Axonal regrowth is impaired during digit tip regeneration in mice

Mice are intrinsically capable of regenerating the tips of their digits after amputation. Mouse digit tip regeneration is reported to be a peripheral nerve-dependent event. However, it is presently unknown what types of nerves and Schwann cells innervate the digit tip, and to what extent these cells regenerate in association with the regenerative response. Given the necessity of peripheral nerves for mammalian regeneration, we investigated the neuroanatomy of the unamputated, regenerating, and regenerated mouse digit tip. Using immunohistochemistry for β-III-tubulin (β3T) or neurofilament H (NFH), substance P (SP), tyrosine hydroxylase (TH), myelin protein zero (P0), and glial fibrillary acidic protein (GFAP), we identified peripheral nerve axons (sensory and sympathetic), and myelinating- and non-myelinating-Schwann cells. Our findings show that the digit tip is innervated by two digital nerves that each bifurcate into a bone marrow (BM) and connective tissue (CT) branch. The BM branches are composed of sympathetic axons that are ensheathed by non-myelinating-Schwann cells whereas the CT branches are composed of sensory and sympathetic axons and are ensheathed by myelinating- and non-myelinating-Schwann cells. The regenerated digit neuroanatomy differs from unamputated digit in several key ways. First, there is 7.5 fold decrease in CT branch axons in the regenerated digit compared to the unampuated digit. Second, there is a 5.6 fold decrease in myelinating-Schwann cells in the regenerated digit compared to the unamputated digit that is consistent with the decrease in CT branch axons. Importantly, we also find that the central portion of the regenerating digit blastema is aneural, with axons and Schwann cells restricted to peripheral and distal blastema regions. Finally, we show that even with impaired innervation, digits maintain the ability to regenerate after re-amputation. Taken together, these data indicate that nerve regeneration is impaired in the context of mouse digit tip regeneration.

Utilizing the Ipswich Touch Test to simplify screening methods for identifying the risk of foot ulceration among diabetics: The Saudi experience

Our study demonstrates that Ipswich Touch Test is reliable and comparable to established standardized tests that identify the risk of foot ulceration among Saudi patients with diabetes mellitus. The simplicity of the test will assist in overcoming the barriers to screen for and detect the risk of foot ulceration.

Hyposensitivity of C-fiber afferents at the distal extremities as an indicator of early stages diabetic bladder dysfunction in type 2 diabetic women

Purpose

To investigate the relationship between distal symmetric peripheral neuropathy and early stages of autonomic bladder dysfunction in type 2 diabetic women.

Materials and Methods

A total of 137 diabetic women with minimal coexisting confounders of voiding dysfunction followed at a diabetes clinic were subject to the following evaluations: current perception threshold (CPT) tests on myelinated and unmyelinated nerves at the big toe for peroneal nerve and middle finger for median nerve, uroflowmetry, post-void residual urine volume, and overactive bladder (OAB) symptom score questionnaire. Patients presenting with voiding difficulty also underwent urodynamic studies and intravesical CPT tests.

Results

Based on the OAB symptom score and urodynamic studies, 19% of diabetic women had the OAB syndrome while 24.8% had unrecognized urodynamic bladder dysfunction (UBD). The OAB group had a significantly greater mean 5 Hz CPT test value at the big toe by comparison to those without OAB. When compared to diabetic women without UBD, those with UBD showed greater mean 5 Hz CPT test values at the middle finger and big toe. The diabetic women categorized as C-fiber hyposensitivity at the middle finger or big toe by using CPT test also had higher odds ratios of UBD. Among diabetic women with UBD, the 5 Hz CPT test values at the big toe and middle finger were significantly associated with intravesical 5 Hz CPT test values.

Conclusions

Using electrophysiological evidence, our study revealed that hyposensitivity of unmyelinated C fiber afferents at the distal extremities is an indicator of early stages diabetic bladder dysfunction in type 2 diabetic women. The C fiber dysfunction at the distal extremities seems concurrent with vesical C-fiber neuropathy and may be a sentinel for developing early diabetic bladder dysfunction among female patients.

Monofilament insensitivity and small and large nerve fiber symptoms in impaired fasting glucose

AIMS

To determine if diabetes or pre-diabetes is associated with monofilament insensitivity and peripheral neuropathy symptoms.

METHODS

The 10-g Semmes-Weinstein monofilament test and Michigan Neuropathy Screening Instrument symptom questionnaire were administered to participants in the Study of Women's Health Across the Nation - Michigan site (n=396). We determined the concordance of monofilament insensitivity and symptoms and used chi-square tests, ANOVA, and logistic regression to quantify the relationships among diabetes status, monofilament insensitivity and symptoms.

RESULTS

The prevalence of monofilament insensitivity was 14.3% and 19.4% of women reported symptoms of peripheral neuropathy. With monofilament testing, 11.7% of women with normal fasting glucose, 14.4% of women with impaired fasting glucose (IFG) and 18.3% of women with diabetes had monofilament insensitivity (p-value=0.33). For symptoms, 14.0% of women with normal fasting glucose, 16.5% of women with IFG and 31.2% of women with diabetes reported symptoms of peripheral neuropathy. Women who reported symptoms of small fiber nerve dysfunction alone were unlikely to have monofilament insensitivity. Compared to women with normal fasting glucose, women with diabetes were more likely to report peripheral neuropathy symptoms [OR 2.8 (95% CI: 1.5, 5.1)]. Women with diabetes were also more likely to report symptoms than women with IFG (p=0.02). There was no difference in the frequency of symptoms between women with normal fasting glucose and IFG.

CONCLUSIONS

Women with diabetes were more likely to report peripheral neuropathy symptoms. The prevalence of monofilament insensitivity and peripheral neuropathy symptoms did not differ between women with normal fasting glucose and IFG.

Computed tomography analysis of third webspace injections for interdigital neuroma

BACKGROUND

Injection for interdigital neuroma (IDN) may not selectively target the common digital nerve. We investigated the anatomical localization and extent of extravasation with injection for IDN.

