison of carpal tunnel syndrome patients and healthy controls

We investigated the median nerve deformation in the carpal tunnel in patients with carpal tunnel syndrome and controls during thumb, index finger, middle finger, and a four finger motion, using ultrasound. Both wrists of 29 asymptomatic volunteers and 29 patients with idiopathic carpal tunnel syndrome were evaluated by ultrasound. Cross‐sectional images during motion from full extension to flexion were recorded. Median nerve cross‐sectional area, perimeter, aspect ratio of the minimal enclosing rectangle, and circularity in extension and flexion positions were calculated. Additionally, a deformation index was calculated. We also calculated the intra‐rater reliability. In both controls and patients, the median nerve cross‐sectional area became significantly smaller from extension to flexion in all finger motions (p < 0.05). In flexion and extension, regardless of the specific finger motion, the median nerve deformation, circularity and the change in perimeter were all significantly greater in CTS patients than in controls (p < 0.05). We found excellent intra‐rater reliability for all measurements (ICC > 0.84). With this study we have shown that it is possible to assess the deformation of the median nerve in carpal tunnel syndrome with ultrasonography and that there is more deformation of the median nerve in carpal tunnel syndrome patients during active finger motion. These parameters might be useful in the evaluation of kinematics within the carpal tunnel, and in furthering our understanding of the biomechanics of carpal tunnel syndrome in the future. © 2011 Orthopaedic Research Society. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:643–648, 2012     

Carpal tunnel syndrome: a question of hand and wrist configurations?

This study investigated whether there is an association between hand and wrist configurations and the occurrence of carpal tunnel syndrome. The external hand and wrist dimensions of 50 subjects with carpal tunnel syndrome and 50 healthy volunteers were measured and compared. In addition carpal tunnel depth and width were determined with ultrasound. Our results showed that the hand length was significantly higher in the control group (hand length, 19.0; SD, 1.0 cm: patients' hand length, 18.2; SD, 1.1cm) and the palm width was significantly greater in the patients' group (palm width, 9.1; SD, 0.7 cm: controls palm width, 8.6; SD, 0.6 cm). Carpal tunnel syndrome patients had a squarer wrist (wrist ratio, 0.72; SD, 0.1) and carpal tunnel (carpal tunnel ratio, 0.48; SD, 0.1) than the controls (wrist ratio, 0.68; SD, 0.1; carpal tunnel ratio, 0.42; SD, 0.1). These findings indicate that the anatomy of the hand, wrist and carpal tunnel may predispose to carpal tunnel syndrome.     

Effect of wrist posture on carpal tunnel pressure while typing

Long weekly hours of keyboard use may lead to or aggravate carpal tunnel syndrome. The effects of typing on fluid pressure in the carpal tunnel, a possible mediator of carpal tunnel syndrome, are unknown. Twenty healthy subjects participated in a laboratory study to investigate the effects of typing at different wrist postures on carpal tunnel pressure of the right hand. Changes in wrist flexion/extension angle (p = 0.01) and radial/ulnar deviation angle (p = 0.03) independently altered carpal tunnel pressure; wrist deviations in extension or radial deviation were associated with an increase in pressure. The activity of typing independently elevated carpal tunnel pressure (p = 0.001) relative to the static hand held in the same posture. This information can guide the design and use of keyboards and workstations in order to minimize carpal tunnel pressure while typing. The findings may also be useful to clinicians and ergonomists in the management of patients with carpal tunnel syndrome who use a keyboard. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1269–1273, 2008     

Unilateral carpal tunnel syndrome and space-occupying lesions

To assess the association between unilateral carpal tunnel syndrome and space-occupying lesions, 128 patients have been reviewed. They were divided into bilateral, subclinical (unilateral signs and symptoms, and bilateral slowing in the median nerve conduction) and unilateral carpal tunnel syndrome. Space-occupying lesions were investigated on the basis of physical examination and wrist imaging using plain radiographs and ultrasonograms. Of 20 patients with unilateral carpal tunnel syndrome, space-occupying lesions were found in seven (occult ganglion in five and occult calcified mass in two). In contrast, none of 89 patients with bilateral carpal tunnel syndrome and 19 with subclinical carpal tunnel syndrome had space-occupying lesions. We conclude that careful examination and wrist imaging on suspicion of local pathology, especially a space-occupying lesion, are needed when the condition is unilateral and the aetiology is not clear from the history and on physical examination.     

Anatomical relations in the carpal tunnel: a computed tomographic study

Computed tomography of the carpal tunnel was performed in the hands of both patients and controls in a neutral position, in flexion and in extension. The median nerve was not compressed between the long flexors and the flexor retinaculum in either flexion or extension of the wrist. In flexion, the nerve usually moved dorsally, away from the flexor retinaculum. No difference could be found between the cross-sectional area of the carpal tunnel between patients and controls.