Distribution of nerve endings in human thumb interphalangeal joint.

This study aims to quantitatively analyze the distribution of encapsulated nerve endings in the human thumb interphalangeal (IP) joint capsule. There are three types of nerve endings. Type-I nerve endings (Ruffini-like ending) sense pressure changes, Type II (Pacini-like ending) nerve endings contribute to the kinesthetic sense, and Type III (Golgi-like ending) nerve ending provides proprioceptive information. We dissected five right thumbs IP joints from freshly frozen cadavers (5 men). The mean age of the cadavers at the time of death was 63.4 years (55-73). Sections were stained with the hematoxylin-eosin and antiprotein gene product 9.5 (PGP9.5) to identify encapsulated nerve endings. Transverse sections were cut and divided into volar, dorsal, and then into two equal parts, proximal and distal. The density of encapsulated nerve endings compared to volar versus dorsal and proximal versus distal regions was examined. This study showed that type 1 nerve endings were more common in the distal parts of the IP joint (p < 0.05). Also, type 3 nerve endings were observed in the thumb IP joint. There was no difference between regions in type II and type III nerve endings. The current study demonstrates that the distribution of encapsulated nerve endings in the IP joint is different from the PIP and DIP joints. Moreover, further studies are required to understand the thumb's physiology.

Small Joint Denervation of the Hand and Thumb Base: History, Anatomy, Technique, and Outcomes.

Painful arthritis of the small joints of the hand is a common condition affecting older adults, with distal interphalangeal joint and thumb carpometacarpal joint being the two most common locations. Younger adults may also develop painful arthritis after trauma and with inflammatory arthropathy. Traditional surgical approaches address the structure of the joints with either arthrodesis or arthroplasty with or without an implant. In recent decades, denervation has been reported as an alternative treatment for painful small joints that are mobile and stable. Publications on denervation often report faster surgery and recovery times than traditional surgeries that manipulate the small joint bony structures. This article reviews the history, anatomy, surgical techniques, and outcomes of denervation of the small joints of the hand.

Base of the Third Metacarpal as a Palpable and Reliable Landmark for Identifying the Median Nerve's Thenar Branch.

PURPOSE: The objective of this study was to investigate whether the base of the third metacarpal can predict the location of the thenar branch (TB) of the median nerve and the accuracy of palpating the base of the third metacarpal. METHODS: In 15 patients with ulnar nerve lesions around the elbow, we transferred the opponens motor branch to repair the deep terminal division of the ulnar nerve (DTDUN). Before surgery, we located the TB by palpating the base of the third metacarpal volarly. During surgery, we placed three needles at the following places: one at the entrance of the TB into the abductor pollicis brevis, another at the point where the TB contacted the thenar muscles, and third at the DTDUN's trajectory over the third metacarpal. We obtained fluoroscopic images and measured distances between the needles and structures with image software. We also examined the relationship between the TB, DTDUN, and the volar tubercle of the base of the third metacarpal in cadaver hands. Finally, we invited 22 surgeons to palpate the base of the third metacarpal on volunteer hands and verified their accuracy using fluoroscopy. RESULTS: During surgery, after dissection and palpation of the TB, under fluoroscopy, we confirmed that the palpable bone prominence was the base of the third metacarpal. In cadaver dissections, we observed the TB crossing the volar tubercle of the base of the third metacarpal superficially from proximal to distal and from ulnar to radial. The DTDUN was, on average, 14 mm distal to the base of the third metacarpal distal limit. In total, 19 of the 22 surgeons correctly identified the base of the third metacarpal and consequently the trajectory of the TB. CONCLUSIONS: The palpable base of the third metacarpal can be used to determine the trajectory of both the TB and DTDUN. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.

Effect of a Novel Perturbation-Based Pinch Task Training on Sensorimotor Performance of Upper Extremity for Patients With Chronic Stroke: A Pilot Randomized Controlled Trial.

