Intraoperative assessment of median nerve blood flow during carpal tunnel release with laser Doppler flowmetry

Eleven consecutive median nerves in patients with clinical carpal tunnel syndrome were examined prospectively with laser Doppler flowmetry. All procedures were done without a tourniquet with the patient under local or general anesthesia. Multiple measurements of median nerve blood flow were obtained during carpal tunnel release. Flow characteristics proximal to the transverse carpal ligament did not change after release of the ligament. Beneath the transverse carpal ligament, initial flow was random in 10 of 11 nerves. Within 1 minute after release of the transverse carpal ligament, flow became pulsatile and synchronized with the patient's pulse in nine nerves. Although preliminary, these data suggest that in carpal tunnel syndrome the segment of median nerve beneath the carpal ligament is relatively ischemic and this ischemia may be a factor in the development of symptomatic median nerve entrapment. The rapid return of a pulsatile signal within the nerve after release is positively correlated with relief or improvement of median nerve dysesthesias.     

Complete median nerve transection as a complication of carpal tunnel release with a carpal tunnel tome

A 48 year-old right-hand-dominant man presented to our institution with paresthesia and loss of feeling along the median nerve distribution of the right hand 1 week after undergoing minimally open carpal tunnel release with the Biomet Indiana Tome at another hospital. At surgery, transection of the median nerve was discovered and repaired. This is the first report of a complete median nerve transection using the revised carpal tunnel tome with a single-pass technique.     

Measurement of carpal canal and median nerve pressure in patients with carpal tunnel syndrome

Carpal tunnel syndrome is a compression neuropathy wherein the median nerve is compressed inside of the carpal canal. Its diagnosis is made clinically, electrophysiologically, and sometimes by carpal canal pressure measurement. The objective of surgical management of this condition is the decompression of the median nerve. We usually measure carpal canal pressure preoperatively and postoperatively using a continuous infusion technique for diagnoses as well as for postoperative evaluation of decompression following our Universal Subcutaneous Endoscope system procedure. To evaluate whether our procedure effectively decompressed the median nerve, we measured intraneural pressure preoperatively and postoperatively in the resting position, with active power grip, and in the Okutsu test position. Correlation between the carpal canal pressure and intraneural median nerve pressure was statistically analyzed using the Kendall rank correlation coefficient (n = 157 hands). A significant correlation was present preoperatively in resting position and postoperatively with active power grip and in the Okutsu test position. Because of this correlation, we conclude that our endoscopic operative procedure effectively decompresses the median nerve and that simple carpal canal pressure measurement is sufficient to confirm diagnoses and to evaluate the status of postoperative decompression.     

Tendon blood flow assessed by laser Doppler flowmetry.

Laser Doppler flowmetry was applied to the surface of both achilles tendons in 10 mature albino rats. A prompt decline in flux values by about 60% was noted when the blood supply to the limb was interrupted by clamping the femoral artery. Increased values, indicating a hyperaemic reaction, often followed release of the clamp. Flux values reached a minimum after death, and this was used as a baseline measurement to eliminate Doppler signals generated by factors unrelated to flow. Although readings in two animals had to be omitted for technical reasons, the present study shows that reliable laser Doppler flow readings can be obtained from the surface of a tendon. The response to reversible ischaemia is prompt and reproducible. Laser Doppler flowmetry may offer a new approach to the assessment of tendon blood flow at the microvascular level.     

Measurement of blood flow in the rotator cuff using laser Doppler flowmetry

The aim of this study was to define the microcirculation of the normal rotator cuff during arthroscopic surgery and investigate whether it is altered in diseased cuff tissue. Blood flow was measured intra-operatively by laser Doppler flowmetry. We investigated six different zones of each rotator cuff during the arthroscopic examination of 56 consecutive patients undergoing investigation for impingement, cuff tears or instability; there were 336 measurements overall. The mean laser Doppler flowmetry flux was significantly higher at the edges of the tear in torn cuffs (43.1, 95% confidence interval (CI) 37.8 to 48.4) compared with normal cuffs (32.8, 95% CI 27.4 to 38.1; p = 0.0089). It was significantly lower across all anatomical locations in cuffs with impingement (25.4, 95% CI 22.4 to 28.5) compared with normal cuffs (p = 0.0196), and significantly lower in cuffs with impingement compared with torn cuffs (p < 0.0001). Laser Doppler flowmetry analysis of the rotator cuff blood supply indicated a significant difference between the vascularity of the normal and the pathological rotator cuff. We were unable to demonstrate a functional hypoperfusion area or so-called 'critical zone' in the normal cuff. The measured flux decreases with advancing impingement, but there is a substantial increase at the edges of rotator cuff tears. This might reflect an attempt at repair.     