METHODS

Two fellowship-trained foot and ankle surgeons injected radiopaque contrast into the third webspace of 49 cadaveric specimens (29 with 2 mL and 20 with 1 mL). Computed tomography scan of each specimen was obtained. An independent blinded foot and ankle surgeon analyzed the scans.

RESULTS

All injections were accurate. Contrast was found in the second (greater than 70%) and fourth (greater than 30%) webspaces in both injection volume groups. No contrast was found within the third metatarsophalangeal joint. Extravasation extent was significantly greater with 2 mL versus 1 mL of solution in the medial to lateral (27.9 [7.8] mm vs 23.7 [6.0] mm; P = .05) and distal to proximal (52.1 [13.7] mm vs 40.4 [16.1] mm; P = .01) planes. No differences were observed in extravasation extent between surgeons.

CONCLUSION

Injection for IDN was accurate, and extravasation extended into adjacent webspaces in a large percentage of specimens with both solution volumes. Lower extent of extravasation with 1 mL of solution did not indicate better selectivity of injection.

CLINICAL RELEVANCE

Steroid injections for interdigital neuroma were accurate for therapeutic purposes but not diagnostic, except potentially for distinguishing webspace pain from joint pain.

TOE-TO-HAND TRANSFER IN SYMBRACHYDACTYLY

Symbrachydactyly, or central atypical cleft, is classified as a failure of formation. For the adactylous or monodactylous forms, free toe transfer is the treatment of choice. We present 18 free toe transfers in 13 patients for symbrachydactyly. Despite abnormal anatomy, the functional building blocks have always been available and transfer technically possible. The result has been improved function and high levels of parental satisfaction.

Dorsal versus ventral monofilament testing of the great toe for the identification of diabetic sensorimotor polyneuropathy

We tested whether monofilament examination of the ventral rather than dorsal aspect of the great toe could better detect diabetic sensorimotor polyneuropathy (DSP). Although dorsal testing had better overall performance for identifying Subclinical DSP, the magnitude of benefit was small and there was no difference in identifying Clinical DSP.

Case reports: Painful limbs/moving extremities: report of two cases

BACKGROUND

Painful limbs/moving extremities is a relatively rare condition characterized by aching pain in one limb and involuntary movement in the affected fingers or toes. Its pathomechanism is unknown. We report two patients with painful limbs/moving extremities. In one patient with a painful arm and moving fingers, the symptoms were resolved after surgery.

CASE DESCRIPTIONS

Patient 1 was a 36-year-old man with a painful arm and moving fingers. Treatment with administration of analgesics was not effective. Postmyelographic CT showed stenosis of the right C5/C6 foramen attributable to cervical spondylosis and a defect of the contrast material at the foramen. He was treated with cervical foraminotomy. Patient 2 was a 26-year-old woman with a painful leg and moving toes. The pain and involuntary movement appeared 2 weeks after discectomy at L5/S1. Lumbar MRI and myelography showed no indications of nerve root compression. She was treated with a lumbar nerve root block. The pain and involuntary movement completely disappeared in both patients after treatment.

LITERATURE REVIEW

Numerous studies report treatments for painful limbs/moving extremities, but few report successful treatment. Recently, botulinum toxin A injection and epidural spinal cord stimulation have been used and are thought to benefit this condition. Successful surgical treatment previously was reported for only one patient.

PURPOSES AND CLINICAL RELEVANCE

If imaging indicates compression of nerve tissue, we believe surgical decompression should be considered for patients with painful limbs/moving extremities who do not respond to nonoperative treatment.

The innervation of extensor hallucis longus muscle: an anatomical study for selective neurotomy

OBJECTIVE

This study is aimed to describe the observable anatomical variants of the innervation of extensor hallucis longus muscle (EHLM) in order to have the surgical coordinates to perform neurotomy on the targeted branches of its innervation and to give a valuable alternative to the commonly used technique of fascicular subepineurial neurotomy in patients affected by toe hyperextension dystonia.

METHODS

In 15 fresh cadavers of adults, 29 lower limbs (14 right and 15 left) were studied. Anatomical dissections to isolate the innervating branches of EHLM were performed. Each branch from EHLM was analyzed by microscopical opening of the epineurium to observe the number of nerve fascicles. Various measurements were made to obtain anatomical coordinates for surgery.

RESULTS

The distance between the most prominent point of the head of the fibula and the origin of the nervous branches innervating the EHLM is not proportional to the length of the leg. In 72.4% of the studied legs, the distance between the origin of the first branch innervating the EHLM and the origin of the deep peroneal nerve is 7 +/- 2 cm. In 80% of legs, the distance between the origin of the second branch and the origin of the deep peroneal nerve is 10 +/- 1.1 cm. In only one limb with double innervation, two fascicles were found, while in six limbs (25%) only one fascicle was found.

CONCLUSIONS

This anatomical study traced some valuable surgical coordinates useful for the execution of a selective peripheral neurotomy on the nerve branch innervating the EHLM.

AGILITY, GNOSIS, AND GRAPHAESTHESIA FOR THE TOES AND FINGERS IN CHILDREN: NORMATIVE DATA (AGES 7-14 YEARS)

The differential representation of the toes/feet and fingers/hands along the medial and lateral surfaces of the cerebral cortices, respectively, may have diagnostic utility. Normative data for errors for toe and finger graphaesthesia and gnosis, as well as foot and finger agility, were collected for 86 children (ages 7 to 14). The fingers were more agile than the feet, and the right side of the body was more agile than the left side, regardless of age. A marked improvement in toe gnosis, but not in finger gnosis occurred in children after 11-12 years of age. A statistically significant interaction between laterality and gender was due to the greater numbers of errors for both toe and finger gnosis, displayed by girls for the left sides of their bodies compared to their right sides. This discrepancy was not significant for boys.

The Neuropad test: a visual indicator test for human diabetic neuropathy

AIMS/HYPOTHESIS

The commercially available Neuropad test was developed as a simple visual indicator test to evaluate diabetic neuropathy. It uses a colour change to define the integrity of skin sympathetic cholinergic innervation. We compared the results of Neuropad assessment in the foot with established measures of somatic and autonomic neuropathy.