OBJECTIVE: To investigate the effects of perturbation-based pinch task training on the sensorimotor performance of the upper extremities of patients with chronic stroke via a novel vibrotactile therapy system. DESIGN: A single-blinded randomized controlled trial. SETTING: A university hospital. PARTICIPANTS: Patients with chronic stroke (N=19) randomly assigned into either an experimental group or a control group completed the study. INTERVENTIONS: In addition to 10 minutes of traditional sensorimotor facilitation, each participant in the experimental group received 20 minutes of perturbation-based pinch task training in each treatment session, and the controls received 20 minutes of task-specific motor training twice a week for 6 weeks. MAIN OUTCOME MEASURES: The scores for the primary outcome, Semmes-Weinstein monofilament (SWM), and those for the secondary outcomes, Fugl-Meyer Assessment (FMA), amount of use, quality of movement (QOM) on the Motor Activity Log (MAL) scale, and box and block test (BBT), were recorded. All outcome measures were recorded at pretreatment, post treatment, and 12-week follow-up. RESULTS: There were statistically significant between-group differences in the training-induced improvements revealed in the SWM results (P=.04) immediately after training and in the BBT results (P=.05) at the 12-week follow-up. The changes in muscle tone and in the QOM, SWM, and BBT scores indicated statistically significant improvements after 12 sessions of treatment for the experimental group. For the control group, a significant statistical improvement was found in the wrist (P<.001) and coordination (P=.01) component of the FMA score. CONCLUSIONS: This study indicated that the perturbation-based pinch task training has beneficial effects on sensory restoration of the affected thumb in patients with chronic stroke.

Pediatric Trigger Thumb with Metacarpophalangeal Joint Hyperextension or Instability.

BACKGROUND The aim of this study was to provide the first on report on the mechanism and the different treatment measures of metacarpophalangeal joint hyperextension (MCPH) or metacarpophalangeal joint instability (MCPI) in cases of pediatric trigger thumb. Some pediatric trigger thumb patients have disease combined with excessive extension of metacarpophalangeal (MCP) joint or instability of MCP joint. MATERIAL AND METHODS A total of 1083 children with trigger thumb surgery were divided into 2 groups (the MCPH group and the MCPI group) by the extension degree of the MCP joint. After tendon sheath released, the MCPH group was treated by a cast and the MCPI group was treated by a cast and a brace. We compared the differences in baseline data and the further functional activities of interphalangeal (IP) and MCP joint between the 2 groups. RESULTS Among the 1083 cases, 154 cases (185 thumbs) were trigger thumb with MCPH or MCPI, of which 167 thumbs were placed in the MCPH group and 18 thumbs were placed in the MCPI group. The average age of the MCPH group was 2.8 years, with an average duration of disease of 13 months. The average age of the MCPI group was 6.6 years, with an average duration of disease of 33 months. MCPH still existed after cast removal. In the MCPI group, 12 out of 18 thumbs recovered; 6 thumbs relapsed at 2-4 months after brace removal. CONCLUSIONS Trigger thumb with MCPH and MCPI in children is significantly associated with multi-joint laxity. While there was still MCPH after cast treatment, there was no need for further treatment during the short-term follow-up. Cast and brace treatment after surgery was a simple, easy method for treatment of MCPI and had a good effect.

Selective Thumb Carpometacarpal Joint Denervation for Painful Arthritis: Clinical Outcomes and Cadaveric Study.

PURPOSE: To determine the innervation pattern to the thumb carpometacarpal (CMC) joint and assess the safety and efficacy of selective joint denervation for the treatment of pain and impairment associated with thumb CMC arthritis. METHODS: Cadaveric dissections were performed in 10 fresh upper extremities to better define the innervation patterns to the CMC joint and guide the surgical approach for CMC joint denervation. Histologic confirmation of candidate nerves was performed with hematoxylin and eosin staining. Results from a series of 12 patients with symptomatic thumb CMC arthritis who underwent selective denervation were retrospectively evaluated to determine the safety and efficacy of this treatment approach. Differences in preoperative and postoperative measurements of grip and key-pinch strength as well as subjective reporting of symptoms were compared. RESULTS: Nerve branches to the thumb CMC joint were found to arise from the lateral antebrachial cutaneous nerve (10 of 10 specimens), the palmar cutaneous branch of the median nerve (7 of 10 specimens), and the radial sensory nerve (4 of 10 specimens). With an average follow-up time of 15 months, 11 of 12 patients (92%) reported complete or near-complete relief of pain. Average improvements in grip and lateral key-pinch strength were 4.1 ± 3.0 kg (18% ± 12% from baseline) and 1.7 ± 0.5 kg (37% ± 11% from baseline), respectively. One patient experienced the onset of new pain consistent with a neuroma that resolved with steroid injection. All patients were released to light activity at 1 week after surgery, and all activity restrictions were lifted by 6 weeks after surgery. CONCLUSIONS: Selective denervation of the CMC joint is an effective approach to treat pain and alleviate impairment associated with CMC arthritis. The procedure is well tolerated, with faster recovery as compared with trapeziectomy. Branches arising from the lateral antebrachial cutaneous nerve, palmar cutaneous branch of the median nerve, and radial sensory nerve can be identified and resected with a single-incision Wagner approach. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic V.