Time course and predictors of median nerve conduction after carpal tunnel release

PURPOSE: To identify predictors of outcome and of electrophysiologic recovery in patients with carpal tunnel syndrome (CTS) treated by endoscopic carpal tunnel release using a nerve conduction testing system (NC-Stat; NEUROMetrix, Inc, Waltham, MA). METHODS: Validity of the automated nerve conduction testing system was shown by comparing presurgical distal motor latencies (DMLs) against a reference obtained by referral to an electromyography laboratory. The DML was evaluated in 48 patients with CTS. Measurements were obtained within 1 hour of surgery and at 2 weeks, 6 weeks, 3 months, and 6 months after carpal tunnel release. Presurgical and postsurgical DMLs were then compared and correlated with variables and possible predictors of outcome including age, body mass index, gender, and presurgical DMLs. RESULTS: The automated nerve conduction testing system DMLs matched those of reference electromyography/nerve conduction study values with high correlation. Sensitivity of the automated nerve conduction testing system when compared with a standardized CTS case definition was 89%, with a specificity of 95%. A significant correlation was found between the DML before release and the DML 1 hour after release. Moreover, maximal postsurgical DML improvement was highly dependent on the presurgical DML, with no improvement shown for the <4-ms group, mild improvement for the 4-to-6-ms group, and maximal improvement in the >6-ms group. Among the clinical variables of age, gender, and body mass index only age was mildly predictive of postrelease DML changes at 6 months. No other correlations between clinical variables and postsurgical DMLs were significant. In addition the predictive value of age was lost when combined with the presurgical DML in a multivariate analysis. CONCLUSIONS: Postsurgical changes in the median nerve DML were highly dependent on the prerelease latency. The sensitivity and specificity of a nerve conduction monitoring system in detecting and aiding in the diagnosis of CTS is useful in the long-term management of patients with CTS and can aid in determining the level of improvement in median nerve function after endoscopic carpal tunnel release.     

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.     

Intraoperative electroneurography during median nerve decompression in carpal tunnel syndrome

Summary In 17 patients with the diagnosis of carpal tunnel syndrome, orthodromic sensory nerve conduction measurements during ligament division and internal neurolysis were performed without the use of a pneumatic tourniquet. While ligament division led to an increase in conduction velocity (p < 0.05; median increase 0.7 m/s), it did not result in a significant change of the amplitude. During internal neurolysis, an increase of the sensory nerve potential (p<0.01; median increase 0.9 V) and no significant change in conduction velocity were observed. We conclude that internal neurolysis does not cause a disruption of nerve function during the operation.     

Ultrasound assessment of the effectiveness of carpal tunnel release on median nerve deformation

To assess the biomechanical effect of carpal tunnel release (CTR), we evaluated the deformation and displacement patterns of the median nerve before and after CTR in carpal tunnel syndrome (CTS) patients. Sixteen wrists of 14 idiopathic CTS patients who had open CTR and 26 wrists of 13 asymptomatic volunteers were evaluated by ultrasound. Cross‐sectional images of the carpal tunnel during motion from full finger extension to flexion were recorded. The area, perimeter, aspect ratio of a minimum enclosing rectangle, and circularity of the median nerve were measured in finger extension and flexion positions. Deformation indices, determined by the flexion–extension ratio for each parameter, were compared before and after CTR. After CTR, the deformation indices of perimeter and circularity became significantly larger and the aspect ratio became significantly smaller than those before CTR (p < 0.05). Those differences were more obvious when comparing the values between the patients before CTR and the controls. Since the deformation indices after CTR are similar to the patterns of normal subjects, the surrounding structures and environment of the median nerve may be normalized upon CTR. This may be a way to tell how the median nerves recover after CTR. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:726–730, 2015.     

