Index Fingertip Research Articles

Foster replantation of fingertip using neighbouring digital artery in a young child

Reconstruction of an amputated fingertip in a young child demands special techniques for success. We report a 2.5-year-old female patient with an amputated left index fingertip with the vascular defect being too severe to perform the usual replantation. Comparing several methods, we used the neighbouring digital artery as the feeding artery to perform foster replantation. Finally, the patient was satisfied with the appearance and function of her fingers. The clinical case, techniques, results are described and discussed. We consider it a useful technique, especially for those with a rather severe vascular defect. A 2.5-year-old girl suffered a crush amputation of the left index fingertip. Only the flexor tendon of the amputated fingertip was connected to the proximal finger tissue and the blood supply was completely lost (Figure 1). The distal amputated fingertip was fixed using Kirschner wire under general anaesthesia. Then, microsurgery operation was carried out immediately to replant this amputated fingertip. Both ulnar and radial digital arteries were avulsed, while the dorsal vein was intact and the digital nerve was also surviving. The integrity of blood vessels was too traumatised to connect to the proximal part. In the case of the distal part of the ulnar artery of the injured index finger, the blood supply was established by anastomosing the distal end of the amputated tip and the radial artery of the middle finger, which was the feeding artery (Figure 2). A 11/0 nylon suture was used. The dorsal vein and digital nerve were repaired by means of microsurgical anastomosis. The wound was covered with the dorsal skin of the middle finger and the palmar skin of the index finger to form a skin pedicle, and then, immobility of the two fingers was maintained to prevent avulsion. The index tip obtained good blood supply and survived completely (Figure 3). Detachment of the index and middle finger was performed after 3 weeks, and both of the fingers showed good blood supply (Figure 4). The appearance and function of the index and middle fingers were satisfactory 3 months postoperatively.

Tactile roughness discrimination threshold is unrelated to tactile spatial acuity

The present study examined the relationship between the tactile roughness discrimination threshold (TRDT) and the tactile spatial resolution threshold (TSRT) at the index fingertip in humans. A new device was built for measuring TRDT, allowing pair-wise presentations of two sets of six different sandpaper grits. The smoothest grits ranged from 18 to 40 μm and the roughest grits ranged from 50 to 195 μm particle size. The reference sandpaper had a 46 μm particle size. A two-alternative forced choice paradigm and a double interlaced adaptive staircase procedure yielding a 75% just noticeable difference (75%jnd) was used according to Zwislocki and Relkin [28]. Contact force and scanning velocity were measured at the fingertip with a built-in sensor. The TSRT was assessed with an extended set of grating domes. Fifty-three male and female subjects, spanning a wide age range participated in this study. The JND75% or TRDT was lower for the smoothest sandpapers (15 ± 8.5 μm) compared to the roughest sandpapers (44 ± 32.5 μm). TRDT performance was unrelated to age or gender. Additionally, grit size had no effect on the mean forces (normal and tangential) exerted at the fingertip or the mean scan velocities. In contrast, there was a significant degradation of TSRT performance with age. Lastly, there was no significant correlation between TRDT and TRST performance. Results of this study support the theory that the neural mechanisms underlying the perception of tactile roughness discrimination for fine textures differ from those involved in spatial resolution acuity often associated with the SA1 afferents.

Diminutive Digits Discern Delicate Details: Fingertip Size and the Sex Difference in Tactile Spatial Acuity

We have observed that passive tactile spatial acuity, the ability to resolve the spatial structure of surfaces pressed upon the skin, differs subtly but consistently between the sexes, with women able to perceive finer surface detail than men. Eschewing complex central explanations, we hypothesized that this sex difference in somatosensory perception might result from simple physical differences between the fingers of women and men. To investigate, we tested 50 women and 50 men on a tactile grating orientation task and measured the surface area of the participants' index fingertips. In subsets of participants, we additionally measured finger skin compliance and optically imaged the fingerprint microstructure to count sweat pores. We show here that tactile perception improves with decreasing finger size, and that this correlation fully explains the better perception of women, who on average have smaller fingers than men. Indeed, when sex and finger size are both considered in statistical analyses, only finger size predicts tactile acuity. Thus, a man and a woman with fingers of equal size will, on average, enjoy equal tactile acuity. We further show that sweat pores, and presumably the Merkel receptors beneath them, are packed more densely in smaller fingers.