METHODS

Fifty-seven diabetic patients underwent Neuropad assessment, quantitative sensory and autonomic function testing, and evaluation of intra-epidermal nerve fibre density in foot skin biopsies.

RESULTS

Neuropad responses correlated with the neuropathy disability score (r(s)=0.450, p<0.001), neuropathic symptom score (r(s)=0.288, p=0.03), cold detection threshold (r(s)=0.394, p = 0.003), heat-as-pain perception threshold visual analogue score 0.5 (r(s)=0.279, p=0.043) and deep-breathing heart rate variability (r(s)= -0.525, p<0.001). Intra-epidermal nerve fibre density (fibres/mm) compared with age- and sex-matched control subjects (11.06+/-0.82) was non-significantly reduced (7.37+/-0.93) in diabetic patients with a normal Neuropad response and significantly reduced in patients with a patchy (5.01+/-0.93) or absent (5.02+/-0.77) response (p=0.02). The sensitivity of an abnormal Neuropad response in detecting clinical neuropathy (neuropathy disability score >or=5) was 85% (negative predictive value 71%) and the specificity was 45% (positive predictive value 69%).

CONCLUSIONS/INTERPRETATION

The Neuropad test may be a simple indicator for screening patients with diabetic neuropathy.

Painful limbs/moving extremities

Painful limbs/moving extremities (PLME) is a disorder characterized by spontaneous, complex, slow (1-2 Hz) involuntary toe or finger movements. The movements that can be bilateral or unilateral are usually accompanied by pain in the affected limbs. Painless variants are less common. PLME has been associated with peripheral and central nervous system disease although idiopathic cases have been reported. Its etiopathogenesis is unknown and treatment approaches remain largely empirical. Nerve blocks and botulinum toxin type A injections as well as oral medication have had some measure of success. Current theories suggest that central oscillator(s) at the spinal or supraspinal levels may be involved. Future research in PLME should include prospective electrophysiological and functional imaging studies as well as clinical trials with botulinum toxin injections and oral pharmacological agents.

High doses of botulinum toxin effectively treat disabling up-going toe

Involuntary up-going toe can be a disabling consequence of dystonia or spasticity. In this study, we treated eight patients with botulinum toxin (BTx) in the extensor hallucis longus (EHL) and applied objective and subjective outcome measures to determine treatment efficacy. Using 100% higher doses than generally reported, patients noted 62+/-20% mean benefit and scores on a modified Fahn-Marsden Dystonia Scale decreased significantly by 1.8+/-0.6 (p=0.010). High doses (up to 160 BTx A units) into the EHL were safe and dosage correlated highly and significantly with treatment efficacy (rho=0.859, p=0.006).

[Filippo Civinini (1805-1844) and the discovery of plantar neuroma]

Pathological abnormality (neuroma) related to the painful foot condition commonly called "Morton's metatarsalgia" was first observed in 1835 by Filippo Civinini (1805-1844) of Pistoia, in course of a cadaverous dissection, and clearly described in the anatomic letter entitled "Su un nervoso gangliare rigonfiamento alla pianta del piede" ("On the neural ganglion swelling of the foot sole"). In this study a brief review on the history of Morton's metatarsalgia is carried out, and the importance of Civinini in the discovery of the neuroma of the III intermetatarsal web is underlined.

The tibial second toe vascularized neurocutaneous free flap for major digital nerve defects

PURPOSE

Most digital nerve defects can be reconstructed by means of nonvascularized nerve grafts or artificial tubes, for example. When the bed is poor, the defect is long, or there is a concomitant soft-tissue loss; however, a vascularized nerve graft may be a better option. Our purpose is to introduce a method of 1-stage reconstruction of complex neurocutaneous defects in the fingers and to report the results and clinical effectiveness at a minimum 1-year follow-up period.

METHODS

From 1997 to 2005 there were 6 consecutive patients who had a combined soft-tissue and digital nerve defect reconstructed by a vascularized neurocutaneous flap from the tibial (medial) side of the second toe. Three were acute and 3 were chronic cases. One flap was used for the ulnar side of the thumb, 2 for the radial aspect of the index finger, 1 for the radial of the small finger, and 2 for the ulnar side of the small finger. The nerve gap averaged 4.2 cm, and the flap size averaged 3.2 x 2.1 cm. The flaps were revascularized with standard microsurgical techniques to local vessels in the fingers. The nerves were sutured with epineural stitches. A split-thickness skin graft was used to close the donor site of the toe.

RESULTS

All flaps survived without complications. At the latest follow-up evaluation static two-point discrimination (s2PD) averaged 8 mm on the pulp. Three patients had normal sensation when tested with Semmes-Weinstein filaments. Subjective feeling was 78% of that of the normal side. Five patients rated their feeling as excellent on a subjective scale. The Disabilities of the Arm, Shoulder, and Hand questionnaire score averaged 5.

CONCLUSIONS

The tibial neurocutaneous second toe free flap is suitable for reconstructing a missing nerve and soft-tissue defect in the finger. We found good functional recovery and high satisfaction in this group of patients. The donor site morbidity has been minimal, although delayed healing is common.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

The frequency of digital artery resection in Morton interdigital neurectomy

BACKGROUND

Operative strategies used in resecting the digital nerve in Morton neuroma emphasize retaining the digital artery. Concern over inadvertent resection of the digital vessel has prompted many surgeons to avoid adjacent interdigital neurectomies when more than one nerve is affected.

METHODS

The current study examined 674 consecutive pathologic specimens obtained after neurectomy.

RESULTS

The digital vessel was identified along with the resected nerve in 39% of specimens. No adverse effect was recorded from these arterial resections.

CONCLUSION

Extensive collateralization of digital vessels is hypothesized to account for the lack of adverse sequelae.

Functional MR imaging of the human sensorimotor cortex after toe-to-finger transplantation

BACKGROUND

A model of toe-to-finger transplantation has been used in studying peripheral nerve regeneration and central reorganization. It was found that recovery of sensory perception depends not only on peripheral reinnervation but also on central integrative mechanisms.

