Finger Sensibility Research Articles

Recovery of finger sensibility and somatosensory evoked potentials following digit-to-digit replantation in man

Recovery of finger sensation and digital nerve function following digit-to-digit replantation was studied in 14 patients by clinical sensory evaluation and somatosensory evoked potentials (SEP) to digital nerve stimulation. The mean interval between injury and surgery was 8 +/- 3h; that between surgery and study was 25 +/- 7 months. Sensory examination revealed a mild hypersensitivity to cold. Pinprick, touch and hot sensations had nearly complete recovery, while vibration and two-point discrimination were impaired. In digital SEPs from the replanted side, the N9 component was present and normal in 8 patients (57%), whereas the N13 and N20 components had prolonged latency with normal central conduction time. Absence of the N9 component appeared to correlate with a more proximal level of injury and poor surgical outcome. The present data indicate that sensory recovery of the replanted digits was in general satisfactory but incomplete, and that over half of the patients had normal digital nerve conduction.

Individual Finger Sensibility in Carpal Tunnel Syndrome

Individual Finger Sensibility in Carpal Tunnel Syndrome

Individual Finger Sensibility in Carpal Tunnel Syndrome

Sensibility testing plays a role in the diagnosis of carpal tunnel syndrome (CTS). No single physical examination test has proven to be of critical value in the diagnosis, especially when compared with electrodiagnostic testing (EDX). The purpose of this study was to define which digits are most affected by CTS, both subjectively and with objective sensibility testing. A prospective series of 35 patients (40 hands) with EDX-positive, isolated CTS were evaluated preoperatively using 2 objective sensibility tests: static 2-point discrimination (2PD) and abbreviated Semmes-Weinstein monofilament (SWMF) testing. Detailed surveys of subjective symptoms were also collected. Patients identified the middle finger as the most symptomatic over all others (51%). Objective 2PD results of each digit mirrored the subjective data, with higher values for the middle finger (mean 6.07 mm, (p < .0001). Values for the index finger failed to show a significant difference from the ulnar-innervated small finger. The most symptomatic finger matched 2PD results in over two thirds of patients. The SWMF testing showed similar, statistically significant results (middle > thumb > index > small). Correlations failed between EDX, symptoms, and SWMF results or 2PD in the index finger. Positive but weak correlation (p = .002, r = .42) was found between EDX and 2PD only in the middle fingers. The middle finger is the most likely to show changes in 2PD in patients with positive EDX findings for CTS. Middle finger 2PD is best able to correlate with EDX when compared with 2PD of other digits. The SWMF testing also shows the middle digit testing as more sensitive, but this finding may be difficult to use clinically. Diagnostic I.

Results of Zone II Flexor Tendon Repair in Children Younger Than Age 6 Years

The inability of young children with a zone II flexor tendon repair to cooperate in postoperative care and rehabilitation may represent a high risk for medical and surgical complications. To forestall that risk, botulinum toxin type A (2.5 U/kg, 7 U/kg) injection was used during surgery to induce forearm flexor muscle relaxation in seven children under 6 years old with zone 2 flexor tendon repairs. Patients received a controlled passive motion regimen after surgery. Results were evaluated on the basis of the acquisition of muscle tone and active finger movements, total range of motion of affected joints, postoperative grip strength, muscle atrophy, and phalangeal length. In this prospective clinical study, the mean follow-up was 18 months. All the children had good and excellent results based on the Strickland criteria. As for postoperative complications, one patient had bowstring and another had poor finger sensibility and first web space contracture that required Z-plasty. The selective use of botulinum toxin type A to weaken the targeted muscles generated a sufficient reduction in spontaneous activity of the fingers, permitting an improved rehabilitation program. Botulinum toxin type A administration could be an effective form of therapy, serving as an alternative or adjunct to conventional rehabilitation modalities in these children.

The role of cutaneous feedback for anticipatory grip force adjustments during object movements and externally imposed variation of the direction of gravity