Exposure of Treating Physician to Radiation during Prostate Brachytherapy Using Iodine-125 Seeds

Only sparse reports have been made about radiation exposure of the treating physician during prostate seed implantation. Therefore, thermoluminescence dosimeter (TLD) measurements on the index fingers and the backs of both hands were conducted. Stranded iodine-125 seeds with a mean apparent activity of 27.4 MBq per seed were used. During application, the treating physician manipulated the loaded needle with the index fingers, partially under fluoroscopic control. Four physicians with varying experience treated 24 patients. The radiation exposure was determined with TLD-100 chips attached to the index fingertips and the backs of hands. Radiation exposure was correlated with the physician's experience. The average brachytherapy duration by the most experienced physician was 19.2 min (standard deviation sigma = 1.2 min; novices: 34.8 min [sigma = 10.2 min]). The mean activity was 1,703 MBq (sigma = 123 MBq), applied with 16.3 needles (sigma = 2.5 needles; novices: 1,469 MBq [sigma = 229 MBq]; 16.8 needles [sigma = 2.3 needles]). The exposure of the finger of the "active hand" and the back of the hand amounted to 1.31 mSv (sigma = 0.54 mSv) and 0.61 mSv (sigma = 0.23 mSv), respectively (novices: 2.07 mSv [sigma = 0.86 mSv] and 1.05 mSv [sigma = 0.53 mSv]). If no other radiation exposure needs to be considered, an experienced physician can perform about 400 applications per year without exceeding the limit of 500 mSv/year; for novices, the corresponding figure is about 200.

How Reliable Is the Determination of Cervical Dilation? Comparison of Vaginal Examination With Spatial Position-Tracking Ruler

The traditional method for assessment of cervical dilation—vaginal examination—is subjective and has an accuracy of less than 60%. Although several devices for cervical dilation assessment have been developed, few have survived and cervical assessment is still performed by vaginal examination worldwide. This prospective study compared the accuracy of clinical measurement of cervical dilation for 2 methods, vaginal examination and use of a position-tracking system. The study subjects, enrolled at 3 centers (Poissy, France; Brooklyn, NY; and Haifa, Israel), were 188 singleton women in active labor with vertex presentation and no known contraindication to vaginal examination. For each routine vaginal examination, a sensor was attached to the midwife’s index fingertip and measurement was performed with a magnetic position tracking system, using personal computer-based controlling software, and ultrasound imaging technology. A total of 333 measurements were performed with the tracking system. Ninety cases with clinically full dilation were excluded from analysis. The data from the 3 centers were pooled; results were similar in each. There was an overall mean absolute difference of 10.2 ± 8.4 mm between the 2 methods. Analysis of subgroups stratified by dilation showed that the absolute difference was 7.5 ± 7.3 mm (70.0% accuracy) when the cervical dilation was >8 cm and 12.5 ± 8.7 mm (38.8% accuracy) when the cervical dilation was between 6.1 and 8 cm. These findings show that the accuracy of the positron-tracking system for assessment of cervical dilation during labor appears to be limited. The clinical relevance of this system in routine care is unclear and requires further evaluation.

Assessment of Sensory Function in the National Social Life, Health, and Aging Project

The National Social Life, Health, and Aging Project assessed functioning of all 5 senses using both self-report and objective measures. We evaluate the performance of the objective measures and model differences in sensory function by gender and age. In the process, we demonstrate how to use and interpret these measures. Distance vision was assessed using a standard Sloan eye chart, and touch was measured using a stationary 2-point discrimination test applied to the index fingertip of the dominant hand. Olfactory function (both intensity detection and odor identification) was assessed using odorants administered via felt-tip pens. Gustatory function was measured via identification of four taste strips. The performance of the objective measures was similar to that reported for previous studies, as was the relationship between sensory function and both gender and age. Sensory function is important in studies of aging and health both because it is an important health outcome and also because a decline in functioning can be symptomatic of or predict other health conditions. Although the objective measures provide considerably more precision than the self-report items, the latter can be valuable for imputation of missing data and for understanding differences in how older adults perceive their own sensory ability.

