Polymicrogyria


Polymicrogyria

Description, Causes and Risk Factors:

Polymicrogyria is a developmental malformation of the human brain characterized by an excessive number of small convolutions (gyri) on the surface of the brain. Either the whole surface (generalized) or parts of the surface (focal) can be affected.

The pathology of polymicrogyria is still mysterious. It was initially considered to be a neuronal migration disorder because the cortex of the patients was thick and the cortical lamination was disturbed. Extrinsic causes of polymicrogyria comprise cytomegalovirus intrauterine infections and defects in placenta perfusion. A number of observations led to the conclusion that polymicrogyria was caused by events occuring between the 12th and 24th week of gestation.

Several papers have reported familial recurrences for polymicrogyria and in one case 12 families with multiple cases of BPP have been described. Following this descrption, two polymicrogyria loci have been localized in the human genome. The locus for bilateral perisylvian polymicrogyria has been localized to chromosome Xq28 and the locus for bilateral frontoparietal polymicrogyria to chromosome 16. It thus appears that a number of polymicrogyria cases have a genetic basis, but that polymicrogyria is genetically heterogeneous. In addition, a number of patients with deletion syndrome are sometimes affected by polymicrogyria. The chromosome 16 gene was recently identified. It encodes an orphan G protein-coupled receptor called GPR56. Mutations were found in 22 radiographically and clinically confirmed bilateral frontoparietal polymicrogyria patients from 12 pedigrees. How GPR56 dysfunction leads to the presence of polymicrogyria is currently not known.

Polymicrogyria may occur as an isolated anomaly, but more often, it occurs in conjunction with other developmental abnormalities such as microcephaly, porencephaly, hydranencephaly, arhinencephaly, or cerebral encephalocele. Association with schizencephaly is particularly common, frequently with schizencephaly in 1 hemisphere and polymicrogyria in a similar topographic location contralaterally. Polymicrogyria is often seen within or immediately adjacent to a schizencephalic cleft. Polymicrogyria may also occur in conjunction with, and in close proximity to, cortical dysplasia without balloon cells. Both abnormalities are incited during approximately the same period of cortical organization during fetal development.

The frequency of these disease is estimated to be 1 in 2500 newborns.

Symptoms:

Polymicrogyria manifests as a spectrum of clinical signs and symptoms ranging from no manifestations to severe encephalopathy or cognitive impairment. This disorder is associated with epilepsy in approximately 50% to 85% of patients. Children often present with developmental delay, spasticity, or seizures; they are also often microcephalic. Some patients with polymicrogyria go undiagnosed until they produce children with the disorder who have more severe manifestations. Retrospectively, these patients will often report some difficulty in their medical or educational history.

Diagnosis:

Polymicrogyria can be evidenced using tomodensitometry but MRI is much more powerful to reveal its morphology, topograpy and associated malformations. It is recommended to perform acquisition of thin-section saggital images though the entire brain, since different angulations of the axial images can lead to misinterpretation of the actual site of the lesion.

Genetic Counseling: Given the possible inheritance modes of PMG, a minimum recurrence risk of 25% should be given to parents. If X-linked inheritance is assumed, a recurrence risk up to 50% can even be reached in the case of a male offspring. Screening for a GPR56 mutation can be proposed in the cases of bilateral frontoparietal polymicrogyria.

Antenatal Diagnosis: In the presence of a documented GPR56 mutation in a first child, prenatal diagnosis can be proposed for furture pregnancies. No gene responsible for the other types of PMG has been identified.

Treatment:

Seizure Management: Seizure activity affects many children with the diagnosis of polymicrogyria. Priority nursing diagnoses include risk for injury and risk for aspiration. The seizures are often managed by antiepileptic drugs, and the specific drug prescribed depends on the seizure type the child is experiencing. It should be noted the seizure type may change as the child ages. These changes often occur during adolescence at which time drug therapy may need to be adjusted. Drug regimens may be altered based on the effectiveness of the seizure control and the adverse reactions the child may experience. Another consideration when starting a child on antiepileptic drugs is monotherapy versus combination therapy. Monotherapy is preferred; however, additional drugs may need to be added to achieve seizure control. When new drugs are added, the child must be monitored for the development of adverse reactions. It is important to note that most antiepileptic drugs can cause sedation and dizziness because they are central nervous system depressants. Adverse reactions may intensify with higher drug doses and/or implementation of combination therapy.

A child with polymicrogyria may experience status epilepticus which is defined as a continuous or cluster of seizures lasting longer than 20 to 30 min during which the child does not regain consciousness. This is an urgent and emergent situation. In the home or community setting, treatment options for this situation include rectal diazepam, intranasal midazolam or lorazepam, and buccal midazolam.