Peri- and postoperative pain valutation in carpal tunnel release of median nerve compression

We analysed 108 patients, operated on day surgery, for carpal tunnel release of median nerve compression, to evaluate peri- and postoperative pain. We made in all cases a short intertenarian incision (25 mm) with microsurgical technique and local anaesthesia using mepivacaine 2% without vasoconstrictor. We evaluated pain for local anaesthetic infiltration as VRS (Verbal Rating Scale) 6,3 median-time to the first possible analgesic assumption (in all cases paracetamol 500 mg), total analgesic assumption, pressure algometry (to evaluate "allodiny") after the first 48 hours and subjective pain intensity by a numerical pain scale. Pain intensity on first drug assumption (after a mean time of 7 hours from the end of surgery) had a mean VAS value of 2,15; while after a second assumption of analgesic (after a mean time of 15 hours from surgery) had a mean VAS value of 2. Mean total analgesic assumption was 1,64 tablets of paracetamol 500 mg. From these data we may deduce that peri- and postoperative pain following median nerve decompression with this technique and anaesthesia, has a moderate intense peak of brief duration, for local anaesthetic infiltration (that seems to be the most painful event) and modest and not constant pain in the postoperative time (more evident 7 and 15 hours from the end of surgery). It may be useful association with mepivacaine bicarbonate solutions or injecting less painful local anaesthetic.     

Surgical release of the median nerve under local anaesthesia for carpal tunnel syndrome

Carpal tunnel release was performed under local anaesthesia in 124 wrists of 108 patients. The local anesthetic was injected into the carpal tunnel and into the subcutaneous tissue under the line of the skin incision. A tourniquet was used in all cases. Analgesia was complete in all but six patients. Only one patient had real difficulty in tolerating the tourniquet. In 18 cases the median nerve, when exposed at operation, showed evidence of some damage caused by the needle or by injection of local anaesthetic but, at follow-up, no symptoms or signs related to this damage were found.     

Acetabular blood flow during Bernese periacetabular osteotomy: an intraoperative study using laser Doppler flowmetry.

BACKGROUND: The blood flow to the acetabular fragment is of some concern in juxtaarticular pelvic osteotomies used for the treatment of hip dysplasia. No direct measurements have determined the effect of the Bernese periacetabular osteotomy (PAO) on acetabular perfusion. METHODS: Acetabular perfusion was measured by means of laser Doppler flowmetry in 10 patients undergoing a PAO for symptomatic acetabular dysplasia. During the surgical procedure, the intraosseous high energy laser Doppler reliably depicts dynamic changes of small vessel blood flow. Measurements were performed after defined surgical steps to obtain sequential information on the blood perfusion of the acetabular fragment. RESULTS: After complete separation of the acetabular fragment, nine out of 10 patients had pulsatile signals, but the blood flow (BF) significantly decreased by 77%. Corrective positioning of the fragment induced no further drop of the BF signal but a loss of pulsatility in six patients. After a recovery period of about 30 min following preliminary fixation of the fragment, reestablishment of the pulsatile signal and an increase of the BF signal was seen. At termination of the surgical procedure, five out of eight patients, who could be followed throughout the whole procedure, showed a clear pulsatile signal in the supraacetabular area. Bleeding of the supraacetabular cancellous surface could be observed in all acetabula. CONCLUSION: Despite careful preservation of soft tissues during the surgical procedure, a significant reduction of the blood flow in the supraacetabular region has been observed. Nevertheless, a pulsatile signal in more than 60% of the fragments after fragment correction and an increasing signal during the recovery period showed ongoing blood perfusion indicating reversible changes in the measured supraacetabular area. All osteotomies healed within eight weeks without showing signs of necrosis during a minimum follow up of 1 year.     

Giant median nerve in bilateral carpal tunnel syndrome

We introduce a middle age healthy man with sequential bilateral carpal tunnel syndrome. At the surgery, we encountered a wide median nerve in both wrists. Although enlargement of median nerve in carpal tunnel has been well documented, 25 mm width of the nerve is a rare scene, underscoring that leaving the nerve under the unyielding pressure would lead to a fibrous atrophic median nerve.KEY WORDS: Blood-nerve barrier, carpal tunnel syndrome, compressive neuropathy, median nerve, neural edema     

Intraneural median nerve pressure in carpal tunnel syndrome

In order to determine whether endoscopic carpal tunnel release decompresses the median nerve, we measured the intraneural median nerve pressure pre- and postoperatively in 55 hands. The median nerve pressure was significantly reduced postoperatively.     