CHARACTERIZATION OF FINGER ISOMETRIC FORCE PRODUCTION WITH MAXIMUM POWER OF SURFACE ELECTROMYOGRAPHY

Finger's action has been controlled by both intrinsic and extrinsic hand muscles. Characterizing the finger action with the activations of hand muscles could be useful for evaluating the neuromuscular control strategy of finger's motor functions. This study is designed to explore the correlation of isometric fingertip force production and frequency-domain features of surface electromyography (sEMG) recorded on extrinsic hand muscles. To this end, 13 subjects (five male and eight female university students) have been recruited to conduct a target force-tracking task. Each subject is required to produce a certain level of force with either the index or middle fingertip to match the pseudo-random ordered target force level (4N, 6N, or 8N) as accurate as possible. During the finger force production process, the sEMG signals are recorded on two extrinsic hand muscles: flex digitorum superficials (FDS) and extensor digitorum (ED). For each sEMG trail, the power spectrum is estimated with the autoregressive (AR) model and from which the maximum power is obtained. Our experimental results reveal three findings: (1) the maximum power increases with the force level regardless of the force producing finger (i.e. index or middle) and the extrinsic hand muscle (i.e. FDS or ED). (2) The sEMG maximum power of index finger is significantly lower than that of the middle finger under the same force level and extrinsic hand muscle. (3) No significant difference can be found between the maximum powers of FDS and ED. The results indicate that the activations of the extrinsic muscles are affected by both the force level and the force producing finger. Based on our findings, the sEMG maximum power of the extrinsic hand muscles could be used as a key parameter to describe the finger's actions.

How reliable is the determination of cervical dilation? Comparison of vaginal examination with spatial position-tracking ruler

The purpose of this study was to evaluate the accuracy of clinical measurement of cervical dilation with a position-tracking system during vaginal examination. This prospective study that was conducted in Poissy, France, Brooklyn, NY, and Haifa, Israel, included 333 measurements that were performed in 188 women with term singleton vertex uncomplicated pregnancies during the active stage of labor. Ninety measurements with clinical diagnosis of full dilation were excluded from analysis. Measurements were performed with a sensor attached to the midwife's index fingertip and a position-tracking system that was based on a low magnetic field. Evaluations were done when cervical examinations were clinically indicated. Results were similar in all centers. Mean error was 10.2 +/- 8.4 mm and ranged from 7.5 +/- 7.3 mm, when cervical dilation was > 8 cm, to 12.5 +/- 8.7 mm when cervical dilation was between 6.1 and 8 cm. This first evaluation of cervical assessment accuracy during vaginal examination with a position-tracking system shows limited precision.

Symplastic Glomus Tumor: A Case Report

Symplastic glomus tumors are defined as glomus tumors with a high-grade nuclear pleomorphism in the absence of any other malignant features, such as large size, deep location, infiltrative growth, mitotic activity, or necrosis. Only 11 cases have been reported so far in the English literature. It could be a challenge for pathologists who have no experience with it because the tumor can show marked nuclear atypia and pleomorphism. Despite its high nuclear grade, a symplastic glomus tumor itself has a benign biologic behavior. Hereby, the authors report a case of a symplastic glomus tumor on the right index finger tip of a 44-year-old woman with a literature review.

A BLAUTH IIIB HYPOPLASTIC THUMB RECONSTRUCTED WITH A VASCULARISED METATARSO-PHALANGEAL JOINT TRANSFER: A CASE REPORT WITH 28 YEARS OF FOLLOW UP

We reconstructed the Blauth-IIIB hypoplastic right thumb of a 16-year-old girl with a vascularised metatarso-phalangeal (MTP) joint from her second toe combined with a dorsalis-pedis flap. Abduction was provided with an abductor policis long tendon advancement, and adduction, with an extensor indicis proprius tendon transfer. Opponoplasty was performed one year later using the flexor sublimis (IV) tendon. The transferred joint remained functional and non-osteoarthritic 28 years later. Radial and palmar abduction of the reconstructed thumb was 45 degrees and 75 degrees respectively. The index, middle, and ring fingers could oppose the thumb, however she grasped small objects between her index and middle fingertips. If a pollicisation using the index finger is not accepted, the reconstruction described here is one of the surgical options. However donor-foot morbidity is not negligible. Currently, we use a proximal-interphalangeal joint transfer with an opponoplasty using an abductor digiti minimi as a first choice, when planning a reconstruction of preserved hypoplasic thumb.