Effect of sleep restriction on somatosensory sensitivity in the oro-facial area: An experimental controlled study.

BACKGROUND: No studies have addressed the effect of SR on somatosensory function in the oro-facial area. OBJECTIVES: The aim of this study was to investigate the effect of sleep restriction (SR) on the somatosensory perception of the tip of the tongue. MATERIALS AND METHODS: Using a crossover study design, 13 healthy participants took part in a random order, to a two arms experiments: the SR and control/no SR-arms. For all participants, the Epworth Sleepiness Scale (ESS) was used to assess sleepiness and mechanical sensitivity, and pain detection threshold was estimated at the tongue tip and right thumb (as a body area control site). In the SR-arm of the study, on day one, we estimated sensory baseline perception and repeated tests on day two, after a night of voluntary SR, and on day 3, after a recovery night. In the second arm, same sensory tests were done but no SR was requested. RESULTS: Significantly more sleepiness was observed after SR in comparison with baseline and recovery testing days (P < 0.05). After SR, mechanical pain threshold on the tip of the tongue was significantly lower on day after SR (day 2) and a rebound, higher values, were observed on the third day (P < 0.05); no difference on thumb site. In the control arm, no SR and no significant differences between days were observed for all the variables of interest. CONCLUSIONS: The present results suggest that SR may affect somatosensory perception in the oro-facial area.

The sag response in human muscle contraction.

PURPOSE: We examined how muscle length and time between stimuli (inter-pulse interval, IPI) influence declines in force (sag) seen during unfused tetani in the human adductor pollicis muscle. METHODS: A series of 16-pulse contractions were evoked with IPIs between 1 × and 5 × the twitch time to peak tension (TPT) at large (long muscle length) and small (short muscle length) thumb adduction angles. Unfused tetani were mathematically deconstructed into a series of overlapping twitch contractions to examine why sag exhibits length- and IPI-dependencies. RESULTS: Across all IPIs tested, sag was 62% greater at short than long muscle length, and sag increased as IPI was increased at both muscle lengths. Force attributable to the second stimulus increased as IPI was decreased. Twitch force declined from maximal values across all IPI tested, with the greatest reductions seen at short muscle length and long IPI. At IPI below 2 × TPT, the twitch with highest force occurred earlier than the peak force of the corresponding unfused tetani. Contraction-induced declines in twitch duration (TPT + half relaxation time) were only observed at IPI longer than 1.75 × TPT, and were unaffected by muscle length. CONCLUSIONS: Sag is an intrinsic feature of healthy human adductor pollicis muscle. The length-dependence of sag is related to greater diminution of twitch force at short relative to long muscle length. The dependence of sag on IPI is related to IPI-dependent changes in twitch duration and twitch force, and the timing of peak twitch force relative to the peak force of the associated unfused tetanus.

Transfer of the Motor Branch of the Abductor Digiti Quinti for Thenar Muscle Reinnervation in High Median Nerve Injuries.

PURPOSE: In high median nerve repairs, thenar muscle reinnervation is impossible because of the long distances over which axons must regenerate. To overcome this obstacle, we propose transferring the abductor digiti quinti motor branch (ADQMB) to the thenar branch of the median nerve (TBMN). METHODS: We used 10 embalmed hands for anatomical and histological studies. Thereafter, 5 patients with a high median nerve injury underwent surgical reconstruction within 8 months of their accident and were followed for at least 10 months after surgery (mean, 13.2 months). We transferred the ADQMB to the TBMN. The median nerve was grafted in 4 patients and the motor branch of the extensor carpi radialis brevis was transferred to the anterior interosseous nerve in 3. Patients had pre- and postoperative evaluations of thumb range of motion and strength. RESULTS: In cadaveric hands, the ADQMB was the first branch of the ulnar nerve to arise near the pisiform bone. The TBMN arose from the anterior surface of the median nerve, underneath the flexor retinaculum. Retrograde dissection of the TBMN allowed tension-free coaptation with the ADQMB. Both branches contained approximately 650 myelinated fibers. After surgery, all our patients improved thumb pronation, thenar eminence bulk, and abductor pollicis brevis British Medical Research Council score. They recovered approximately 75% of their normal-side grasp and pinch strength. No patient lost little finger abduction. CONCLUSIONS: Transfer of the ADQMB to the TBMN reinnervated the thenar muscles, which improved thumb range of motion and strength. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic V.

