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 in paraplegic patients

Thirty-eight (49 per cent) of seventy-seven paraplegic patients whose level of injury was at or caudad to the second thoracic vertebra were found to have signs and symptoms of carpal tunnel syndrome. The prevalence of carpal tunnel syndrome was found to increase with the length of time after the injury. In the eighteen patients in whom manometric studies were done, the carpal tunnel pressures when the wrist was in the neutral position were higher than those that have been reported in non-paraplegic patients who did not have carpal tunnel syndrome but were lower than the values in non-paraplegic patients who did have the syndrome. When the wrist was in flexion, the pressures were similar to the values that have been reported for non-paraplegic patients. However, in the paraplegic patients, regardless of whether or not they had carpal tunnel syndrome, the pressures that developed when the wrist was in extension were significantly higher than those in non-paraplegic patients, regardless of whether or not they had carpal tunnel syndrome. Most of the activities of daily living of paraplegic patients, including the maneuver to relieve ischial pressure that consists of arising from the seated position using the extended arms, are performed with the wrists locked in maximum extension. The pressure that develops in the carpal canal during this forced extension of the wrist, probably combined with the repetitive trauma to the volar aspect of the extended wrist while propelling a wheelchair, contributes to the high frequency with which carpal tunnel syndrome is found in paraplegic patients.     

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.     

Pressures in the carpal tunnel. A comparison between patients with carpal tunnel syndrome and normal subjects

We studied pressure in the carpal tunnel in patients with carpal tunnel syndrome and in normal control subjects, using a slit catheter and recording in the neutral position, 90 degrees dorsiflexion, and 90 degrees palmarflexion of the wrist. For each position the mean pressure in the patients was very significantly higher than in the controls, the highest pressure being in 90 degrees dorsiflexion, and the lowest in the neutral position. Using an upper limit of normal pressure of 5.5 mmHg in the neutral position gave a diagnostic sensitivity of 78.7%, a specificity of 78.1%, an accuracy of 78.5%, and a positive predictive value of 87.3%.     

Fingertip loading and carpal tunnel pressure: Differences between a pinching and a pressing task

Carpal tunnel syndrome may be caused by repeated or sustained elevated carpal tunnel pressure. This study examined the relationship between carpal tunnel pressure, posture, and fingertip load. In 20 healthy individuals, carpal tunnel pressure was measured with a catheter inserted into the carpal tunnel of the dominant hand and connected to a pressure transducer. With the wrist in a pressure-neutral position, the subjects pressed on a force transducer with the index finger to levels of 0, 5, 10, and 15 N. They then pinched the transducer at the same levels of force. For both fingertip-loading postures, the carpal tunnel pressure increased with increasing fingertip load. Carpal tunnel pressures were significantly greater (p < 0.015) for the pinching task (14.2, 29.9, 41.9, and 49.7 mm Hg [1.89, 3.99, 5.59, and 6.63 kPa] for 0, 5, 10, and 15 N force levels, respectively) than for simple finger pressing (7.8, 14.1, 20.0, and 33.8 mm Hg [1.04, 1.88, 2.67, and 4.51 kPa]). This study indicates that although the external load on the finger remained constant between the two tasks, the internal loading, as measured by carpal tunnel pressure, experienced a near 2-fold increase by using a pinch grip. These findings should be given consideration in designing work tasks and tools because relatively low fingertip forces, especially in a pinch grip, elevate carpal tunnel pressures to levels that, if prolonged, may lead to the development or exacerbation 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.     

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.     

Verification of the pressure provocative test in carpal tunnel syndrome.

Three provocative tests (pressure, Phalen's test, and Tinel's sign) were studied in 30 patients with carpal tunnel syndrome and 30 control subjects. The pressure provocative test had a sensitivity of 100%. In contrast, Phalen's test was 88% sensitive and Tinel's sign only 67% sensitive. The pressure provocative test is a sensitive indicator of median nerve compression at the wrist with a faster reaction time than Phalen's test (mean time of 9 seconds vs 30 seconds). It is an appropriate provocative test in patients with stiff or painful wrists when wrist flexion is restricted.     