Spatial acuity and summation on the hand: The role of thermal cues in material discrimination

The spatial characteristics of thermal perception were studied in two experiments that examined how thermal stimuli are processed within the hands. A thermal display that simulates cues associated with making contact with different materials was used in these studies. In the first experiment, participants indicated which of two simulated materials that were presented to the index fingertip was cooler. The results indicated that participants were unable to resolve the two areas of thermal stimulation. In the second experiment, the effects of concurrent thermal stimulation on the ability to discriminate between simulated materials were evaluated. Thermal cues were presented to the middle fingers of both hands and to two adjacent fingers on one hand. Thermal spatial summation was evident across the fingers, which enhanced the ability to discriminate between materials when the cooler stimulus was presented to three fingers. When the same stimulus was presented to the two hands, the stimulation of adjacent fingers altered the perceived thermal response.

Receptive Field Characteristics Under Electrotactile Stimulation of the Fingertip

Skin on human fingertips has high concentrations of mechanoreceptors, which are used to provide fine resolution tactile representations of our environment. Here, we explore the ability to discriminate electrotactile stimulation at four sites on the fingertip. Electrical stimulation was delivered to arrays of electrodes centered on the index fingertip (volar aspect). Accuracy of discrimination was tested by examining electrode size, interelectrode spacing, and stimulation frequency as primary factors. Electrical stimulation was delivered at 2 mA with the pulse width modulated to be at (or above) perceptual threshold at 25 and 75 Hz and an average pulse width of 1.03 ms (+/- 0.70 ms standard deviation). Discrimination of the stimulated locations under this stimulation paradigm was significantly above chance level in all cases. Subjects' ability to discriminate stimulus location was not significantly influenced by electrode size or stimulation frequency when considered as separate factors. However, increased electrode spacing significantly increased subjects' ability to discriminate the location of the stimulated electrode. Further analysis revealed that errors were only significantly reduced along the medial-lateral direction with increasing interelectrode spacing. These results suggest that the electrotactile stimulus localization on the fingertip has some directional dependency, in addition to its dependency on interelectrode spacing. The neural mechanisms underlying this phenomenon are discussed in relation to electrical stimulus transduction characteristics of tactile mechanoreceptors.

Ratio of Fourth to Second Fingertip Extensions in Relation to Serum Estradiol and Testosterone Levels in Men and Women

Sex differences in second (2D) and fourth (4D) fingertip extensions relative to the middle fingertip and 4D:2D fingertip extension ratios were studied in men and women. Body height positively correlated with index fingertip extensions, not with ring fingertip extensions, nor with their ratio. Mean 2D extension (both hands) was smaller in women than men; mean 4D extension (right hand) was smaller in men than women; 4D:2D fingertip extension ratios from both hands were larger in women than men. Serum estradiol concentration negatively correlated with 2D extensions for both hands (no significant correlation with 4D extensions), but positively correlated with 4D:2D extension ratios for both hands. Serum testosterone concentration positively correlated with 2D extensions of both hands (no significant correlation with 4D extension), but negatively correlated with 4D:2D extension ratios for both hands. These relations were also studied in men and women separately. It was concluded that the 4D:2D extension ratio was greater in women than in men; 2D and 4D extensions and 4D:2D extension ratios may be determined prenatally by sex hormones; fingertip extensions may be predictive of adult and prenatal sex hormone levels.

Sympathetic sweat responses and skin vasomotor reflexes in carpal tunnel syndrome

Objective To investigate cutaneous sympathetic functions in carpal tunnel syndrome (CTS) using sympathetic sweat responses (SSwRs) and skin vasomotor reflexes (SVmRs). Methods In 29 hands (20 patients) with idiopathic CTS, SSwRs were recorded with a sudorometer from the thenar eminence, and SVmRs were used to measure cutaneous blood flow using a Doppler flowmeter placed on the index finger tip. Normal data were obtained from 15 volunteers of similar age. Results SSwRs or SVmRs were abnormal in 23 (80%) hands; SSwRs were absent in 38%, whereas SVmRs were abnormally decreased in 59%. Autonomic symptoms were present in 18 (62%) hands; finger edema (38%) and dry hand (35%) were frequent symptoms. Autonomic symptoms, and abnormal SSwRs and SVmRs did not correlate with results of nerve conduction studies. Conclusions Skin sudomotor or vasomotor sympathetic function is frequently impaired in CTS. Susceptibility to compression ischemia may be different in sympathetic unmyelinated and large myelinated fibers.

