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Two-point discrimination distances in the normal hand and forearm: application to various methods of fingertip reconstruction.

Two-point discrimination in the hand and forearm is best during the third decade of life. In the fingertips, the ulnar digits are more discriminating than the radial digits. Males and females have equal two-point discrimination during each age decade. Fingertips are twice as discriminating as the thenar and hypothenar areas, and the thenar and hypothenar areas are twice as discriminating as the volar side of the wrist; the wrist is twice as discriminating as the forearm. The Kleinert and Kutler flaps demonstrated the best two-point discrimination among the repaired fingertips.

Adolescent

A single session of high-definition transcranial direct current stimulation does not modulate effects of knee two-point discrimination training or sensorimotor function in healthy adults: Double-blind randomised controlled trial.

BACKGROUND: Benefits of sensory-training interventions on sensorimotor outcomes are inconsistent, and it is unclear whether transcranial direct current stimulation (tDCS) can enhance proprioception, which is fundamental to neuromuscular control. Existing evidence is dominated by upper-limb studies, so transferability to the knee is unclear. This study investigated whether a single session of anodal high-definition (HD)-tDCS, alone or combined with brief two-point discrimination (TPD) training, enhances knee sensorimotor function and performance in healthy adults. METHODS: In a double-blind randomised-controlled trial, 57 healthy participants received (1) 20-min, 1&#xa0;mA anodal HD-tDCS over the knee primary somatosensory (S1) map or sham stimulation, and (2) 15-min knee TPD training or no training. Knee somatosensory, sensorimotor, and functional performance measures were assessed pre- and immediately post-intervention. Three-way mixed-design ANOVAs, equivalence testing (smallest effect size of interest &#x3b7;2&#xa0;=&#xa0;0.02), Bayes factors, and linear mixed-effects models quantified effects. RESULTS: HD-tDCS, TPD training, and their sequential combination had no effect on any outcome measure (p&#xa0;&#x2265;&#xa0;0.05; &#x3b7;2&#xa0;&#x2264;&#xa0;0.015). Confidence intervals spanned equivalence bounds, and equivalence testing results were non-significant (p&#xa0;&#x2265;&#xa0;0.05). Bayes factors (<0.33) showed moderate evidence for the null (no effect). Mixed-effects modelling attributed &#x2264;8% of total variance to intervention fixed effects, with the remainder captured by participant-level random effects. CONCLUSION: A single 20-minute session of 1&#xa0;mA HD-tDCS, with or without brief TPD training, does not acutely modify knee somatosensory, sensorimotor, or functional performance in healthy adults. Existing evidence at the hand may not translate to the lower limb. Future work should investigate higher-dose, multi-session, task-concurrent, or network-targeted strategies in clinical populations.

Humans

The moving two-point discrimination test: clinical evaluation of the quickly adapting fiber/receptor system.

As the Weber test evaluates the slowly adapting fiber-receptor system (constant touch), the "moving two-point discrimination test" evaluates the innervation density of the quickly adapting fiber-receptor system which mediates the perception of touch stimuli moving across the hand. Results with this test in 39 hands used as controls and in 63 patients with nerve injuries show it to be a simple, quick, and valid diagnostic tool in nerve compression syndromes and nerve lacerations and an accurate prognosticator and monitor during sensory reeducation following nerve repair.

Adolescent

Recovery of sensibility after suture of digital nerves.

A group of 49 patients with 74 injured digital nerves was studied more than 5 years following epineurial nerve suture. Three tests of return of sensibility were used: von Frey plastic filaments, a modified Weber two-point discrimination device, and a dynamic test--the plastic ridge. The correlation between two-point discrimination and tactilegnosis in the range of 8 to 12 mm was poor. The plastic ridge device detects the presence or absence of tactilegnosis in patients in the intermediate range of two-point discrimination between 8 and 12 mm. Of the factors studied, the patient's age at the time of nerve suture was found to be directly related to the return of sensibility by both two-point discrimination and ridge criteria.

Adolescent

Manual and oral sensation in patients with Cushing's syndrome.

Thresholds for light touch detection and two-point discrimination on the hand and in the mouth, and oral and manual stereognosis ability were measured in patients with untreated Cushing's syndrome and normal volunteers. Results indicated that patients with Cushing's syndrome displayed decreased two-point discrimination on the tongue and palate and decreased oral stereognosis.

Adult

Instrumentation for measurement of sensory loss in the fingertips.

