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[Transcallosal modulation of a focus of maximal activity in the motor cortex].

In acute experiments on cats, when recording EPs from 170 symmetrical points of the motor cortex, callosal influence on the maximal activity focus (MAF) was studied in conditions of stimulation of the sciatic nerves with different stimuli. After callosal transection, weak stimuli enlarged the MAF, strong one-narrowed it. The transcallosal modulation in intact brain is supposed to aid to delineate the MAF in the motor cortex and to exaggerate the differences between MAFs occurring at stimulation with different stimuli.

Animals↗

Forelimb muscle contraction induced by cerebral cortical stimulation after callosotomy: a myographic study in the mouse.

The effect of callosotomy upon motor control by the cerebral cortex on the forelimb was examined in the mouse. On the 10th day after callosotomy in the rostral or caudal part of the corpus callosum, the forelimb area of the cerebral motor cortex was stimulated intracortically with a microelectrode and muscle contraction of the forelimb was recorded by electromyography. Muscle contraction was observed in the contralateral forelimb in the mice of which callosal fibers were cut in the caudal part of the corpus callosum including the splenium corporis callosi as well as in the normal mice. On the other hand, muscle contraction was observed in the ipsilateral forelimb in the mice of which callosal fibers were incised in the rostral part of the corpus callosum including the genu, rostrum and trunk. The latency of the muscle contraction was about 0.5 msec in the both groups of the callosotomized mice, as well as in the normal mice.

Animals↗

[Formation of systems of unilateral conditioned reflexes following section of the rostral portion of the corpus callosum].

Unilateral conditioned reflexes and two-link reflex systems with regular rhythmic alternation of positive and inhibitory reflexes were elaborated by Abuladze method in four dogs with a preliminarily dissected rostral part of the callosal body. Whereas the rate of formation of simple unilateral positive reflexes did not differ from that of reflex formation in intact animals, the formation of two-link unilateral systems proved to be disturbed. In spite of considerable stabilization of positive and inhibitory reflexes, ultraparadoxical relations were revealed when the same stimuli were applied in the system which testified to the disturbance of the after-effect dynamics. It has been assumed that rostral parts of the callosal body take part in the fixation of traces as the first component of the memory mechanism.

Animals↗

[Arterial and venous vascularization of the corpus callosum].

Blood supply of the corpus callosum is assured by two arterial systems, the carotid system mainly and the vertebrobasilar system accessorily. The carotid system intervenes via the pericallosal artery, portion of the anterior cerebral artery distal to the anterior communicating artery. This pericallosal artery can be bihemispheric in 4 to 12% of the cases or azygos in 0.26% of cases. In 20 to 80% of cases, the median callosal artery arises from the communicating artery. The vertebrobasilar system intervenes in splenium vascularization by its terminal branches. These two carotid and vertebrobasilar systems give rise to perforating arteries that assure intrinsic vascularization of the corpus callosum creating a system of regular vascular stitches around the fibers of the corpus callosum. The venous drainage of the corpus callosum is essentially via callosal veins and callosocingulate veins towards the deep venous system of the brain.

Animals↗

Neuroimaging manifestations and classification of congenital muscular dystrophies.

BACKGROUND AND PURPOSE: Recent work has shown that up to 50% of patients with congenital muscular dystrophies (CMDs) have abnormalities of the brain that can be detected by brain MR imaging. We attempted to determine whether brain MR imaging is useful for the diagnosis and classification of patients with CMDs. METHODS: The brain MR studies of 12 patients with biopsy-proved CMDs were reviewed retrospectively. Using information available in the literature regarding associated brain anomalies as a guide, an attempt was made to classify the patients in terms of "pure" CMD, CMD with occipital agyria, Fukuyama CMD, muscle-eye-brain disease, or Walker-Warburg syndrome. RESULTS: All the patients were easily classified into one of four groups: pure CMD (four patients), Fukuyama CMD (four patients), muscle-eye-brain disease (two patients), or Walker-Warburg syndrome (two patients). Patients with pure CMD had diffuse central cerebral hypomyelination with mild pontine and cerebellar hypoplasia. Patients with Fukuyama CMD had diffuse central cerebral hypomyelination, cerebellar polymicrogyria (with or without cysts), frontal polymicrogyria, a variable degree of hypoplasia of the pons and cerebellar vermis, and a variable occipital cobblestone cortex. Patients with muscle-eye-brain disease had cerebellar polymicrogyria (with or without cysts), absence of the septum pellucidum, diffuse cerebral cortical dysplasia, pontine and cerebellar vermian hypoplasia, patchy hypomyelination, and variable callosal hypogenesis and hydrocephalus. Patients with Walker-Warburg syndrome had diffuse cerebral cobblestone cortex, absence of cerebral and cerebellar myelin, cerebellar polymicrogyria (with or without cysts), pontine and cerebellar vermal hypoplasia, hydrocephalus, and variable callosal hypogenesis. CONCLUSION: MR imaging shows distinctive brain anomalies that allows patients with CMD to be classified into four distinct groups that are consistent with known disorders.