Neural Control of Motion-to-Force Transitions with the Fingertip

The neural control of tasks such as rapid acquisition of precision pinch remains unknown. Therefore, we investigated the neural control of finger musculature when the index fingertip abruptly transitions from motion to static force production. Nine subjects produced a downward tapping motion followed by vertical fingertip force against a rigid surface. We simultaneously recorded three-dimensional fingertip force, plus the complete muscle coordination pattern using intramuscular electromyograms from all seven index finger muscles. We found that the muscle coordination pattern clearly switched from that for motion to that for isometric force approximately 65 ms before contact (p = 0.0004). Mathematical modeling and analysis revealed that the underlying neural control also switched between mutually incompatible strategies in a time-critical manner. Importantly, this abrupt switch in underlying neural control polluted fingertip force vector direction beyond what is explained by muscle activation-contraction dynamics and neuromuscular noise (p < or = 0.003). We further ruled out an impedance control strategy in a separate test showing no systematic change in initial force magnitude for catch trials where the tapping surface was surreptitiously lowered and raised (p = 0.93). We conclude that the nervous system predictively switches between mutually incompatible neural control strategies to bridge the abrupt transition in mechanical constraints between motion and static force. Moreover because the nervous system cannot switch between control strategies instantaneously or exactly, there arise physical limits to the accuracy of force production on contact. The need for such a neurally demanding and time-critical strategy for routine motion-to-force transitions with the fingertip may explain the existence of specialized neural circuits for the human hand.

Neural correlates of simple unimanual discrete and continuous movements: a functional imaging study at 3 T

The cerebral and cerebellar network involved in unimanual continuous and discrete movements was studied in blood oxygenation level-dependent functional magnetic resonance imaging (fMRI) at 3 T. Seven healthy right-handed volunteers were scanned (1) while drawing a circle with the tip of the right index finger (continuous motor task), and (2) while drawing a triangle with the tip of the right index finger (discrete motor task). In both motor tasks, extensive activations were observed in the sensorimotor (M1/S1), parietal, prefrontal, insular, lateral occipital (LOC) and anterior cerebellar cortices. Subcortical activations within red, thalamic and lentiform nuclei were also detected. However, discrete movements were specifically followed by the recruitment of the left orbitofrontal cortex, right dentate nucleus and the second cerebellar homunculus (HVIII), and bilateral and stronger activation of the sensorimotor cortical areas, whereas continuous movements specifically activated the right prefrontal cortex and the lateral hemispherical part of the neocerebellum (crus 1). We confirm the findings of previous studies showing partly distinct neural networks involved in monitoring continuous and discrete movements, but we found new differential neural relays within the prefrontal, insular and neocerebellar cortices.

A Study on the Friction Characteristics of Human Finger Pulp

We developed an experimental device to measure the coefficient of friction of human finger pulp and investigated the influence of three factors (angle of contact with the friction surface, moisture condition of the fingertip, and roughness of the friction surface) on the coefficient of friction. Ten male subjects who had no hand injuries (average age : 23.8 years) were selected. Each subject was instructed to touch the friction plate (acryl plate) using the right index fingertip while applying a vertical force of approximately 20 N and then to slide the right index fingertip at a speed of approximately 5 mm/s. The angle of contact with the friction surface was defined as the angle between the central axis of the finger and the friction plate, and was set to 30, 45, and 60 degrees. In order to investigate the influence of the moisture condition, artificial sweat was applied to the fingertip to simulate three conditions (dry, appropriate moisture, and excess moisture conditions). In order to investigate the influence of the roughness of the friction surface, four aluminum plates processed by straight knurling under different conditions were used as friction plates to produce different surface roughnesses. The maximum coefficient of friction at the start of finger sliding was taken as the maximum coefficient of static friction μs, while the average coefficient of friction during sliding was taken as the coefficient of dynamic friction μk of the subject. As the angle of contact increased, μs and, μs tended to decrease, and μs at an angle of contact of 30 degrees was significantly greater than that at 60 degrees. No significant difference was observed for μk. With respect to the influence of the moisture condition, μk for the appropriate moisture condition was significantly greater than that for the dry condition. In addition, μk for the excess moisture condition did not differ from that for the dry condition. In the case of μs, there was no significant difference between the three conditions. With respect to the influence of the roughness of the friction surface, as the surface roughness increased, μs increased, and when the surface roughness exceeded a certain fixed level, it did not affect μs or μk.