Grip force adjustments to changes of object loading induced by external changes of the direction of gravity during discrete arm movements with a grasped object were analyzed during normal and anesthetized finger sensibility. Two subjects were seated upright in a rotatable chair and rotated backwards into a horizontal position during discrete movements with a hand-held instrumented object. The movement direction varied from vertical to horizontal inducing corresponding changes in the direction of gravity, but the orientation of the movement in relation to the body remained unaffected. During discrete vertical movements a maximum of load force occurs early in upward and late in downward movements; during horizontal movements two load force peaks result from both acceleratory and deceleratory phases of the movement. During performance with normal finger sensibility grip force was modulated in parallel with fluctuations of load force during vertical and horizontal movements. The grip force profile adopted to the varying load force profile during the transition from the vertical to the horizontal position. The maximum grip force occurred at the same time of maximum load force irrespective of the movement plane. During both subjects' first experience of digital anesthesia the object slipped from the grasp during rotation to the horizontal plane. During the following trials with anesthetized fingers subjects substantially increased their grip forces, resulting in elevated force ratios between maximum grip and load force. However, grip force was still modulated with the movement-induced load fluctuations and maximum grip force coincided with maximum load force during vertical and horizontal movements. This implies that the elevated force ratio between maximum grip and load force does not alter the feedforward system of grip force control. Cutaneous afferent information from the grasping digits seems to be important for the economic scaling of the grip force magnitude according to the actual loading conditions and for reactive grip force adjustments in response to load perturbations. However, it plays a subordinate role for the precise anticipatory temporal coupling between grip and load forces during voluntary object manipulation.

The effects of digital anaesthesia on predictive grip force adjustments during vertical movements of a grasped object.

Grip force adjustments to fluctuations of inertial loads induced by vertical arm movements with a grasped object were analysed during normal and impaired finger sensibility. Normally grip force is modulated in a highly economical way in parallel with fluctuations of load force. Two subjects performed vertical up and down movements of a grasped object, both with normal finger sensibility and then cutaneously anaesthetized finger sensibility. Short breaks were taken in between single movements, during which the object was held stationary. After digital anaesthesia was applied to the grasping fingers, both subjects substantially increased the grip force. The grip force amplitude and timing still anticipated changes in load force, although the established grip force had already overcome movement-induced load force peaks. This implies that the increase of grip force and consequently the elevated force ratio between maximum grip and maximum load force are not processed to alter the feedforward system of grip force control. Cutaneous afferent information from the grasping digits appears to be necessary for economic scaling of the grip force level, but it plays a subordinate role in the precise anticipatory temporal coupling of grip and load forces during voluntary object manipulation.

Recovery of finger sensibility and somatosensory evoked potentials following digit-to-digit replantation in man

Recovery of finger sensation and digital nerve function following digit-to-digit replantation was studied in 14 patients by clinical sensory evaluation and somatosensory evoked potentials (SEP) to digital nerve stimulation. The mean interval between injury and surgery was 8 +/- 3h; that between surgery and study was 25 +/- 7 months. Sensory examination revealed a mild hypersensitivity to cold. Pinprick, touch and hot sensations had nearly complete recovery, while vibration and two-point discrimination were impaired. In digital SEPs from the replanted side, the N9 component was present and normal in 8 patients (57%), whereas the N13 and N20 components had prolonged latency with normal central conduction time. Absence of the N9 component appeared to correlate with a more proximal level of injury and poor surgical outcome. The present data indicate that sensory recovery of the replanted digits was in general satisfactory but incomplete, and that over half of the patients had normal digital nerve conduction.

A New Nerve Pedicle for Finger Sensibility

Restoration of sensibility to the traumatized finger can be a difficult problem. Two patients with insensibility to the volar distal finger after trauma underwent delayed digital nerve repair. In the first patient, the dorsal branch of the radial proper digital nerve was approximated to the distal stump as a pedicle to span a 12-mm gap resulting from neuroma excision. The second patient had a 14-mm defect after scar-tissue excision 8 months following primary neurorrhaphy after trauma. Reconstruction was performed by approximating the dorsal branch of the radial proper digital nerve to the distal stump. Both patients had fingertip sensibility restored 1 year postoperatively, as documented by two-point discrimination. Anatomic dissections of 12 fresh cadaver fingers revealed a consistent pattern. Of the 24 proper digital nerves dissected, 23 had a distal dorsal sensory branch arising at the midportion of the proximal phalanx. The dorsal branch-vascularized pedicle of the proper digital nerve has not been described previously as a method for restoring finger sensibility in cases not amenable to primary neurorrhaphy. We believe this technique should be added to the repertoire of the practicing hand surgeon.

Restoration of sensibility in fingers repaired with free sensory flaps from the toe

The sensibility of 25 fingers reconstructed with three different types of free sensory flaps from the toe was evaluated. The relationships between sensory restoration and the patient's age, type of sensory flap, selection of sutured nerves, and circulatory complications in the flap were analyzed. Wrap-around flaps were used in 5 fingers, hemipulp flaps in 11, and toe-to-finger transfers in 9. The follow-up period ranged from 16 to 79 months. Restoration of sensibility in the flap was closely related to the patient's age and vascular insufficiency of the flap. Therefore, establishing and maintaining an adequate circulation in the flap at operation is essential for good sensory restoration.