Biopsy↗

[Effect of high frequency cortical microstimulation on the interhemisphere synchronization in the rat motor cortex].

Long-term posttetanic changes of callosal neurons' synchronisation was studied in the rat motor cortex. Following tetanisation, the synchronisation of previously active cells decreased whereas the cells that became active were mostly synchronised. Ultra "narrow" peaks appeared in callosal interactions and correlated with "intermediate" (30-80 ms) those.

Action Potentials↗

[Characteristics and mechanisms of the interhemisphere synchronization in the rat motor cortex].

Synchronised activity of the callosal cells was studied in the rat motor cortex. Cross-correlation analysis revealed narrow symmetrical peaks (less than 20 ms) and intermediate ones (30-80 ms). Common neuron(s) located in one hemisphere reciprocally connected callosal cells can play the role of a "common input" that synchronises discharges of the cells in both hemispheres. The narrow and intermediate peaks seem to be mediated by mono- and polysynaptic connections, resp.

Action Potentials↗

Interhemispheric connections of somatosensory cortex in the flying fox.

The interhemispheric connections of somatosensory cortex in the gray-headed flying fox (Pteropus poliocephalus) were examined. Injections of anatomical tracers were placed into five electrophysiologically identified somatosensory areas: the primary somatosensory area (SI or area 3b), the anterior parietal areas 3a and 1/2, and the lateral somatosensory areas SII (the secondary somatosensory area) and PV (pairetal ventral area). In two animals, the hemisphere opposite to that containing the injection sites was explored electrophysiologically to allow the details of the topography of interconnections to be assessed. Examination of the areal distribution of labeled cell bodies and/or axon terminals in cortex sectioned tangential to the pial surface revealed several consistent findings. First, the density of connections varied as a function of the body part representation injected. For example, the area 3b representation of the trunk and structures of the face are more densely interconnected than the representation of distal body parts (e.g., digit 1, D1). Second, callosal connections appear to be both matched and mismatched to the body part representations injected in the opposite hemisphere. For example, an injection of retrograde tracer into the trunk representation of area 3b revealed connections from the trunk representation in the opposite hemisphere, as well as from shoulder and forelimb/wing representations. Third, the same body part is differentially connected in different fields via the corpus callosum. For example, the D1 representation in area 3b in one hemisphere had no connections with the area 3b D1 representation in the opposite hemisphere, whereas the D1 representation in area 1/2 had relatively dense reciprocal connections with area 1/2 in the opposite hemisphere. Finally, there are callosal projections to fields other than the homotopic, contralateral field. For example, the D1 representation in area 1/2 projects to contralateral area 1/2, and also to area 3b and SII.

Animals↗

[Bilateral mechanisms of interference resistance in the parastriate cortex].

The influence of photic interference is manifested in animals (in cats) with an intact callosal body mainly in EP depression. The extent of EP depression depends directly on the strength of the interference and is inversely related to that of the determined stimulus. In some cases yet another effect, facilitation of EP may be manifested during the action of a weak interference. These facts are considered to result from postrevely. Section of the callosal body is followed by a weakening of the depressing influence of photic interference on EPs elicited by a certain stimulus, as well as by an enhancement of the facilitating influence on EPs of weak photic interferences. A stronger influence of a binocular photic interference, as compared with a monocular one, has been established in intact and callosotomized animals. A conclusion has been drawn that the interference resistance of a split brain is stronger than that of an intact one. A comparison of the interference resistance in the primary and secondary cortical visual projection zones has shown that after callosotomy interference resistance in the striate cortex increases to a greater extent than in the parastriate area.

Animals↗

Clinical application of retrograde island flap pedicled with lateral plantar artery.

The purpose of the study is to identify a repair procedure for the ulcers or defect of the anterior lateral plantar region. The defects of anterior lateral plantar region after resection of the obstinate ulcer, painful corns and callosity were repaired by the retrograde island flap pedicled with lateral plantar artery. One to 10 years following up revealed that all the 10 flaps in 9 patients survived after operation. Patients walked freely without pain and claudication. The flap did not show any sign of damages of the flap even if the patients walked for a long time. It is concluded that the retrograde island flap pedicled with lateral plantar artery is the best choice in repairing the defects of anterior lateral plantar region.