Tree of Vater-Pacinian corpuscles in the human finger and thumb: a comparison between the late fetal stage and old age.

Using histological sections of 12 hands from 12 human fetuses at 20-34 weeks of gestation (150-290 mm) and 14 fingers (index and small) from seven donated cadavers of elderly individuals (aged 78-95 years), we compared the features of Vater-Pacinian corpuscles between these two stages of life. Corpuscles with thin, tightly packed lamellae appeared to undergo a change to thick, loosely packed lamellae at 23-32 weeks. The typical fetal corpuscle had two parts: (1) a rod-like proximal part (0.2-0.6 mm in length) extending along the proximodistal axis of the finger, and (2) a distal end (0.1 mm) after acute bending of the proximal part. Corpuscles were associated with palmar digital nerves in the fingers, but were also present along the dorsal nerves in the thumb. A flower bouquet- or tree-like arrangement including 5-10 corpuscles extended to the dermis of the skin along a perforating artery. Serial sections of the thumb and fifth finger revealed approximately 80-180 corpuscles in the distal phalangeal segment. In elderly individuals, the corpuscles were distributed along the palmar digital nerve, but (1) their density was much lower than in fetuses and (2) a bouquet- or tree-like arrangement was rarely seen. In the distal segment, there were fewer than 40 adult corpuscles, being 0.2-0.5 mm thick and 1.0-2.5 mm long. Wavy or coiled corpuscles were evident. Because of the considerable differences in the distribution and number of corpuscles between the fetus and adult, they appear to undergo considerable depletion with age, especially along thin, superficial nerve branches.

Temporal and Spatial Variability of Surface Motor Activation Zones in Hemiplegic Patients During Functional Electrical Stimulation Therapy Sessions.

The goal of this study was to investigate surface motor activation zones and their temporal variability using an advanced multi-pad functional electrical stimulation system. With this system motor responses are elicited through concurrent activation of electrode matrix pads collectively termed "virtual electrodes" (VEs) with appropriate stimulation parameters. We observed VEs used to produce selective wrist, finger, and thumb extension movements in 20 therapy sessions of 12 hemiplegic stroke patients. The VEs which produce these three selective movements were created manually on the ergonomic multi-pad electrode by experienced clinicians based on visual inspection of the muscle responses. Individual results indicated that changes in VE configuration were required each session for all patients and that overlap in joint movements was evident between some VEs. However, by analyzing group data, we defined the probability distribution over the electrode surface for the three VEs of interest. Furthermore, through Bayesian logic we obtained preferred stimulation zones that are in accordance with our previously reported heuristically obtained results. We have also analyzed the number of active pads and stimulation amplitudes for these three VEs. Presented results provide a basis for an automated electrode calibration algorithm built on a priori knowledge or the starting point for manual selection of stimulation points.

Adaptations of motor neural structures' activity to lapses in attention.

Sustained attention is fundamental for cognition and when impaired, impacts negatively on important contemporary living skills. Degradation in sustained attention is characterized by the time-on-task (TOT) effect, which manifests as a gradual increase in reaction time (RT). The TOT effect is accompanied by changes in relative brain activity patterns in attention-related areas, most noticeably in the prefrontal cortex (PFC) and the right parietal areas. However, activity changes in task-relevant motor structures have not been confirmed to date. This article describes an investigation of such motor-related activity changes as measured with 1) the time course of corticospinal excitability (CSE) through single-pulse transcranial magnetic stimulation; and 2) the changes in activity of premotor (PMC), primary motor (M1), PFC, and right parietal areas by means of near-infrared spectroscopy, during a sustained attention RT task exhibiting the TOT effect. Our results corroborate established findings such as a significant increase (P < 0.05) in lateral prefrontal and right parietal areas activity after the emergence of the TOT effect but also reveal adaptations in the form of motor activity changes--in particular, a significant increase in CSE (P < 0.01) and in primary motor area (M1) activity (P < 0.05).