Children with polymicrogyria will be managed at home or in long-term care facilities. Part of the nurse's responsibility is to teach parents and other caregivers about the use of antiepileptic drugs. Some seizures are not adequately controlled with these drugs, and children may experience adverse reactions. Alternative therapies may be suggested as options to assist in the management of seizure activity including the ketogenic diet and the vagus nerve stimulator. Antiepileptic drug therapy may be minimized or discontinued if the child has a positive outcome from these alternative therapies. Nurses should be knowledgeable about these treatment modalities and educate parents as needed.

Feeding Management: Some children with polymicrogyria have difficulty in meeting their daily oral intake needs, contributing to an alteration in nutrition. This nutritional deficiency may be related to ineffective oropharyngeal muscular coordination, potentially resulting in difficulty swallowing and aspiration. Signs of altered nutrition include loss of weight, alteration in growth and development, increased length of feeding times, and oxygenation interferences related to infections and structural damage to the lungs. These children are also at risk of vomiting and development of gastroesophageal reflux.

A clinical nutritionist should be consulted to assess the adequacy of the child's diet. It is important for the child to maintain a desired body weight to avoid complications of being overweight or underweight. Types of seizures that are manifested by an increase in muscular activity can raise the caloric requirement. If the child is immobile, added weight can cause difficulty for the parent when transferring the child. In addition, obesity can contribute to the development of type 2 diabetes mellitus, coronary artery disease, respiratory dysfunction, arthritis, stroke, and certain types of cancer. Obesity can also be associated with hypertension and the potential for skin breakdown. For these reasons, weight should be monitored regularly.

If nutritional needs cannot be met with oral feedings, a gastrostomy tube may be recommended. Information to be discussed with the parents should include details of the procedure of gastrostomy tube placement including anatomical location of the tube and anticipated postprocedure appearance of the child. Advantages and disadvantages of gastrostomy feeding, side effects of tube feeding, and the mechanics of administration of the formula and medications via the feeding tube should be discussed. Typically, formula is administered by bolus feeding, continuous, or cyclic infusion. Bolus feeding is less restrictive and may not limit daily activities as significantly as continuous feeding. Education of the parent should begin prior to placement of the tube so that informed consent can be given. However, ongoing assessment of learning should continue, and information should be shared with parents in manageable doses. Positive outcomes of feeding via a gastrostomy tube include an increase in weight, an improvement in nutritional status, an improvement in growth, and decreased incidence of illness and infection. Disadvantages of gastrostomy feeding have been identified as concerns regarding performance of yet another procedure on the child as well as anxieties regarding whether there will be ample benefits of tube feeding. A gastrostomy tube can intensify feelings that the family unit is not normal because of mealtime changes related to feeding via a tube. Another concern is that enteral feeding may increase the difficulty of finding a babysitter or respite care. There will be changes in family routines and potential restriction of activity and leisure time related to the enteral feedings. For some families, the psychosocial issues are more difficult than the associated medical problems with enteral feedings. Inpatient programs such as Family Centered Service and Creating Opportunities for Parent Empowerment can be utilized and continued after discharge.

Gastroesophageal reflux disease (GERD) can occur in up to 70% of children with neuromuscular involvement such as polymicrogyria. This can occur if the child is being fed orally or through a gastrostomy tube. A Nissen fundoplication may be necessary for the relief of the symptoms of gastroesophageal reflux disease (GERD). This surgery involves the wrapping of the fundus of the stomach around the distal portion of the esophagus for the prevention of gastric reflux. Potential complications of this surgery include the breakdown of the wrap, infection, gastric distention, and retching. When a child has this procedure, it is essential to limit the volume of formula administered at any one feeding. It is also important to check the residuals prior to each feeding, and if the residuals are greater than the amount specified by the surgeon, the formula is withheld for a specified time. When there is too much volume in the stomach, it can cause the Nissen to come unwrapped.

Management of Impaired Elimination: Children with polymicrogyria are potentially at risk for multiple issues with elimination. Priority nursing diagnoses to consider include urinary retention and constipation. Neurological impairment can lead to a lack of or a delay in bladder control because maturity of the neurological system is necessary to achieve urinary continence. The neurological dysfunction in polymicrogyria may lead to the development of neurogenic bladder. Children with neurogenic bladder may have difficulty with completely emptying the bladder and may also be unable to initiate the flow of urine.