OBJECTIVE

Our aim was to investigate functional changes of the brain and somatotopic representation of the transplanted toes after toe-to-finger transplantation.

MATERIALS AND METHODS

Six patients who had toe-to-finger transplantation from 3 to 8 years earlier underwent motor and sensory functional MR imaging studies of transplanted toes and opposite corresponding normal fingers. The motor task was performed by repetitively tapping of the transplanted toe or finger against the thumb, whereas the sensory task was applied by tactilely stimulating the pulp of the transplanted toe or finger.

RESULTS

The main activation areas from both types of stimulations were located in the expected location of the finger homunculus of the primary sensorimotor cortex. In addition, activated volumes from the transplanted toes were significantly greater than those from the opposite fingers (P = .017 for motor task and P = .005 for tactile sensory task, paired samples Student t test).

CONCLUSIONS

Functional recruitment in the primary sensorimotor cortex seemed to have occurred following toe-to-finger transplantation. The transplanted toe was somatotopically represented in the hand area.

Location specificity of plantar cutaneous reflexes involving lower limb muscles in humans

It is known that cutaneous reflexes in human hand muscles show strong location-specificity dependent on the digit stimulated. We hypothesized that in lower leg muscles the cutaneous reflex following tactile sensation of the plantar surface of the foot is also organized in a location-specific manner. The purpose of the present study was to test this hypothesis. Middle latency reflexes (approximately 70-110 ms, MLR) following non-noxious electrical stimulation to different locations on the plantar foot were recorded from 16 neurologically intact volunteers (15 males, 1 female). Electrical stimulation was given to the fore-medial (f-M), fore-lateral (f-L) and heel (HL) regions of the plantar surface of the right foot while the subjects performed isometric dorsiflexion (tibialis anterior, TA), plantarflexion (soleus, Sol and medial gastrocnemius, MG), eversion (peroneus longus, PL) and knee extension (vastus lateralis, VL) while sitting and standing. In the Sol and MG, an excitatory response was observed following HL stimulation, which was switched to an inhibitory response following f-M or f-L stimulation (P < 0.001). A reciprocal pattern in contrast to Sol was observed in the TA. In the PL, MLR exhibited significant excitation following both f-L and HL stimulation, which, however, was switched to an inhibitory response following f-M stimulation (P < 0.001). Moderate inhibition of the MLR was seen in the VL for all stimulated positions. Systematic stimulation along the lateral side of the plantar foot demonstrated that the reflex reversal occurred around the middle of the plantar foot in the Sol and TA. In all muscles tested, the slope of the regression line between the magnitude of the MLR and background electromyographic activity significantly decreased during standing compared with sitting except for the PL following f-L simulation. These results suggest that reflex effects from cutaneous nerves in the plantar foot onto the motoneurons innervating the lower leg muscles are organized in a highly topographic manner in humans. The organization of these reflexes may play an important role in the alteration of limb loading and/or ground contact in response to tactile sensation of the plantar foot while sitting and standing.

Estimations of topographically correct regeneration to nerve branches and skin after peripheral nerve injury and repair

Peripheral nerve injury is typically associated with long-term disturbances in sensory localization, despite nerve repair and regeneration. Here, we investigate the extent of correct reinnervation by back-labeling neuronal soma with fluorescent tracers applied in the target area before and after sciatic nerve injury and repair in the rat. The subpopulations of sensory or motor neurons that had regenerated their axons to either the tibial branch or the skin of the third hindlimb digit were calculated from the number of cell bodies labeled by the first and/or second tracer. Compared to the normal control side, 81% of the sensory and 66% of the motor tibial nerve cells regenerated their axons back to this nerve, while 22% of the afferent cells from the third digit reinnervated this digit. Corresponding percentages based on quantification of the surviving population on the experimental side showed 91%, 87%, and 56%, respectively. The results show that nerve injury followed by nerve repair by epineurial suture results in a high but variable amount of topographically correct regeneration, and that proportionally more neurons regenerate into the correct proximal nerve branch than into the correct innervation territory in the skin.

Tibial nerve motor conduction with recording from the first dorsal interosseous: a comparison with standard tibial studies

PURPOSE

The lateral plantar nerve (LPN) branch of the tibial nerve provides the primary supply to the first dorsal interosseous (FDI) muscle of the foot. A consistent clear response has been observed with recording of the LPN from the FDI muscle. This clarity is not always found with the standard recording site for the LPN. As there are no published normative values for the FDI recording site, the purpose of this study is to describe these values and compare them with standard tibial values.

METHODS

Fifty four healthy adult volunteers with 102 limbs were studied to determine the nerve conduction velocity, distal latency, amplitude, and waveform characteristics.

RESULTS

The FDI recording demonstrated a significantly greater amplitude than did the standard recording, with the mean values being 7.7 and 3.6 mV respectively. The recording from the FDI also demonstrated much greater waveform clarity than did the standard tibial nerve recordings.

CONCLUSIONS

These findings may aid interpretation of data collected from the FDI in tibial nerve testing. LPN recording from the FDI may be particularly valuable in those with global axonal loss or preferential involvement of the LPN as may occur in posterior tarsal tunnel syndrome.

Stepping over an obstacle on a compliant travel surface reveals adaptive and maladaptive changes in locomotion patterns

Adaptive human locomotion is dependent on safe clearance of obstacles encountered in the path of locomotion. When the terrain is uneven or compliant, stability along with safe obstacle clearance are competing demands presented to the central nervous system (CNS). To examine how the CNS deals with the two competing demands, six participants walked under four conditions: normal ground walking, normal ground walking with an obstacle in the travel path, compliant surface walking, and compliant surface walking with an obstacle in the travel path. Full body kinematics were measured and swing limb kinetics were derived from these measurements. Results showed that on a compliant surface, the CNS was able to decrease foot placement variability at foot contact when approaching an obstacle, similar to the normal ground terrain. Limb trajectory over the obstacle showed that toe elevation was maintained while clearance over the obstacle was lower in the compliant surface condition due to depression of the surface during push off. This illustrates that the CNS controls toe elevation, not toe clearance when stepping over an obstacle. Work done in the knee during elevation and hip during lowering was similar in the compliant and ground conditions even though a lower clearance over the obstacle was achieved in the complaint condition. This shows the inability of the CNS to account for compression of the surface prior to obstacle clearance and provides further evidence the CNS controls toe elevation, not clearance when stepping over an obstacle.

