Lecture 17: Genetic and Developmental Disorders Flashcards

Question

Medical Management for Neural Tube Defects

Answer 1

-detected prenatally with US scanning and serum α-fetoprotein (AFP) testing (usually occurs by 14 weeks gestation with NDTs) -tx: cesarean section is the preferred method of birth to avoid trauma to the neural sac that occurs during vaginal delivery -prenatal closure is now available by fetal surgery -prospective parents should be cautioned not to expect improvement in leg function as a result of this surgery -ventriculoperitoneal shunting is recommended in the presence of hydrocephalus; shunt revision is often required as the child grows or if the shunt becomes obstructed, infected, or separated -results in orthopaedic issues -medical management of the bowel and bladder dysfunction is of critical importance both from a medical and social standpoint: muscles of the bladder can show either spasticity or flaccidity leading to either a condition where the bladder is small and under high pressure from urine or large and stretched out and under low pressure; stool incontinence is managed most commonly by a program to regulate bowel movements using diet, timed enemas, or suppositories -prognosis: a. 85% survive into adulthood (most deaths occur before age 4) -2/3 of children with myelomeningocele and shunted hydrocephalus have intelligence that falls in the normal range -remaining 1/3 fall into the range for mental retardation, usually mild -prognosis for motor function: vary according to the level of the lesion, if functional ambulation is not present by 7-9 years of age, it is unlikely to occur

Answer 2

-previously known as congenital hip dysplasia or dislocation -common hip disorder affecting infants and children -change in name reflects the fact that DDH is a developmental process occurring either in utero or during the first year of life -can be unilateral or bilateral and occurs in 3 forms of varying severity: unstable hip dysplasia, in which the hip is positioned normally, but can be dislocated by manipulation; subluxation or incomplete dislocation, in which the femoral head of the femur remains in contact with the acetabulum but the head of the femur is partially displaced or uncovered; complete dislocation, in which the femoral head is totally outside the acetabulum -8.6-11.5/1000 live births (85% of affected infants are females) -infant positioning, both prenatally and postnatally, may affect the formation of the acetabular cup and hip stability because the acetabulum is formed as a result of contact with the femoral head -cultural customs -can affect the acetabulum, femoral head, and the relationship of the femoral head to the acetabulum -up to 12 months of age, one or more positive signs may be present -may cause Trendelenburg gait pattern

Answer 3

- Barlow maneuver: adduct with pressure dislocates hip - Ortolani maneuver: gentle hip flexion, abduction and slight traction reduce hip with click or clunk and increased hip abduction possible and only works first few weeks - Galeazzi test (Allis sign): supine, hips and knees flexed, feet flat, knee lower in dislocated side-assess unilateral hip dislocation (3 mo and up) - trendelenburg sign: weight on one leg, opposite pelvis slightly elevated is negative; weight on 1 leg pelvis drops opposite side is a positive sign

Answer 4

- clinical examination is the most important diagnostic tool - positive Ortolani’s or Barlow’s click confirms DDH in the first month of life - radiographic examination is unreliable in the infant and is used more commonly in older infants and children - tx: replacing the head of the femur into the acetabulum with no intervening soft tissue - the proper position then must be maintained for a period of time - infant placement of the hip in a position of 100° flexion and 90° abduction until the joint capsule tightens and the acetabulum is molded to assume a cup shape - can be accomplished through the use of a hip harness such as the Pavlik harness - prognosis: if dislocation is corrected, success is as high as 95% for normal hip development - satisfactory outcome of 86% with surgical reduction

Answer 5

- often PTs may be first healthcare worker to observe signs of hip pathology - an awareness of quick screening strategies for hip dysplasia is critical

Answer 6

- largest and most common group of inherited progressive neuromuscular disorders of childhood affecting all population types even animals - genetic origin and is characterized by ongoing symmetric muscle wasting without neural or sensory deficits, but with ↑’ing deformity and disability - in some forms, wasted muscles tend to hypertrophy because of connective tissue and fat deposits, giving the visual appearance of muscle strength - Duchenne’s Muscular Dystrophy (DMD) is ~ 1 in 3,500 live births - patho: knowledge of muscular dystrophies and understanding of their ↑’ing complexities escalated dramatically in the late 1980s when the protein dystrophin was identified as the causative factor in many types of MD