Four aesthesiometers measuring fingertip sensation were fabricated, two for depth-sense perception and two for two-point discrimination. With the use of 20 normal subjects (10 female and 10 male) and seven subjects with vasospastic disturbance (three female and four male) comparisons were made to determine which of each pair of instruments was the more sensitive. The results indicated that instrument A is preferable to B in measuring depth-sense perception, and C is preferable to D in measuring two-point discrimination. Females appear to have more acute sensory perception than males. Female and male patients diagnosed as having "Raynaud's disease" show a loss in fingertip sensory perception.

Female

Free neurovascular flap from the first web of the foot in hand reconstruction.

To identify an anatomically reliable and functionally acceptable neurovascular free flap for use in hand reconstruction, 50 fresh cadaver feet were dissected under the operating microscope, with particular attention paid to the anatomy of the first web area. A distal communicating artery was seen in 100% of dissections, allowing either dorsal or plantar donor artery inflow to nourish the entire flap area. Because of the ease of dissection, the first dorsal metatarsal or dorsalis pedis is suggested as the donor artery, and a dorsal branch of the greater saphenous venous system is suggested as the donor vein. The deep peroneal nerve was seen to consistently innervate the first web and, along with the plantar digital nerves, is suggested as an anatomically identifiable donor nerve. Either part of the foot first web may be used alone or together as a free flap. When indicated further dorsal skin may be incorporated into the web flap to expand its application. Two-point discrimination studies of the lateral plantar surface of the great toe in 50 normal individuals showed an average of 11.2 mm. This was significantly better as a potential donor flap than the medial dorsum of the foot where the average was 32 mm. A single case demonstrating the application of this flap in hand reconstruction is presented.

Adolescent

Distal digital nerve grafts: clinical and anatomical studies.

An anatomical study of the terminal branches of the digital nerves of thumb and finger indicated a constant trifurcation at the level of the distal interphalangeal joint. Twelve microscopic interfascicular nerve grafts were done in 11 patients who had nerve division at this level with insensitive fingertips. All patients exhibited improved sensibility. Eight of 12 or 67% achieved 6 mm of two-point discrimination. Although there were no children in this study, the subjects under 30 years of age enjoyed better final results.

Adolescent

Oral sensory and motor behaviors of children with /s/ or /r/ misarticulations.

Measurements of lingual two-point discrimination, oral form discrimination, and alternate motion rate of the tongue were made in 15 children who had normal articulation, 15 children who misarticulated /s/, and 15 children who misarticulated /r/. The two groups of children with misarticulations were found to differ from each other as well as from normal children on various aspects of oral sensation and motor abilities. These findings are interpreted as evidence for the existence of different bases for the misarticulations of the two disordered groups.

Adolescent

Free toe-to-fingertip neurovascular flaps.

Six cases of free toe-to-fingertip neurovascular flaps are presented. The principal advantages of this procedure over rotation island flaps are (1) achievement of better two-point discrimination, (2) an acceptable donor defect, (3) no cortical reorientation is necessary, and (4) there is minimal tension on the nerve.

Adolescent

Carpal tunnel syndrome in pregnancy.

Occurrence of the carpal tunnel syndrome in pregnancy was studied by examining 100 consecutive obstetric admissions. Twenty-one patients reported paresthesias or hypesthesia in the median nerve sensory distribution of the hand during the pregnancy; eight of these had decreased sensation subjectively at the time of examination one to three days after delivery; two had trophic changes, loss of sudomotor function, thenar atrophy, and decreased two-point discrimination; and one had a delay in motor conduction time across the carpal tunnel. Of the 21 patients, 18 became asymptomatic before or shortly after delivery. The remaining three were asymptomatic three months after delivery. We conclude that the incidence of symptoms is probably greater than usually appreciated, but that few patients require treatment. Steroid injection may occassionally be necessary, but the need for surgical intervention is rare.

Carpal Tunnel Syndrome

Prevalence of vibration-induced white finger in fluorspar mines in Weardale.

A combined epidemiological and clinical study of vibration-induced white finger (VWF) was carried out involving 115 men in four fluorspar mines. The overall prevalence of VWF was found to be 50% among 42 vibration-exposed subjects, while that of constitutional white finger (CWF) was 5-6% in all men studied. The VWF latent interval was 1-19 years with a mean of 5-6 years. An association was observed between the exposure time and VWF stages which included 18 men in Stage 0, three in the intermediate Stage of 0T/0N, five in Stage 2 and 16 in Stage 3; no men were seen at Stage 1. Among those with VWF in Stage 3, the index, middle and ring fingers were affected in both hands and the little fingers and thumbs were last to be involved. Clinically, on general examination, apart from vibration-induced white finger, the men in the 'vibration' group were not as healthy as those in the 'control' group. The circumference of the index fingers was not significantly different for the different groups. Neurological tests showed that the ridge test and, to a lesser extent, the two-point discrimination and the light touch tests, could be regarded as useful for the diagnosis of VWF.