Adolescent↗

The inadequate effect of automobile seating on foot posture and callus development.

Driver posture is an important factor to be considered in the ergonomics design process of automobiles. Most decisions during automobile design and manufacture are informed by studying the intricate biomechanical components of human musculoskeletal systems to ensure maximum comfort, safety and well-being during driving. A case study is presented that confirms inappropriate foot position as a causative factor for the development of abnormal lateral/plantar heel callosities when driving a 4 x 4-style vehicle. The driver's foot position was influenced by the seat geometry of the vehicle. Cessation of driving the 4 x 4-style vehicle and driving of an alternative automobile while on holiday for a period of 4 weeks resolved the condition. On return to the 4 x 4-style vehicle, however, the abnormal callus patterns redeveloped while using the same footwear and no change in any other parameters. It is therefore suggested that seat and consequent foot position is an important ergonomic factor that should be addressed in the future design of automobile seating.

Adult↗

Arthroplasty for rheumatoid forefoot deformities by a shortening oblique osteotomy.

Seventy-five feet in 47 patients (46 women, 1 man) who had rheumatoid arthritis were observed for an average of 6 years (range, 4-11 years) after an operation on the forefoot that included a shortening oblique osteotomy of the metatarsal neck of the lateral toes. In addition, patients underwent either flexible hinge toe implant arthroplasty or Mitchell's osteotomy in the first metatarsophalangeal joint. Forty-two feet (56%) looked normal with no valgus or dorsal displacement of the toes. Recurrence of callosities occurred in 9 feet (12%) with moderate pain in 3 feet. Thirty-nine (83%) patients were satisfied with the outcome after surgery. Resection arthroplasty often is recommended for management of forefoot deformities. However, as shown in this series, the improvement in deformities, function, and cosmesis of metatarsophalangeal joint preservation may be better with an osteotomy of the metatarsal neck than with a resection arthroplasty. Because of the development of combined drug therapy, the benefits of synovectomy, osteotomy, and shortening in length should be reconsidered. The authors' studies suggest that the shortening oblique osteotomy should be considered 1 of the surgical reconstruction options for patients with rheumatoid arthritis who have forefoot deformities.

Adult↗

Knuckle pads in live-chicken hangers.

A study of live-chicken hangers in a poultry processing plant demonstrated a high prevalence of callosities over the knuckles (knuckle pads) of both hands. Knuckle pads were observed in 56% (23/41) of live-chicken hangers, but in no (0/41) workers from other departments (p less than 0.001). The probable cause was the repeated striking and sliding of the knuckles against metal shackles in which live birds were being placed. Additional medical and ergonomic evaluation would be worthwhile to confirm the probable cause, to determine whether associated tissue disorders are present in the digits of chicken hangers who develop knuckle pads, and to suggest preventive measures.

Adult↗

Operative repair of fourth and fifth toe corns.

METHODS: We report a retrospective review of 57 consecutive patients (72 feet) over a period of 20 years who had been treated operatively for either a lateral fifth toe corn or an interdigital corn of the fourth interdigital space more than two years previously. Of these, 51 patients (62 feet) returned for a follow-up evaluation at a minimum of two years (average of over seven years) which included a review of the interval history since the surgery, a physical examination, a radiographic evaluation, and assessment of the patient's satisfaction with the alignment and results of surgery. Treatment of 31 lateral fifth toe corns involved either a lateral condylectomy and flexor tenotomy or a complete condylectomy. Treatment of 31 interdigital corns comprised either a single condylectomy, double condylectomy of adjacent corns, or a complete condylectomy (hammertoe repair) of a symptomatic corn. Treatment in each case was dependent upon the severity of the deformity. RESULTS: There was found to be no significant difference in comparison of the two major groups (interdigital corns and lateral fifth toe corns) with the measurement of the relative length of the fourth and fifth metatarsals, toe malalignment, angulation of the fourth and fifth toes (MTP-4, MTP-5 angles), and the phalangeal-5 angle. Pain was relieved in 58 of 62 feet (93%) and subjective acceptable alignment was achieved in 54 of 62 feet (87%). At final follow-up 53 feet were rated by patients as excellent, seven as good, one as fair, and one as poor. Complications included numbness of the involved digit (six feet). There were two superficial infections. There were two cases of joint instability due to excessive bone resection. Joint stiffness was commonly observed (34/62 feet, 55%), but was not associated with diminished satisfaction at final follow-up. Mild asymptomatic recurrence of a callosity was noted in 10 feet and moderate or severe recurrence was noted in two feet. Dissatisfaction was associated with moderate or severe recurrence. CONCLUSION: In this retrospective study at an average of more than seven years, we achieved a high level of patient satisfaction treating both lateral fifth toe corns and interdigital corns with a partial and/or complete condylectomy, the choice depending upon the magnitude of the deformity and the callus, and the fixed nature of the lesser toe deformity.