Peripheral neuropathies in Waldenström's macroglobulinaemia

OBJECTIVE

We sought to determine the prevalence, clinical features, and laboratory characteristics of polyneuropathies in Waldenström's macroglobulinaemia (WM), a malignant bone marrow disorder with lymphocytes that produce monoclonal IgM.

METHODS

We prospectively studied 119 patients with WM and 58 controls. Medical history was taken, and neurological examinations, electrodiagnostic tests, and serum studies were performed by different examiners who were blinded to results except the diagnosis of WM.

RESULTS

Polyneuropathy symptoms, including discomfort and sensory loss in the legs, occurred more frequently (p<0.001) in patients with WM (47%) than in controls (9%). Patients with WM had 35% lower quantitative vibration scores, and more frequent pin loss (3.4 times) and gait disorders (5.5 times) than controls (all p<0.001). Patients with IgM binding to sulphatide (5% of WM) had sensory axon loss; those with IgM binding to myelin associated glycoprotein (MAG) (4% of WM) had sensorimotor axon loss and demyelination. Patients with WM with IgM binding to sulphatide (p<0.005) or MAG (p<0.001) had more severe sensory axon loss than other patients with WM. Demyelination occurred in 4% of patients with WM with no IgM binding to MAG. Age related reductions in vibration sense and sural SNAP amplitudes were similar ( approximately 30%) in WM and controls.

CONCLUSIONS

Peripheral nerve symptoms and signs occur more frequently in patients with WM than controls, involve sensory modalities, and are often associated with gait disorders. IgM binding to MAG or sulphatide is associated with a further increase in the frequency and severity of peripheral nerve involvement. Age related changes, similar to those in controls, add to the degree of reduced nerve function in patients with WM.

Anatomical study of the communicating branches between the medial and lateral plantar nerves

The plantar areas of the foot have specific biomechanical characteristics and play a distinct role in balance and standing. For the forefoot surgeon, knowledge of the variations in the anatomy of communicating branches is important for plantar reconstruction, local injection therapy and an excision of interdigital neuroma. The anatomy of the communicating branches of the plantar nerves between the fourth and third common plantar digital nerves in the foot were studied in 50 adult men cadaveric feet. A communicating branch was present between the third and fourth intermetatarsal spaces nerves in all eight left feet and in six right feet (overall, 28%), and absent in 36 (72%). A communicating branch was found in 14 ft. Ten of the 14 communications were from the lateral to the medial plantar nerve. The length of the communicating branch ranged from 8 to 56 mm (average 16.4 mm) and its diameter was 0.2-0.6 times of the fourth common plantar digital nerve. The angle of the communicating branch with the common plantar digital nerve from which it originated was less than 30 degrees in 11 ft, 30-59 degrees in 27 ft, 60-80 degrees in 8 ft, and more than 80 degrees in 4 ft. Classification of the branch is based on the branching pattern of the communicating branch and explains variations in plantar sensory innervations. We think that the perpendicular coursing communicating branch is at higher risk to be severed during surgery.

Incongruent restoration of inhibitory transmission and general metabolic activity during reorganization of somatosensory cortex

Activity markers cytochrome oxidase (CO) and glutamic acid decarboxylase (GAD) were analyzed in the primary somatosensory cortex of raccoons that underwent digit amputation. Subjects recovered for 2, 15, and 23 weeks following amputation of the fourth forepaw digit. Histochemistry was used to assess relative activity levels of both enzymes. We found a pronounced decrease in the numbers of CO intense patches in the cortical gyrus that had lost its original sensory input from the fourth digit. This decrease in CO activity was still apparent 15 weeks post-amputation. Conversely, no clear decrease in GAD levels could be identified in connection with the amputation procedure. Our findings present evidence that a significant decrease in metabolic activity results from the loss of the primary afferent sensory drive. The remaining GAD activity suggests that the absence of electrical activity, characteristic of reorganizing cortex, is likely to depend in part on lateral inhibitory cortical connections.

What happens to the readiness potential when the movement is not executed?

The purpose of this study was to investigate and compare the movement-related brain potentials recorded from two groups of right-handed male study participants. One of the groups prepared for and conducted repetitive toe movements while the other prepared to carry out the same type of movement but finally did not execute it. The readiness potential, premotion positivity, motor potential and reafferent potential were recorded from 20 electroencephalogram electrodes. The most salient result was the greater readiness potential amplitude discovered in participants who ended up carrying out the movement, which indicates that the level of preparation in a repetitive task is greater when a final response is required. No group differences were found for the other potentials.

Cortical Plasticity Following Upper Extremity Injury and Reconstruction

Today's view of the adult central nervous system is that of an adaptive and responsive system. Plastic surgeons, because of the motor and sensory reconstructions they perform, need to have an understanding of brain plasticity following upper extremity injury, reconstruction, and rehabilitation. Functional MRI and transcranial magnetic stimulation can identify cortical plasticity in humans. For instance, these techniques have identified changes in excitability and body site representation in the motor cortex in patients following motor reconstruction and motor relearning. Therefore, cortical plasticity and its manipulation may be an important contributor to functional outcome following reconstruction. In the future, cortical plasticity may have implications for reconstruction and rehabilitation.