Median nerve excursion during endoscopic carpal tunnel release

OBJECTIVE: Restriction of the excursion of the nerve has been accepted as a pathogenetic element in carpal tunnel syndrome. The goal of this article was to evaluate the median nerve excursion in the carpal tunnel measured as a function of wrist position before and after endoscopic carpal tunnel release (ECTR) on 28 hands of 22 patients. METHODS: The position of cylindrical stainless steel markers embedded within the median nerve was measured by a direct radiographic technique. Each upper extremity was examined in three wrist positions. Then, endoscopic release with Menon's technique was performed, and the measurements were repeated. RESULTS: In this prospective clinical study, most (93%) of the patients experienced resolution of their symptoms. Before and after ECTR, median nerve excursion was linear and was affected by wrist position. Before ECTR, when the wrist was moved from the end of dorsiflexion to the end of palmar flexion, the median nerve underwent a mean total excursion of 28.8 mm at the wrist. A comparison of the before and after ECTR excursion showed no statistical differences in the amount of motion. CONCLUSION: The single-portal ECTR does not seem to influence the median nerve excursion for the wrist positions studied in patients with carpal tunnel syndrome. The results from this in vivo study showed longitudinal gliding of the median nerve twice as great as in in vitro studies.     

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.     

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.     

Endoscopic release in carpal tunnel syndrome: analysis of clinical results in 200 cases.

Carpal tunnel syndrome is the most common peripheral neuropathy. Conventional carpal tunnel surgery has been performed as a primary procedure for the decompression of the median nerve at the wrist in patients who have idiopathic carpal tunnel syndrome. While the results have been excellent, this surgical procedure has been reported to be related to high postoperative morbidity and extended length of recovery time. Over the past decade, endoscopic release of the transverse carpal ligament has been developed as a new, alternative method to the open procedures. Endoscopic carpal tunnel release has been reported to ensure less postoperative morbidity, more rapid recovery of strength, with earlier return to work, reduced disability time and a better cosmetic result. The authors present a surgical series of 200 hands in 164 patients (36 bilaterals) with idiopathic carpal tunnel syndrome, who underwent a single-portal endoscopic carpal tunnel release (Agee technique), with regards to the clinical outcome and complications occurred after 4-months follow-up.     

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     

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.     

Acute carpal tunnel syndrome secondary to prolonged pressure on the wrist during enolic coma

We report a case of acute carpal tunnel syndrome caused by prolonged compression. A 40-year-old man was admitted for an acute carpal tunnel syndrome secondary to direct compression of the wrist which was blocked in supination under his thorax for ten hours during a period of alcoholic coma. Total sensorial anesthesia of the median nerve territory was noted. The emergency procedure consisted in simple opening of the carpal tunnel without nerve exploration due to the risk of bacterial contamination resulting from skin lesions, devascularization and postoperative fibrosis. Initially, the skin on the volar aspect of the wrist had the aspect of a second degree burn. The patient recovered nerve function the next day and the skin wound healed within 15 days. The patient was seen at consultation at 13 months and exhibited complete recovery of wrist and hand motion with normal thumb opposition and no signs of sensorial or motor deficit. The retinaculum of the flexor system must be opened to guarantee full nervous recovery.     

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.     

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.     

Compartment pressure in the carpal tunnel in distal fractures of the radius

In a prospective controlled study, carpal tunnel tissue pressures were determined in a group of 56 patients with distal dislocated fractures of the radius at initial presentation, immediately prior to and after reduction, and 1, 2, 4, 12, and 24 h after reduction. Depending on the severity of the trauma and delay to presentation at the hospital, initial measurements revealed raised pressure averaging 23 mmHg, which further increased during reduction to 44 mmHg. After 4 h the average pressure was 37 mmHg, and it then dropped to 26 mmHg after 12 h. For anatomical reasons the median nerve is quite vulnerable in the region of the wrist joint. Chronic pressure here may cause carpal tunnel syndrome. Acute pressure in the carpal tunnel, which according to our investigations represents a distinct compartment, results in an overt compartment syndrome. The possibility of a direct relationship between markedly elevated tunnel pressure and the development of Sudeck's dystrophy is discussed.     

Phalen''s test in the diagnosis of carpal tunnel syndrome

The wrist flexion test of Phalen has been studied in 127 patients with carpal tunnel syndrome and 20 control subjects, all of whom also had nerve conduction studies. There was a statistically significant relationship between the severity of electrical changes and the probability of a positive Phalen's test. However 34% of patients had a negative test and 20% of control subjects a positive one.     

Clinical management of carpal tunnel syndrome in patients with long-term sequelae of poliomyelitis

Thirty-three patients with long-term sequelae of poliomyelitis with a diagnosis of carpal tunnel syndrome established by either abnormal nerve conduction studies or previous carpal tunnel surgery were surveyed. There was no significant long-term resolution of symptoms in the patients who had surgery (n = 9) or were currently using wrist orthoses (n = 11) compared with patients without such treatment (n = 13). In patients who used a single cane or those who used crutches (N = 10), there was a direct correlation between the hand holding the cane or crutch and the hand in which carpal tunnel syndrome developed. The chronic use of cane and crutch predisposes these patients to development of carpal tunnel syndrome, and caution should be used when considering wrist surgery.