Bowler's thumb: ultrasound diagnosis of a neuroma of the ulnar digital nerve of the thumb.

Bowler's thumb is a rare traumatic neuropathy of the ulnar digital nerve of the thumb. We present a case of bowler's thumb in a 21-year-old male recreational bowler who presented with a painful mass on the ulnar side of the right thumb. Magnetic resonance (MR) imaging of the hand was inconclusive. However, subsequent ultrasound (US) showed asymmetric enlargement of the ulnar digital nerve of the thumb with marked epineural thickening corresponding to the palpable mass, confirming the clinical diagnosis of bowler's thumb. Although this condition is typically diagnosed clinically, imaging can help to clarify clinical findings. In our experience, MR imaging is a clinician's preferred choice when further evaluating physical findings of digital nerve pathology despite the lack of evidence to support MR as a primary imaging modality for these patients. This case illustrates the role that US can play as an initial imaging modality for the evaluation of small peripheral nerves.

Nerve and Free Gracilis Muscle Transfers for Thumb and Finger Extension Reconstruction in Long-standing Tetraplegia.

PURPOSE: With spinal cord injuries, muscles below the level of the lesion remain innervated despite the absence of volitional control. This persistent innervation protects against denervation atrophy and may allow for nerve transfers to treat long-standing lesions within the spinal cord. We tested the hypothesis that in chronic spinal cord lesions, muscles remained viable for reinnervation. METHODS: To test this hypothesis, we operated on 7 patients with tetraplegia to reconstruct thumb and finger extension after a mean interval of 5 years since injury. During surgery, if electrical stimulation of the posterior interosseous nerve (PIN) produced muscle contraction, the nerve to the supinator (NS) was transferred to the PIN. If no contractions were demonstrated, the muscles of the extensor compartment of the forearm were replaced via a free gracilis transfer with innervation supplied by the NS. RESULTS: After an average of 26 months, M3 recovery of thumb and finger extension was observed in the 3 upper limbs from the 2 youngest patients who underwent a nerve transfer. None of the free gracilis-treated patients achieved scores above M2. CONCLUSIONS: In our youngest patients aged 27 and 34 years, who were operated on 6 years after spinal cord injury, transfer of the NS to the PIN partially restored hand span. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic V.

Surgical Anatomy of the Radial Nerve at the Elbow and in the Forearm: Anatomical Basis for Intraplexus Nerve Transfer to Reconstruct Thumb and Finger Extension in C7 - T1 Brachial Plexus Palsy.

Background C7 - T1 palsy results in complete loss of finger motion and poses a surgical challenge. This study investigated the anatomy of the radial nerve in the elbow and forearm and the feasibility of intraplexus nerve transfer to restore thumb and finger extension. Methods The radial nerves were dissected in 28 formalin-fixed upper extremities. Branching pattern, length, diameter, and number of myelinated fibers were recorded. Results Commonly, the branching pattern (from proximal to distal) was to the brachioradialis, extensor carpi radialis longus, superficial sensory proximal to the lateral epicondyle, extensor carpi radialis brevis, supinator, extensor digitorum communis, extensor digiti minimi, extensor carpi ulnaris, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, and extensor indicis distal to the lateral epicondyle. Conclusions Branches to the brachioradialis, extensor carpi radialis longus, and supinator can be transferred to the posterior interosseous nerve to restore hand movement in patients with C7 - T1 brachial plexus palsies; the supinator branch is probably the best choice in this regard.

Transfer of the radial nerve branch to the extensor carpi radialis brevis to the anterior interosseous nerve to reconstruct thumb and finger flexion.

PURPOSE: To report our experiences reconstructing thumb and finger flexion in patients with extensive palsy of the upper limb by transferring the radial nerve branch to the extensor carpi radialis brevis (ECRB) to the anterior interosseous nerve (AIN). METHODS: Within 8 months after injury, 4 patients with either a combined high median/ulnar nerve palsy or C7-T1 brachial plexus root avulsion underwent surgical reconstruction for thumb and finger flexion. As part of the reconstructive procedure, the branch of the radial nerve to the ECRB was transferred to the AIN. RESULTS: At final evaluation, which averaged 13 months postoperatively, all patients had recovered full finger and thumb flexion, scoring M4 per Medical Research Council guidelines. Average grasp strength was 5 kg, and pinch strength was 2 kg. Even in anesthetic fingers and with their eyes closed, patients could correctly identify passive extension of their distal interphalangeal joints. Wrist extension was preserved in all patients. CONCLUSIONS: In 4 patients, transfer of the branch of the radial nerve to the ECRB to the AIN predictably reconstructed thumb and finger flexion. Finger flexion also recovered in those fingers in which the flexor digitorum profundus was primarily innervated by the ulnar nerve. Despite extended sensory deficits, patients ultimately were able to use their hands regularly in daily life. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic III.