Oxidized galectin-1 advances the functional recovery after peripheral nerve injury

Oxidized galectin-1 has been shown to promote axonal regeneration from transected-nerve sites in an in vitro dorsal root ganglion (DRG) explant model as well as in in vivo peripheral nerve axotomy models. The present study provides evidence that oxidized galectin-1 advances the restoration of nerve function after peripheral nerve injury. The sciatic nerve of adult rats was transected and the distal nerve was frozen after being sutured into a proximal site with four epineurial stitches. An osmotic pump delivered oxidized galectin-1 peripherally to the surgical site. Functional recovery was assessed by measurement of the degree of toe spread of the hind paw for 3 months after the sciatic nerve lesion. The recovery curves of toe spread in the test group showed a statistically significant improvement of functional recovery after day 21 by the application of oxidized recombinant human galectin-1 (rhGAL-1/Ox) compared to the control group. This functional recovery was supported by histological analysis performed by light microscopic examination. The regenerating myelinated fibers at the site 21 mm distal to the nerve-transected site were quantitatively examined at 100 days after the operation. The frequency distribution of myelinated fiber diameters showed that exogenous rhGAL-1/Ox increased the number and diameter of regenerating myelinated fibers; the number of medium-sized (6-11 microm in diameter) fibers increased significantly (P<0.05). These results indicate that oxidized galectin-1 promotes the restoration of nerve function after peripheral nerve injury. Thus, rhGAL-1/Ox may be a factor for functional restoration of injured peripheral nerves.

Difference in somatosensory evoked fields elicited by mechanical and electrical stimulations: Elucidation of the human homunculus by a noninvasive method

We recently recorded somatosensory evoked fields (SEFs) elicited by compressing the glabrous skin of the finger and decompressing it by using a photosensor trigger. In that study, the equivalent current dipoles (ECDs) for these evoked fields appeared to be physiologically similar to the ECDs of P30m in median nerve stimulation. We sought to determine the relations of evoked fields elicited by mechanically stimulating the glabrous skin of the great toe and those of electrically produced P40m. We studied SEFs elicited by mechanical and electrical stimulations from the median and tibial nerves. The orientations of dipoles from the mechanical stimulations were from anterior-to-posterior, similar to the orientations of dipoles for P30m. The direction of the dipole around the peak of N20m from median nerve electrical stimulation was opposite to these directions. The orientations of dipoles around the peak of P40m by tibial nerve stimulation were transverse, whereas those by the compression and decompression stimulation of the toe were directed from anterior-to-posterior. The concordance of the orientations in ECDs for evoked fields elicited by mechanical and electrical stimulations suggests that the ECDs of P40m are physiologically similar to those of P30m but not to those of N20m. The discrepancy in orientations in ECDs for evoked field elicited by these stimulations in the lower extremity suggests that electrical and compression stimulations elicit evoked fields responding to fast surface rubbing stimuli and/or stimuli to the muscle and joint.

Right-left correlation of the sympathetically induced fluctuations of photoplethysmographic signal in diabetic and non-diabetic subjects

Photoplethysmography (PPG) records the cardiac-induced changes in tissue blood volume by light-transmission measurements. The baseline and amplitude of the PPG signal show very low-frequency (VLF) spontaneous fluctuations, which are mediated by the sympathetic nervous system, and high correlation between right and left extremities of healthy subjects. As sympathetic neuropathy is one of the diabetic complications, the right-left correlation of the PPG fluctuations was examined in diabetic patients. The PPG signal was simultaneously measured in the two index fingers and the two second toes of 35 diabetic patients and 33 non-diabetic subjects. For each PPG pulse, the baseline and amplitude were determined, and the right-left correlation coefficients of the VLF fluctuations in the baseline and amplitude were derived. The VLF fluctuations in the baseline showed high right-left correlation, both for fingers (0.93 +/- 0.05) and toes (0.93 +/- 0.06), for the non-diabetic subjects, and significantly lower correlation (0.78 +/- 0.22 and 0.84 +/- 0.17, respectively) for the diabetic patients. Similar results were obtained for the amplitude VLF fluctuations. The right-left correlation coefficients for diabetic patients decreased with the disease duration for the toe baseline and toe amplitude fluctuations and correlated with heart rate response to deep breathing for the finger baseline and toe amplitude fluctuations. The right-left correlation coefficients of the PPG fluctuations provide a simple and convenient means for assessing the adequacy of the sympathetic nervous system function.

Acroparesthesia and acral arterial occlusions as first manifestations of essential thrombocythemia

Thrombocytosis is either caused by a reactive process (secondary thrombocytosis) or by a clonal bone marrow disorder The latter category includes essential thrombocythemia with bleedings and thrombotic complications as major causes of illness and death in this patients. We describe a 43-year-old man with a 6 months history of acroparesthesia in his toes. Half a year after onset of these symptoms, he noticed a bluish discoloration of digit V of his left foot. On first presentation physical examination revealed a bluish discoloration of all toes and a cold and blue digit V of the left foot. Peripheral pulses were all palpable, normal ankle systolic pressure measurements and normal pulse volume recordings except for digit V of the left foot were found. Laboratory tests revealed thrombocytosis of 800000/microliter. On treatment with acetylsalicylacid, prostanoids intravenously and low molecular weight heparin, the patient became asymptomatic and pulse volume recording of digit V was normalized. After exclusion of cardial or vascular sources of embolism by utrasonography bone marrow aspirate and biopsy supported the diagnosis of essential thrombocythemia.

The aesthetic mini wrap-around technique for thumb reconstruction

In the past 12 years, 16 thumb defects at, or distal to, the interphalangeal joint were reconstructed using a great toe mini wrap-around flap. A flap including the entire nail and most of the distal phalanx of the great toe was used. Fifteen of the grafts survived. The sensory recovery of the reconstructed thumb was good as assessed by 2-point discrimination test with an average of 10 mm (range 5-15), and there were no complaints of cold intolerance. This technique results in good cosmetic appearance, and all patients were pleased with the cosmetic aspect of the thumb and there was no significant morbidity at the great toe donor site. The final decision to reconstruct a distal thumb amputation is influenced by gender, job, and age of the patients. The great toe mini wrap-around flap is an excellent reconstruction technique in selected patients.

