Peripheral and central mechanisms of hindfoot equinus in childhood hemiplegia

Dystonia in Childhood: How Insights from Paediatric Research Enrich the Network Theory of Dystonia

Dystonia is now widely accepted as a network disorder, with multiple brain regions and their interconnections playing a potential role in the pathophysiology. This model reconciles what could previously have been viewed as conflicting findings regarding the neuroanatomical and neurophysiological characteristics of the disorder, but there are still significant gaps in scientific understanding of the underlying pathophysiology. One of the greatest unmet challenges is to understand the network model of dystonia in the context of the developing brain. This article outlines how research in childhood dystonia supports and contributes to the network theory and highlights aspects where data from paediatric studies has revealed novel and unique physiological insights, with important implications for understanding dystonia across the lifespan.

Multi-segment foot model reveals distal joint kinematic differences between habitual heel-toe walking and non-habitual toe walking

Toe walking is observed in pathological populations including cerebral palsy, stroke, and autism spectrum disorder. To understand pathological toe walking, previous studies have analyzed non-habitual toe walking. These studies found sagittal plane deviations between heel-toe and toe walking at the hip, knee, and ankle. Further investigation is merited as toe walking may involve altered biomechanics at more distal joints, such as the midtarsal joint. The purpose of this study was to examine biomechanical differences between rearfoot strike walking (RFSW) and non-rearfoot strike walking (NRFSW) in the midfoot and ankle. We hypothesized that during NRFSW, midtarsal kinematics would diverge from those during RFSW in all three cardinal planes and ankle kinematics would display increased supination. Twenty-four healthy females walked overground with both walking patterns. Motion capture, electromyography (EMG), and force plate data were collected. A validated multi-segment foot model was used with mean difference waveform analyses to compare walking conditions during stance. Significantly different kinematics were found in all three planes for the midtarsal and ankle joint during NRFSW. The NRFSW midtarsal joint exhibited increased plantarflexion, eversion, and adduction with the largest differences occurring at initial contact and in the sagittal plane. The NRFSW ankle exhibited increased supination at initial contact and during early stance. These findings indicate that toe walking alters both distal and proximal foot joint kinematics in multiple planes. This may further the understanding of altered biomechanics during toe walking while providing a basis for future analyses of pathological gait.

Cerebral palsy

Cerebral palsy is the most common cause of childhood-onset, lifelong physical disability in most countries, affecting about 1 in 500 neonates with an estimated prevalence of 17 million people worldwide. Cerebral palsy is not a disease entity in the traditional sense but a clinical description of children who share features of a non-progressive brain injury or lesion acquired during the antenatal, perinatal or early postnatal period. The clinical manifestations of cerebral palsy vary greatly in the type of movement disorder, the degree of functional ability and limitation and the affected parts of the body. There is currently no cure, but progress is being made in both the prevention and the amelioration of the brain injury. For example, administration of magnesium sulfate during premature labour and cooling of high-risk infants can reduce the rate and severity of cerebral palsy. Although the disorder affects individuals throughout their lifetime, most cerebral palsy research efforts and management strategies currently focus on the needs of children. Clinical management of children with cerebral palsy is directed towards maximizing function and participation in activities and minimizing the effects of the factors that can make the condition worse, such as epilepsy, feeding challenges, hip dislocation and scoliosis. These management strategies include enhancing neurological function during early development; managing medical co-morbidities, weakness and hypertonia; using rehabilitation technologies to enhance motor function; and preventing secondary musculoskeletal problems. Meeting the needs of people with cerebral palsy in resource-poor settings is particularly challenging.

Distal Vibration Perception Threshold in Children Who Toe Walk

PURPOSE

To compare distal vibratory perception threshold and sensation in children who toe walked (TW) and controls.

METHODS

Vibration perception threshold was measured at the metacarpal and metatarsal phalangeal (MCP and MTP) joints in 11 TW and 15 age-matched controls. Mean vibratory threshold (MVT) was calculated for each site; a Pearson correlation coefficient was determined for MVT at MCP and MTP joints. Groups were compared using a Mann-Whitney U test. Parent/caregiver responses on the Short Sensory Profile (SSP) were compared using a χ test.

RESULTS

MVTs at the MCP and MTP joints were highly correlated in both groups. MVT was higher in TW compared with controls at each site. Children who TW were more likely to have a total SSP score in the "probable difference" or "definite difference" categories compared with the "no difference" category.

CONCLUSION

Sensation should not be overlooked in the evaluation and clinical management of toe walking.