Answer 7

- DMD and BMD – X-linked recessive (female carrier, happens in males) - DMD much more severe than BMD - affected gene in DMD/BMD encodes messenger RNA (mRNA) for the dystrophin that is located in the muscle membrane, the sarcolemma: dystrophin is the protein that links the sarcolemma with the contractile muscle protein (actin) - lack of normal dystrophin makes the sarcolemma susceptible to damage during contraction and relaxation cycles - disruption of the muscle membrane and muscle fiber necrosis are initiated by muscle contraction, especially eccentric contraction - absence (DMD) or low levels of dystrophin (BMD) can destabilize the membrane - muscle cells are replaced by fatty tissue and CTs and contractures develop - fat cells continue to accumulate between damaged muscle fibers - CM: people with MD have muscular weakness, wasting and hypotonia, degree of severity and age of onset vary with the type of MD present - DMD - Gower's sign: places hand on thighs and walks up legs with hands until weight of trunk can be placed posterior to hip joint leads to characteristic weakness of lumbar and gluteal muscles - prognosis: varies with the type of MD present, pulmonary complications resulting from respiratory muscle dysfunction or cardiomyopathy are common sources of morbidity and mortality

Answer 8

- precautions - when people with MD become ill or injured and are on bed rest, even for a few days, they may lose many of their functional abilities - for example, a child who falls and breaks a leg and is on bed rest or immobilized may never regain the ability to ambulate - children should be encouraged to be as mobile as possible - strenuous exercise may facilitate the breakdown of muscle fibers - low-repetition maximum weightlifting, especially eccentric strengthening, is not recommended - exercise is best done in the pool where exercise is concentric - post exercise should produce only minimal fatigue with no soreness

Answer 9

- congenital muscular torticollis (CMT) - twisted neck and is a contracted state of SCM muscle producing head tilt to affected side with rotation of chin to opposite side - variety of possible causes of congenital muscular torticollis exist, but etiology remains unknown - patho: venous occlusion in addition to arterial occlusion possible explanation for some - tx: initial management involves a period of active observation for spontaneous resolution: therapy to correct positional/deformational effects is mainstay of Rx for CMT - interventions include twice daily PROM to stretch shortened muscle preceded by warm compresses, massage, and slight traction to relax the muscle before stretching; stabilization of proximal attachment of SCM and trapezius is important during ROM - positioning is important to encourage erect and midline head posture - prognosis: CMT usually resolves with conservative tx, left untreated or poorly managed, chronic, unresolved torticollis can result in persistent deformity and asymmetry of head shape and position

Answer 10

- brittle bones, rare congenital disorder of collagen synthesis affecting the bones and CT - mutations affecting genes which code for type I collagen - type I collagen is in bone, skin, and tendon: major structural protein of these tissues - wide range of clinical presentations ranging from a normal appearance with occasional fractures to severe involvement with growth retardation and long bone and spinal deformities: shortened stature is common - these children often bruise easily, and ligaments tend to show ↑’d laxity - additional clinical features may include blue or tinted (purple, gray) sclerae, thin skin, joint hypermobility, deformity of bony auditory structures with subsequent hearing impairment, scoliosis, pectus deformity, deformed teeth, a tendency toward recurrent epistaxis, excess diaphoresis, cardiovascular complications (e.g. aortic and mitral valve insufficiency, aortic dissection), and metabolic defects (e.g. ↓’d platelet aggregation)

Answer 11

- precautions: infants and children require careful handling to prevent fractures; rotational forces are contraindicated, but gently stretching in straight planes and myofascial stretching are acceptable - family education: educational material and info can be obtained from the Osteogenesis Imperfecta Foundation - family must be instructed in handling and positioning techniques - precautions should be given to avoid lifting the child under the arms or by the hands - young child should not be tossed into the air or be involved in roughhouse play - at the same time, families should be encouraged to hold and play with their child appropriately and to help the child develop interests that do not require strenuous physical activity - swimming frequently is recommended, but the child must be monitored carefully to avoid falls in the shower and pool area

Lecture 17: Genetic and Developmental Disorders Flashcards

(35 cards)