[Thermal imaging properties of toes after walking stress test in diabetic patients]

In consecutive 50 diabetic patients hospitalized for medical education, without subjective symptoms of autonomic neuropathy (DM group), performed treadmill walking stress test and thermography, for clarify the feature of the pattern typical of diabetic autonomic neuropathy. Thermal images were collected, before, immediately after, 3, 6, 12 minutes after walking. The mean temperature of toes fell more than 1 degree C than that of baseline level and returned within 0.5 degrees C of baseline level within 6 minutes (N type) in 66% of 30 normal subjects (C group) and 24% of DM group. In 10% of C and 24% of DM, the temperature fell but not returned within 0.5 degrees C of baseline level in 6 minutes (D type). In 17% of C and 38% of DM, the temperature changed within 0.5 degrees C (F type), or rose more than 0.5 degrees C after exercise (U type) in 7% in C and 14% in DM groups. Pts D, F group, have more complications (HbA1c, nephropathy, retinopathy or somatic neuropathy), but not so in C, U type. We concluded D, F types were the typical thermographic features of the toes of pts with diabetic autonomic neuropathy.

Distal site testing of sympathetic skin response (big toe) in diabetic polyneuropathy

The aim of this study was to determine whether the sympathetic skin response (SSR) recorded from the big toe is more sensitive than standard SSR recorded from the sole for the detection of sudomotor fiber dysfunction in diabetic neuropathy. We recorded big toe SSR (SSRBT) and plantar SSR (SSRP) in 17 diabetic patients with non-disabling neuropathy (group A), 13 patients with disabling neuropathy (group B) and 30 age-matched normal controls. With regard to controls, SSRP amplitude was reduced only in group B. In contrast, SSRBT amplitude was reduced in both groups of patients (p<0.0001). In 8 patients in group B, SSRBT was not recordable while the SSRP still persisted. Our results suggest that SS-RBT is a more sensitive test than SSRP in detecting distal sudomotor failure in patients with diabetic neuropathy.

Sensory exam with a quantitative tuning fork: rapid, sensitive and predictive of SNAP amplitude

BACKGROUND

In the standard neurologic examination, outcome measures of sensation testing are typically qualitative and subjective. The authors compared the outcome of vibratory sense evaluation using a quantitative Rydel-Seiffer 64 Hz tuning fork with qualitative vibration testing, and two other features of the neurologic evaluation, deep tendon reflexes and sensory nerve conduction studies.

METHODS

The authors studied 184 subjects, including 126 with Waldenström's macroglobulinemia and 58 controls, over the course of a weekend. Standard neurologic examinations and quantitative vibratory testing were performed. Sensory nerve action potentials (SNAP) were tested as a measure of sensory nerve function. Tests were carried out by different examiners who were blinded to the results of other testing and to clinical information other than the diagnosis of Waldenström's macroglobulinemia.

RESULTS

Quantitative vibration measurements in all body regions correlated with sural SNAP amplitudes. Quantitative vibration outcomes were more strongly related to sural SNAP results than qualitative evaluations of vibration. Quantitative vibration testing also detected a loss of sensation with increased age in all body regions tested.

CONCLUSIONS

Quantitative vibratory evaluation with Rydel-Seiffer tuning fork is rapid, has high inter- and intrarater reliability, and provides measures for evaluating changes in sensory function over time. Examinations with the quantitative tuning fork are also more sensitive and specific than qualitative vibration testing for detecting changes in sensory nerve function. Use of the quantitative tuning fork takes no more time, provides more objective information, and should replace the qualitative vibratory testing method that is now commonly used in the standard neurologic examination.

The multiple monoblock toe-to-hand transfer in digital reconstruction. a report of ten cases

Ten hands with multiple traumatic finger amputations or congenital agenesis underwent reconstruction by monoblock transfer of multiple toes. Eight patients underwent monoblock transfer of the great and second toes, one patient received the great toe and the metatarsophalangeal joint from the second toe with the same vascular pedicle, and another patient the great, second and third toes as a block. Only part of the great toe was ever taken, while the second toe was totally or partially taken. The surgical technique and the outcome are detailed in this work, with a mean postoperative follow-up of 6 years.

[A 68-year-old man of dural arteriovenous fistula at the cranio-cervical junction with dysesthesia ascending from his both toes]

We reported a 68-year-old man of dural arteriovenous fistula at the cranio-cervical junction with dysesthesia ascending from his both toes. He recognized dysesthesia at his both toes 10 months previously. Thereafter dysesthesia ascended to his girdle which was stronger as far as his girdle and gait disturbance developed. Somatosensory evoked potential (SEP) revealed delayed central conduction time. Cervical MRI showed a swelling of the spinal cord and intramedullary hyperintense lesion from the C2 to C7 level on the T2-weighted image. Moreover flow void behind the mudulla oblongata on the T2-weighted MRI was outstanding. Angiogram through right ascending pharyngeal artery revealed enlarged and tortuous anterior and posterior spinal veins at the early arterial phase. We diagnosed as dural arteriovenous fistula (AVF) and conducted intraarterial embolization. After treatment, the swelling and hyperintense lesion of the cervical spinal cord improved on MRI, and flow void behind medulla oblongata was extinguished. Gait disturbance also improved. We think that the valves of veins in the spinal cord are responsible for the tendency of higher venous pressure in outer circumference, which results in the symptom dominating in the lower extremities. We recommend that dural AVF at the cranio-cervical junction should be considered as a differential diagnosis in case with the similar clinical course to our case.