Adolescent

Inversion or pronation of the foot following thalamotomy for Parkinson's disease.

The author has observed inward turning of the foot of 2 parkinsonian patients following thalamotomy on the contralateral side. In one instance, the surgery was unilateral and in the other bilateral. The anatomical position of the involved lesions was in the region of the complex of the ventrocaudal nuclei (ventralis posterolateralis). It appears that three elements are present whenever such pronation of the foot occurs, namely, paresis, hypertonicity, and impairment of sensory modalities such as localization, two-point discrimination and vibration.

Female

The protective value of a neurovascular island pedicle transfer in hands partially anesthetic due to ulnar denervation in leprosy.

Neurovascular skin island transfers were performed with the prime objective of protecting vulnerable anesthetic areas on the hands of patients with leprosy. After an average follow-up of eight years on sixteen patients, all had long-lasting protective benefits without further loss of tissue consequent to injury. At follow-up, two-point discrimination was less than ten millimeters in only one patient, more than twenty millimeters in ten, and indeterminate in five. Sensory misreference persisted in fourteen patients. Axon sprouting was evident in six but only over short distances (four to eight millimeters beyond the island). Compared with the intact side of the donor finger, nine of the sixteen transfers had lost some sensitivity but sensation was rated normal in one, nearly normal in six, and protective only in nine. The loss of sensation in the donor finger was less than expected and was not a problem. Scar contracture occurred in two donor and five recipient fingers, but this could be attributed to placement of the incision too far anteriorly, and hence was an unavoidable complication. Restoration of protective sensation to the ulnar border of the hand, whatever the cause of anesthesia, is considered extremely worth while.

Adolescent

Neurovascular free foot flaps in reconstruction of the mutilated hand.

The neurovascular free flap from the first web region of the foot affords unrivalled potential for refurbishing sensibility to the denervated hand. Its greatest application is when no conventional island flap tissue remains for transfer. Its two-point discrimination is only moderate, but when used for thumb reconstruction, its sensibility is adequate because no functional substitute exists. Functionally and cosmetically it is superior to other methods of thumb reconstruction because of its pulp, size, and nail availability. There are no finger identification problems and secondary donor defects are minimal.

Adult

[Effect of various forms of physical exertion on selected types of sensory function].

The author reports changes in vibration and two-point discrimation sensitivity in groups of healthy young males after several days of intense physical effort and after one short-lasting intense exercise. The vibration sensitivity was a steady type of sensory function showing no significant changes after these workloads. The two-point discrimination sensitivity was, not infrequently, better after several days of effort in relation to preliminary state, and it was regarded as an evidence of adaptation to work. On the other hand, one sort-lasting exercise reduced significantly discrimination of two stimuli, especially on the lower extremities. This significant impairment of two-stimuli discrimination on the lower extremities in relation to the upper ones after intensive effort suggests easier exhaustion of pathways conveying sensation in the thoracic segment of the spinal cord. On the basis of these investigations the author thinks that aesthesiometric investigations carried out under strictly observed conditions may be useful for assessment of fatigue.

Adult

[Functional improvement in the treatment of large soft tissue defects of the thumb by a free tissue transplant].

The advantages of free transplantation used to cover defects of the thumb are demonstrated with the aid of a clinical example. A 27 years old patient had lost large parts of the covering soft tissue as well as the nerves and vessels on the flexor side of the distal phalanx of his left thumb. After a single wound toilet the thumb could hardly be used because of the reduced mechanical resistance to stress, the missing sensibility and a severely disturbed circulation. This kind of large soft tissue defect at a functionally important location can now be covered with a free composite tissue transplantation. We took a neurovascular flap out of this patient's forefoot and anastomosed it with the vessels and nerves of the proximal phalanx of the thumb. After an uncomplicated healing the covering soft tissue could be mechanically stressed and was well supplied with blood. Three month later a beginning sensibility can be proved. After 2 years the fully rehabilitated patient shows a good functional result with a two-point discrimination of 10 millimeters.

Adult