Gait post-stroke: Pathophysiology and rehabilitation strategies

We reviewed neural control and biomechanical description of gait in both non-disabled and post-stroke subjects. In addition, we reviewed most of the gait rehabilitation strategies currently in use or in development and observed their principles in relation to recent pathophysiology of post-stroke gait. In both non-disabled and post-stroke subjects, motor control is organized on a task-oriented basis using a common set of a few muscle modules to simultaneously achieve body support, balance control, and forward progression during gait. Hemiparesis following stroke is due to disruption of descending neural pathways, usually with no direct lesion of the brainstem and cerebellar structures involved in motor automatic processes. Post-stroke, improvements of motor activities including standing and locomotion are variable but are typically characterized by a common postural behaviour which involves the unaffected side more for body support and balance control, likely in response to initial muscle weakness of the affected side. Various rehabilitation strategies are regularly used or in development, targeting muscle activity, postural and gait tasks, using more or less high-technology equipment. Reduced walking speed often improves with time and with various rehabilitation strategies, but asymmetric postural behaviour during standing and walking is often reinforced, maintained, or only transitorily decreased. This asymmetric compensatory postural behaviour appears to be robust, driven by support and balance tasks maintaining the predominant use of the unaffected side over the initially impaired affected side. Based on these elements, stroke rehabilitation including affected muscle strengthening and often stretching would first need to correct the postural asymmetric pattern by exploiting postural automatic processes in various particular motor tasks secondarily beneficial to gait.

Cerebral palsy of the elbow and forearm

Management of elbow and forearm involvement in cerebral palsy has evolved over the last 3 decades with a better understanding of its neuropathophysiology, improved outcome measures, and evolving therapy protocols. Current nonoperative and surgical treatment methods are discussed. The use of standard function measuring instruments and encouragement of the participation in research will hopefully result in more accurate outcome information and, thereby, refine our techniques and rehabilitation methods.

Functional priorities in daily life for children and young people with dystonic movement disorders and their families

PURPOSE

This study aims to describe the most prevalent functional concerns of a group of young people with dystonia and their primary carers, and to explore the relationship between concerns, aetiology, severity of motor disability and manual ability.

METHOD

The Canadian Occupational Performance Measure (COPM) was completed with 57 children with dystonic movement disorders (65% males/35% females, mean 11.2 years (3.5-18.1)): 25% had primary dystonia, 75% secondary dystonia. Gross motor and manual function were classified using the Gross Motor Function Classification System (GMFCS) and the Manual Ability Classification System (MACS). COPM concerns were analysed with respect to aetiology and severity of motor disability.

RESULTS

Almost three quarters of the respondents were GMFCS/MACS IV-V. All respondents had at least one concern around self-care. Other concerns included access to assistive technology, pain, dressing activities, use of tools and social participation. The nature and presence of concerns did not statistically differ according to the severity of gross motor or manual function impairment, though qualitative differences were noted. No statistical difference was found in relation to aetiology.

INTERPRETATION

Children and young people with dystonia have common functional concerns and priorities independent of the cause of dystonia, gross motor severity or manual function ability.

Tibialis anterior tendon shortening in combination with Achilles tendon lengthening in spastic equinus in cerebral palsy

Equinus is the commonest deformity in cerebral palsy (CP). Many different surgical procedures have been described for the treatment of spastic equinus. In long standing equinus deformities the tibialis anterior muscle becomes elongated which is one reason for muscle weakness. Surgical tendon shortening of the tibialis anterior tendon was therefore introduced to rebalance muscle strength. All patients with CP who had a tibialis anterior tendon shortening (TATS) in combination with a tendo Achilles lengthening (TAL) were included in this study. A total of 29 patients had 30 surgical interventions (21 hemiplegic patients: 14 boys/7 girls, age 9-22 years; mean 15.2 years; 5 diplegics and 3 quadriplegics; 5 boys/3 girls, age 7-37.5 years; mean 14.8 years). Fifteen patients had additional surgery (soft tissue or bony procedures). The TATS was performed at the distal insertion with transosseous tendon fixation in the medial cuneiform bone at the original place. Movement Analysis Profile (MAP) for ankle dorsi-/plantarflexion, Gait Profile Score (GPS), Gait Deviation Index (GDI), and Gillette Gait Index (GGI) improved significantly for all patients compared pre- to postoperatively. In 93% of the patients active dorsiflexion of the ankle was possible postoperatively. We conclude that TATS in combination with TAL in spastic equinus in CP is a safe procedure and improves but not completely corrects foot positioning during gait. For the treatment of spastic equinus in CP we recommend shortening of the elongated antagonist (TATS) in combination with lengthening of the short agonist (TAL) for achieving optimal postoperative function.