Receptive field scatter, topography and map variability in different layers of the hindpaw representation of rat somatosensory cortex

We recorded neurons extracellularly in layers II/III, IV, and V of the hindpaw representation of primary somatosensory cortex in anesthetized rats and studied laminar features of receptive fields (RFs) and representational maps. On average, RFs were smallest in layer IV and largest in layer V; however, for individual penetrations we found substantial deviations from this rule. Within the hindpaw representation, a distinct rostrocaudal gradient of RF size was present in all layers. While layer V RFs were generally largest independent of this gradient, layer IV RFs recorded caudally representing the proximal portions of the paw were larger than layer II/III RFs recorded rostrally representing the digits. The individual scatter of the locations of RFs across laminar groups was in the range of several millimeters, corresponding to about 25% of the average RF diameter. The cutaneous representations of the hindpaw in extragranular layers were confined to the areal extent defined by responsive sites in layer IV. Comparison between RFs determined quantitatively and by handplotting showed a reliable correspondence. Repeated measurements of RFs revealed spontaneous fluctuations of RF size of no more than 5% of the initial condition over an observation period of several hours. The topography and variability of cortical maps of the hindpaw representation were studied with a quantitative interpolation method taking into account the geometric centers of RFs and the corresponding cortical recording sites. On average, the overall topography in terms of preservation of neighborhood relations was present in all layers, although some individual maps showed severe distortions of topography. Factors contributing to map variability were overall position of the representation on the cortical surface, internal topography and spatial extent. Interindividual variability of map layout was always highest in the digit representations. Local topographic orderliness was lowest in layer V, but comparable in layers II/III and IV. Within layer IV, the lowest orderliness was observed in the digit representations. Our data emphasize a substantial variability of RF size, overlap and position across layers and within layers. At the level of representational maps, we found a similar degree of variability that often co-varied across layers, with little evidence for significant layer specificity. Laminar differences are likely to arise from the specific input-output pattern, layer-specific cell types and the connectivity between different layers. Our findings emphasizing similarities in the variability across layers support the notion of tightly coupled columnar interactions between different layers.

An assessment of vascular pain using the flexor reflex in anesthetized rats

This study assessed the flexor reflex induced by intraarterial algogenic drugs in anesthetized rats. The experiments were performed on male Sprague Dawley rats weighing 290-350 g. The animals were anesthetized with urethane (1.3 g/kg i.p.) and an arterial cannula was inserted to the level of the bifurcation of the femoral artery. The magnitude of the flexor reflex was examined by recording the electromyograph from the posterior biceps femoris/semitendinous muscles. Results showed that the flexor reflex evoked by intra-arterial injection of capsaicin (0.05-0.5 microg) was dose-dependent. A similar reflex resulted from pinching the toe of the hindlimb. These responses were inhibited by morphine (5 mg/kg s.c.) and restored with naloxone (1.5 mg/kg s.c.). Intraarterial preinjection of procaine (2%, 200 microl) and capsazepine (20 microg), which is a selective vanilloid receptor antagonist, inhibited the capsaicin-evoked response, but not that of pinching. These results indicate that the flexor reflex is a useful tool for assessing vascular pain in anesthetized animals.

Interventions for the treatment of Morton's neuroma

BACKGROUND

Morton's neuroma is a common, paroxysmal neuralgia affecting the web spaces of the toes, typically the third. The pain is often so debilitating that patients become anxious about walking or even putting their foot to the ground. Insoles, corticosteroid injections, excision of the nerve, transposition of the nerve and neurolysis of the nerve are commonly used treatments. Their effectiveness is poorly understood.

OBJECTIVES

To examine the evidence from randomised controlled trials concerning the effectiveness of interventions in adults with Morton's neuroma.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group trials register (searched January 2003), MEDLINE (January 1966 to January Week 2 2003), EMBASE (January 1980 to February Week 2 2003), and CINAHL (January 1982 to February Week 1 2003).

SELECTION CRITERIA

Randomised or quasi-randomised (methods of allocating participants to an intervention which were not strictly random e.g. date of birth, hospital record, number alternation) controlled trials of interventions for Morton's neuroma were selected. Studies where participants were not randomised into intervention groups were excluded.

DATA COLLECTION AND ANALYSIS

Two reviewers selected trials for inclusion in the review, assessed their methodological quality and extracted data independently.

MAIN RESULTS

Three trials involving 121 people were included. There is, at most, a very limited indication that transposition of the transected plantar digital nerve may yield better results than standard resection of the nerve in the long term. There is no evidence to support the use of supinatory insoles. There are, at best, very limited indications to suggest that dorsal incisions for resection of the plantar digital nerve may result in less symptomatic post-operative scars when compared to plantar excision of the nerve.

REVIEWERS' CONCLUSIONS

There is insufficient evidence with which to assess the effectiveness of surgical and non-surgical interventions for Morton's neuroma. Well designed trials are needed to begin to establish an evidence base for the treatment of Morton's neuroma pain.

Sensory dysfunction in the great toe in hallux valgus

Injury to the dorsomedial cutaneous nerve in the foot may occur after operations for hallux valgus. Pressure neuropathy before operation is also described but remains largely unexplored. We have investigated the incidence of sensory deficit in the great toe before operating for hallux valgus and examined to what extent any deficit was related to the degree of angulation of the joint. Forty-three patients with a total of 61 great toes with hallux valgus presenting for consideration of surgical correction had their sensation tested in pre-designated zones using a five-filament set of Semmes-Weinstein monofilaments. These allowed good inter-observer reliability with an intra-class correlation coefficient of 0.84. Sensory symptoms were noted by only 21% of the patients, a measurable reduction in sensation by one monofilament grade or more was found in an additional 44%. No relationship was found between the degree of sensory loss and the degree of angulation. Patients with symptomatic hallux valgus may have sensory loss in the toe without being aware of it. Normal subjective sensation does not reliably predict normal sensory function. Given the potentially high rates of nerve damage following operations for hallux valgus, we recommend objective sensory testing as part of routine assessment before surgery.

[Branched form of the encapsulated dermal receptors in rats]

Using electron microscope the receptors found in the zone of highest receptor sensitivity in the skin fold at the base of IV finger of rat hind limb were studied. These receptors are represented by complex incapsulated corpuscles consisting of a group of small endings similar to Pacinian corpuscles, which are densely packed and surrounded by a common connective tissue capsule. Each single primary receptor is provided with an unmyelinated receptor terminal, analogue of internal bulb, and a multilayered external bulb. Primary receptor differs from Vater-Pacinian corpuscle by a significantly smaller size, form of sensitive terminal in cross-section, small number of layers forming internal and external bulbs. Complex corpuscle is the derivative of n. tibialis myelinated sensory fiber. The later is divided after the loss of myelin forming a platform of division with several (up to 5) short sprouts and separate incapsulated receptors at their ends. The complex corpuscles described apparently are dermal mechanoreceptors.