Reverse Dorsoradial Flaps for Thumb Coverage Show Increased Sensory Recovery with Smaller Flap Sizes.

BACKGROUND: Reverse homodigital dorsoradial (RHD) flap has been developed to repair soft-tissue defects of the thumb. However, few articles have reported this flap with long-term follow-up. This retrospective study was designed to evaluate the RHD flap and investigate factors affecting sensory recovery. METHODS: From February 2010 to February 2011, 19 patients were treated consecutively with RHD flap without neurorrhaphy. At final follow-up, flap sensibility was assessed by Semmes-Weinstein (SW) monofilament, moving two-point discrimination (M-2PD), and static two-point discrimination (S-2PD) tests. Patient satisfaction, active range-of-motion of the joints, patient complications, and cold intolerance severity score questionnaire were sequentially evaluated. The patients were divided into two groups based on the S-2PD results and another two groups based on flap size. RESULTS: The mean SW monofilament sensitivity and M-2PD and S-2PD scores on the flap were 4.01 g and 9.26 mm, and 10.63 mm, respectively. Highly positive correlations existed between the flap size and the M-2PD and S-2PD scores. Moreover, in the respective groups based on S-2PD scores and flap size, no statistical difference was found among age, sex, and follow-up time, but the flap size and S-2PD scores were statistically different. CONCLUSIONS: RHD flap without neurorrhaphy is a recommendable technique for relatively small-sized thumb-defect reconstruction, which can achieve a satisfactory sensory recovery.

Carpal tunnel syndrome impairs thumb opposition and circumduction motion.

BACKGROUND: Carpal tunnel syndrome is associated with sensory and motor impairments resulting from the compressed and malfunctioning median nerve. The thumb is critical to hand function, yet the pathokinematics of the thumb associated with carpal tunnel syndrome are not well understood. QUESTIONS/PURPOSES: The purpose of this study was to evaluate thumb motion abnormalities associated with carpal tunnel syndrome. We hypothesized that the ranges of translational and angular motion of the thumb would be reduced as a result of carpal tunnel syndrome. METHODS: Eleven patients with carpal tunnel syndrome and 11 healthy control subjects voluntarily participated in this study. Translational and angular kinematics of the thumb were obtained using marker-based video motion analysis during thumb opposition and circumduction movements. RESULTS: Motion deficits were observed for patients with carpal tunnel syndrome even though maximum pinch strength was similar. The path length, normalized by palm width of the thumb tip for the patients with carpal tunnel syndrome was less than for control participants (opposition: 2.2 palm width [95% CI, 1.8-2.6 palm width] versus 3.1 palm width [95% CI, 2.8-3.4 palm width], p < 0.001; circumduction: 2.2 palm width [95% CI, 1.9-2.5 palm width] versus 2.9 palm width [95% CI, 2.7-3.2 palm width], p < 0.001). Specifically, patients with carpal tunnel syndrome had a deficit of 0.3 palm width (95% CI, 0.04-0.52 palm width; p = 0.022) in the maximum position of their thumb tip ulnarly across the palm during opposition relative to control participants. The angular ROM also was reduced for the patients with carpal tunnel syndrome compared with the control participants in extension/flexion for the metacarpophalangeal (opposition: 34° versus 58°, p = .004; circumduction: 33° versus 58°, p < 0.001) and interphalangeal (opposition: 37° versus 62°, p = .028; circumduction: 41° versus 63°, p = .025) joints. CONCLUSIONS: Carpal tunnel syndrome disrupts kinematics of the thumb during opposition and circumduction despite normal pinch strength. CLINICAL RELEVANCE: Improving understanding of thumb pathokinematics associated with carpal tunnel syndrome may help clarify hand function impairment associated with the syndrome given the critical role of the thumb in dexterous manipulation.