Ulnar subluxation of the median nerve following carpal tunnel release: a case report

Complications of carpal tunnel release, while infrequent, include incomplete release resulting in persistent symptoms or recurrence due to postoperative scarring, as well as iatrogenic damage to nerves and vessels. We present the case of a patient who underwent carpal tunnel release with resolution of symptoms in the immediate postoperative period. At one and a half years post release he started to experience numbness and tingling in a median nerve distribution triggered by repetitive ulnar to radial deviation of the wrist, with no symptoms at rest. Dynamic ultrasound showed a subluxation of the median nerve from one side of the palmaris longus tendon to the other. The patient's symptoms were triggered as the median nerve squeezed in between the palmaris longus and flexor digitorum superficialis tendons.     

腕管综合征内窥镜手术预防正中神经损伤的临床研究

目的 介绍腕管综合征内窥镜手术(endoscopic carpal tunnel release,ECTR)预防正中神经损伤并发症的方法.方法 利用彩色多普勒超声仪(B超)对37例74手患者术前进行检测.结果 71例正中神经走行在桡侧腕屈肌腱与掌长肌腱之间,3例走行在掌长肌腱与尺侧腕屈肌腱之间,并术中确认.结论 正中神经变异走行在掌长肌腱与尺侧腕屈肌腱之间是ECTR的禁忌证,B超能准确定位正中神经与掌长肌腱关系,避免内窥镜手术损伤正中神经,更具有简单、经济、方便可靠等优点.

Abstract：

Objective To introduce a method of preventing median never injury during endoscopic carpal tunnel release (ECTR). Methods Ultrasonography of both wrists was done to 37 patients of carpal tunnel syndrome who were going to undergo open release of the transverse carpal ligament. Structures in the carpal tunnel were visualized to guide surgical decision-making. Results Ultrasonography showed that median never lies between the tendon of flexor carpi radialis and palmaris longus in 71 patients and lies between the tendon of palmaris longus and flexor carpi ulnaris in 3 patients. These findings were confirmed during the surgeries. Conclusion It is a contraindication of ECTR if median never lies between palmaris longus and flexor carpi ulnaris. Ultrasonography can accurately reveal the relative position of median never to the palmaris longus tendon. Pre-operative ultrasonography of the wrist is a simple, inexpensive and convenient method to exclude these contraindications and thus prevent median never injuries in ECTR.     

A reliable technique for avoiding the median nerve during carpal tunnel injections

Carpal tunnel injections are widely performed for diagnostic and therapeutic purposes. Injury to the median nerve is a serious and fairly common complication. There is no consensus regarding the safest injection site. The objective of this study was to determine the safest injection site based on anatomical data. During 124 endoscopic procedures for median nerve release at the carpal tunnel, we measured the distances separating the median nerve, palmaris longus (PL), flexor carpi radialis (FCR), and flexor carpi ulnaris 1 cm proximal to the wrist crease. The edge of the median nerve extended medially beyond the PL tendon in 82 (88%) hands. Thus, needle insertion within 1 cm of either edge of the PL tendon may cause median nerve injury; with injection sites located further toward the medial edge, the ulnar pedicle may be at risk. Consequently, we recommend that carpal tunnel injections be performed through the FCR tendon.     

Assessment of blood flow through the lung using laser Doppler flowmetry

The value of laser Doppler flowmetry in measuring blood flow through the lung was assessed comparing it with flow measured by electromagnetic flowmetry. This was an experimental laboratory-based prospective study performed in an approved University animal research facility. Ten beagle dogs were used. Simultaneous measurement of pulmonary blood flow by laser Doppler flowmetry and electromagnetic flowmetry was carried out at varying degrees of pulmonary artery constriction. There was a linear relationship between the two methods of assessing blood flow (regression equation: y = 0.9x + 5.5; p = .00001) using a least-squares, best fit, straight line analysis (160 data points). The results of this study demonstrate that laser Doppler flowmetry provides an accurate indicator of pulmonary blood flow, which in practice is both simple and reproducible.