Spastic movement disorder: impaired reflex function and altered muscle mechanics

In clinical practice, signs of exaggerated tendon tap reflexes associated with muscle hypertonia are generally thought to be responsible for spastic movement disorders. Most antispastic treatments are, therefore, directed at the reduction of reflex activity. In recent years, however, researchers have noticed a discrepancy between spasticity as measured in the clinic and functional spastic movement disorders, which is primarily due to the different roles of reflexes in passive and active states, respectively. We now know that central motor lesions are associated with loss of supraspinal drive and defective use of afferent input with impaired behaviour of short-latency and long-latency reflexes. These changes lead to paresis and maladaptation of the movement pattern. Secondary changes in mechanical muscle fibre, collagen tissue, and tendon properties (eg, loss of sarcomeres, subclinical contractures) result in spastic muscle tone, which in part compensates for paresis and allows functional movements on a simpler level of organisation. Antispastic drugs can accentuate paresis and therefore should be applied with caution in mobile patients.

Secondary gait compensations in individuals without neuromuscular involvement following a unilateral imposed equinus constraint

Ankle equinus is the most commonly identified impairment of individuals with spastic hemiplegia (SH). However, it is not clear how equinus at the ankle may contribute to gait deviations at other joints. The purpose of this study was to determine what compensatory gait deviations may occur as a result of an imposed, unilateral equinus constraint. Gait data were collected on 12 adult subjects with and without one ankle constrained in equinus using a unique taping method. Knee extension at initial contact, knee extension in mid stance, and hip extension at terminal stance were all found to be significantly reduced on the ipsilateral side as a result of the ankle constraint. On the unconstrained or contralateral side, subjects tended to adopt a foot-flat or toe-first initial contact pattern. This study suggests that stance phase limitations in both hip and knee extension in the gait of persons with hemiplegia are not necessarily caused by limited length of the involved side hamstrings and/or hip flexors, but rather that they can occur as the result of an ankle plantarflexor contracture alone. Deviations in the contralateral foot contact pattern can also occur secondary to unilateral equinus and should not be assumed to represent bilateral involvement.

Keep on your toes: gait initiation from toe-standing

Gait initiation from toe-standing is common in patients with upper motor neurone (UMN) pathology as well as in able-bodied subjects during certain dance and athletic situations. It is unclear whether balance problems in patients who toe-walk are due to the underlying pathology, or due to initiating gait from toe-standing. The aim of this study was to compare the biomechanics of gait initiation from toe-standing to that from heel-toe standing in healthy able-bodied subjects. Data were collected for three seconds prior to, and three seconds after, a visual signal to initiate gait. Ground reaction force and centre of pressure (COP) data were collected with an AMTI force platform, and electromyographic and kinematic data were collected from each limb with a Vicon motion analysis system. When initiating gait from toe-standing, there was a smaller backward displacement of the COP compared to heel-toe standing. In addition, greater forward momentum was generated, and there was an increase in gastrocnemius, rectus femoris and biceps femoris muscle activity. There were no differences in COP displacement or momentum generated in the mediolateral direction for the two conditions. Thus, initiating gait from toe-standing allows one to generate greater amounts of forward momentum but not at the expense of generating excessive stance-side momentum. This may be an advantageous method of initiating movement for dancers and athletes in certain situations. This work also suggests that balance problems in patients with UMN pathology are likely due to the underlying pathology and are not due to initiating gait from toe-standing.

Spasticity: orthopedic perspective

The orthopedic management of spasticity is based on the effects of this neurologic condition on the bones and tissues of the growing child. The goal of such intervention is to maximize function, reduce disability, and facilitate mobility. Goal-directed treatment plans are tailored for each patient and may include a combination of modalities such as physical and occupational therapy, casting, orthoses, and surgery. Physical and occupational therapy is emphasized up to 4 to 5 years of age, whereas surgery is best between 5 and 7 years of age. Education and psychosocial development should be emphasized beginning at age 7 years through adulthood, with surgery reserved for more involved cases of contracture or bony dysplasia. In adulthood, treatment should be focused on integration into society and maximizing functional independence. Although there are many undisputed benefits of therapy, no consensus exists regarding the most beneficial modality, the age group that would benefit most, or whether continued treatment is beneficial in adulthood. Whereas the use of serial casting and tone-reducing casts has lessened, lower extremity orthoses have gained widespread acceptance with improvements in design and fabrication and have been demonstrated to help restore normal heel-toe gait. Surgical techniques such as tendon lengthening, transfer, bony osteotomy, and joint fusion are time-honored techniques that continue to be refined with current advances in the use of computerized gait analysis for preoperative planning. Further research in long-term results and outcomes measurement will be necessary to fully assess the impact of current treatment.