Adult↗

Intrinsic toe flexion deformity following correction of spastic equinovarus deformity in adults.

In the treatment of spastic equinovarus foot deformities in adults with neurologic impairment, various surgical procedures are used including the split anterior tibialis tendon transfer and tendo achilles lengthening. Release of the flexor hallucis longus and flexor digitorum longus tendons in the midfoot is routinely included with these procedures to correct or prevent toe curling. In follow-up, residual toe curling has been observed in some patients despite release of the long toe flexor tendons. This study was undertaken to investigate this problem and its consequences, treatment, and treatment success. Forty-one feet in 34 consecutive patients were examined for residual toe curling an average of 2.5 years postoperatively. Thirty-two feet (78%) were noted to have significant flexion deformities of the lesser toes. The residual toe curling caused pain in 72% of the feet and was associated with callosities on the dorsum of the toes in 59%. The incidence of residual toe curling secondary to spasticity of the flexor digitorum brevis and intrinsic muscles of the foot was similar in the patients who had sustained traumatic brain injury and in those who had suffered a cerebrovascular accident. Twelve of these feet (37%) underwent surgical release of the flexor digitorum brevis and intrinsic tendons to correct the toe curling. There were no complications of surgery and no recurrences of deformity following the surgery. A second surgical procedure to release the flexor digitorum brevis and intrinsic tendons to correct the toe curling was more commonly performed in the younger more active brain-injured patients than in the older stroke patients (44% versus 20%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Congenital dysplasia of the heel fat pad: a case report of a previously undescribed entity.

We describe a 13-year-old girl who was born with a congenital anomaly of her left heel fat pad. We call this anomaly congenital dysplasia of the heel pad, due to under development of all elements of the heel fat pad. In the case presented the vertical fibrous septa were missing and the amount of fat and its distribution were abnormal. As a result, the abnormal biomechanical shock absorber mechanism caused a painful callosity formation. A surgical procedure aiming to produce adhesions between the fat pad and the calcaneous in order to decrease the shear of the heel pad was only partially successful. Different types of orthotic devices did not resolve the clinical problem of the painful heel. Such a congenital anomaly has never been described in the English literature, and we coined the term congenital dysplasia for the previously undescribed entity.

Adipose Tissue↗

Oblique metatarsal osteotomy for intractable plantar keratosis: 10-year follow-up.

Twenty patients (14 women and 6 men) (23 feet) had a single oblique osteotomy operation of the 2nd, 3rd, or 4th metatarsal without fixation during an 8-year period. The mean age was 46 years (range, 21-64 years). Each patient had a painful intractable plantar keratosis preoperatively. The average follow-up was 10 years (range, 3-14 years). Postoperatively, reoperation was performed in four feet because of painful callosities. For 13 of the 19 feet that did not have reoperation, patients were limited in footwear or required a shoe insert. Overall results were good for 10 feet, fair for 7 feet, and poor for 6 feet. The only complication was a deep infection that occurred in one foot (good result). Nonunion occurred in one foot and delayed union in one. The average decrease in metatarsal length after osteotomy was 6+/-6 mm. The single oblique lesser metatarsal osteotomy may be successful, but one half of the patients continued to have some degree of pain and most patients had limitations in footwear. Overall results were disappointing, and patients who are offered this procedure should be advised of its limitations.

Adult↗

Lengthening of short great toes by callus distraction.

We lengthened seven first metatarsals in four patients with short great toes by callus distraction using an external fixator. Good clinical and cosmetic results were obtained. Bone lengthening is effective in patients with short great toes not only for cosmesis, but also to relieve pain and callosities on the plantar aspect of the second and third metatarsal heads. Excessive lengthening of the first metatarsal resulted in limitation of the range of movement of the metatarsophalangeal joint of the great toe. To prevent this the amount of lengthening should not exceed 40% of the preoperative length of the metatarsal.

Adult↗