A case of mixed connective tissue disease presenting initially with Raynaud's phenomenon

= Abstract = Mixed connective tissue disease (MCTD) is characterized by diverse symptoms including rheumatoid arthritis, scleroderma, systemic lupus erythematosus, and dermatomyositis, associated with high titers of antibodies to extractable nuclear antigen (ENA), especially anti-ribonucleoprotein (anti-RNP) antibody. Since the first report of 25 cases with MCTD in adults, there have been only a few cases of MCTD reported in children. Here, we report a rare childhood case of MCTD in a 7-year-old girl presenting initially with Raynaud's phenomenon, swollen hands, and ulceration of the right index finger tip followed by alopecia and arthritis during follow-up. (Korean J Pediatr 2008;51:886-891)

RATIO OF FOURTH TO SECOND FINGERTIP EXTENSIONS IN RELATION TO SERUM ESTRADIOL AND TESTOSTERONE LEVELS IN MEN AND WOMEN

-Sex differences in second (2D) and fourth (4D) fingertip extensions relative to the middle fingertip and 4D:2D fingertip extension ratios were studied in men and women. Body height positively correlated with index fingertip extensions, not with ring fingertip extensions, nor with their ratio. Mean 2D extension (both hands) was smaller in women than men; mean 4D extension (right hand) was smaller in men than women; 4D:2D fingertip extension ratios from both hands were larger in women than men. Serum estradiol concentration negatively correlated with 2D extensions for both hands (no significant correlation with 4D extensions), but positively correlated with 4D:2D extension ratios for both hands. Serum testosterone concentration positively correlated with 2D extensions of both hands (no significant correlation with 4D extension), but negatively correlated with 4D:2D extension ratios for both hands. These relations were also studied in men and women separately. It was concluded that the 4D:2D extension ratio was greater in women than in men; 2D and 4D extensions and 4D:2D extension ratios may be determined prenatally by sex hormones; fingertip extensions may be predictive of adult and prenatal sex hormone levels.

Mechanical and focal electrical stimuli applied to the skin of the index fingertip induce both inhibition and excitation in low‐threshold flexor carpi radialismotor units

It has been observed that mechanical stimulation of the skin of the index fingertip causes a weak short-latency inhibition followed by a strong long-lasting facilitation of the flexor carpi radialis (FCR) H-reflex. Based on threshold and latency, these cutaneous reflexes are thought to be routed to motoneurons by parallel pathways. As recent studies have shown predominant inhibitory potentials in slow motoneurons and predominant excitatory potentials in faster ones, the question arises as to whether or not the two cutaneous pathways converge onto the same motoneuron. The poststimulus time histogram technique was used to investigate the changes in firing frequency of low-threshold FCR motor units (MUs), induced by passive mechanical or focal electrical stimuli to the index skin. After gently tapping the finger pulp a small sharp inhibition appeared in 20 MUs. On average, inhibition started 10.2 +/- 1.6 ms from the homonymous Ia monosynaptic effect, and its central delay was estimated to be 1.2 +/- 1.6 ms. The subsequent facilitation, more consistent, had a mean latency of 13.5 +/- 1.7 ms. Inhibition and excitation were statistically significant (P < 0.05). A similar biphasic effect was observed in seven other FCR-MUs, also after focal electrical stimulation of the same skin area. Comparison with the time course of the H-reflex, representing the whole population of MUs, showed striking similarities in time course and latency to the present MU effect. It is thus suggested that cutaneous spinal pathways may have a homogeneous distribution within the FCR motoneuron pool, and that the skewed distribution of cutaneous afferents onto motoneurons should be not taken as a rule.