Bone mineralization in the affected extremities of children with spastic hemiplegia

To assess the impact of neurologic involvement on bone mineralization, dual-energy X-ray absorptiometry was used to quantitate bone mineral content (BMC), bone mineral density (BMD), fat and lean muscle mass in the limbs of 19 children with spastic hemiplegic cerebral palsy. The BMC in the affected limb was on average 26.5% lower (upper limbs) and 15.6% lower (lower limbs) than in the corresponding uninvolved limb. Lean muscle mass was reduced by 15% and BMD by 6% in the involved limbs and did not differ significantly between upper and lower limbs. The fat content of involved and uninvolved limbs did not differ. Children with poor hand function had greater reductions in BMC (39.3%), BMD (11.3%) and lean muscle mass (22.5%) than did children with better hand function. Thus, bone size and density decrease with increasing neurologic involvement, and weight bearing may slightly lessen the effect.

Managing equinus in children with cerebral palsy: electrical stimulation to strengthen the triceps surae muscle

A new therapeutic proposal for the management of equinus in children with cerebral palsy is to strengthen the calf muscles instead of weakening them surgically. Prior research indicates that in children with cerebral palsy the triceps surae muscle is weak and needs strengthening. Neuromuscular electrical stimulation (NMES) was used as an adjunct to physical therapy. A portable NMES unit with a hand-held remote switch stimulated an active muscle gait cycle. Results are discussed for four children, who showed improved gait, balance, posture, active and passive ankle range of motion, and foot alignment. The toe walkers became plantigrade and the equinovalgus posture of the foot decreased. Spasticity did not increase.

Muscle response to heavy resistance exercise in children with spastic cerebral palsy

Fourteen ambulatory children with spastic diplegia participated in a bilateral quadriceps strengthening program in an attempt to decrease the amount of knee crouch during gait. Each child exercised three times a week for six weeks using free ankle weights at a load of 65 per cent of maximum. A normal comparison group of 25 children was also tested under identical conditions. Children with cerebral palsy were significantly weaker in the quadriceps and hamstrings muscle groups than controls. Quadriceps strength increased significantly at all three angles of knee flexion as a result of the weight-training program and did not differ statistically from normal at the end of the program. Quadriceps weakness was shown to be a factor in crouch gait; restoring strength through resistance exercise may be a useful adjunct in the treatment of cerebral palsy.

Assessment of spasticity in hemiplegic cerebral palsy. II: Distal lower-limb reflex excitability and function

A clinical method for measuring the stretch reflex threshold and gain of muscles acting across the ankle joint in children with congenital hemiplegia is described. The stretch reflexes of all limbs were velocity-dependent. Hemiparetic limbs were not necessarily spastic compared with non-paretic limbs, suggesting that the term 'spastic hemiplegia' should be used more selectively and emphasis be placed on the heterogeneity of the hemisyndromes of childhood. Abnormal motor control, planning and dexterity, the hemipostures and plastic (non-electrical) muscle changes may be more important measures of impairment than reflex excitability. A general scheme for assessing reflex excitability and available treatments applicable to all types of cerebral palsy is proposed.

Assessment of spasticity in hemiplegic cerebral palsy. I. Proximal lower-limb reflex excitability

The quadriceps and hamstring muscles of 13 children with hemiplegic cerebral palsy were studied using ramp and sinusoidal stretches at three different muscle lengths. Overall, the hamstring muscles showed greater velocity sensitivity than the quadriceps, with the hamstrings having the lowest reflex velocity and frequency thresholds close to maximum knee extension. At this position, the hemiparetic hamstrings alone showed a weakly significant reduced reflex frequency threshold compared with non-paretic muscles. For all other muscle lengths, non-paretic and hemiparetic muscles displayed similar reflex thresholds when subjected to sudden, discontinuous or repetitive rhythmical, sinusoidal stretches. The number of muscles for which a reflex threshold could be established declined progressively as the angle at the knee joint approached 90 degrees of flexion. Muscles for which no reflex threshold could be demonstrated had similar velocities and frequencies of stretch as those in which a reflex was obtained.