The healthcare professional should educate the parents regarding effective management of the child's urinary elimination. The goal of care should focus on effective bladder emptying and prevention of urinary tract infection. Intermittent catheterization may be necessary for bladder management to prevent urinary retention, but this increases the risk of urinary tract infection. Sterile technique is utilized in most healthcare agencies, and parents are often taught clean technique of catheterization for home management. Current literature indicates that the clean technique is acceptable because it is cost effective without significantly increasing the risk of urinary tract infection.

The neurological impairment of polymicrogyria can lead to neurogenic bowel which refers to colon dysfunction related to a neurological disease or damage. Signs and symptoms include constipation, abdominal pain, and distention. The goal of care is to promote regular bowel movements.

Management of Impaired Physical Mobility: Children with polymicrogyria frequently experience some degree of impaired physical mobility. Impaired physical mobility has been defined as limited independent movement.

Parents should be taught to monitor the child for evidence of complications of impaired physical mobility. The potential for complications will vary with each child as the degree of the impairment in physical mobility differs according to the level of neurological dysfunction. Some of the complications for which parents and healthcare professionals should assess include loss of joint mobility and muscle mass, osteoporosis, edema, skin breakdown, and infection. Others include decreased chest expansion leading to inadequate oxygenation, poor cough, respiratory infection, thrombus formation from venous stasis, constipation, and urinary retention.

Bone demineralization is a potential complication of impaired physical mobility. Proper nutrition including an adequate supply of calcium and vitamin D is essential to minimize this potential complication. Some antiepileptic medications such as Phenytoin and phenobarbital may increase the risk of bone demineralization. Children with impaired physical mobility may be required to have dual emission x-ray absorptiometry scans to monitor bone mineral density.

Assistive technology can be utilized to promote independence with activities of daily living to the highest degree possible considering the child's neurological status. Assistive technology includes equipment for positioning, mobility, and lifting. The home environment may need to be altered with ramps and widened doors and with bathroom modifications to assist with bathing and toileting. Funding for these modifications may be possible through community resources. Visitation by a home care nurse or occupational therapist would be beneficial to assess the home environment and guide implementation and evaluation.

Seating systems are important as the upright position assists in minimizing the potential complications of impaired physical mobility. The child's neurological dysfunction will guide the specific seating system, but components to consider include a headrest, seat and back inserts, anterior and lateral trunk supports, and arm and leg supports. A shoulder harness and seat belt may be needed to ensure safety if a child uses a wheelchair. Position changes while in the wheelchair should be considered to relieve pressure and prevent skin breakdown. Often, orthotics are utilized to aid in maintaining the child's functional ability. One such example is the ankle-foot orthotic, which helps to maintain the correct angle of the ankle and foot for walking or positioning while sitting in a wheelchair. The ankle-foot orthotic can also be used to prevent further deformity of the joint. Referrals to occupational and physical therapists may be needed because these professionals have the most up-to-date information on available equipment to assist with transfer, hygiene, strengthening, and positioning.

Management of Psychosocial Issues: When a child is diagnosed with a chronic condition such as polymicrogyria, the entire family is affected. The dream of having a typical child is no longer a reality, and the family will experience many changes over time. Many of these children may live into adulthood and will be cared for in the home or communities by their parents or caregivers.

Any chronic illness is stressful. An important factor to note is that parents had many responsibilities prior to the birth of a child with chronic disabilities. With the additional responsibilities that must be managed, the stress level of the family may increase and can lead to frustration and exhaustion.

Certain factors or transitional times can be very stressful for the families of children with chronic disabilities. Five such transitional events have been identified and include receiving the initial diagnosis, reorganizing tasks within the family, performing skills necessary to manage the condition, recognizing the child's failure to reach appropriate age-related milestones, and observing a change in the course of the child's illness. It is helpful for the healthcare professional to be aware of these transitional times and to intervene with encouragement and guidance to help the family adapt to the situation. Interventions include providing support options, sharing information about the disorder, helping in the management of the child, supporting families with role changes, and assisting families with normalizing their lives.

Family assessments should be completed to determine needs. Support is extremely beneficial for families to better adapt to the child's condition. Assessment of their support systems should be conducted during times of transition. This support can come from the extended family, healthcare professionals, spiritual sources, and support groups for families of children with chronic illness or disabilities. One support group that is very specific for the family of a child with polymicrogyria is the Lissencephaly Network. This is a nonprofit organization that serves children and families affected by lissencephaly and other neuronal migrational disorders including polymicrogyria. When parents understand the child's condition and potential prognosis, they are better able to realistically plan for the future. Healthcare professionals can continue to educate the parents regarding the nature and progression of this disorder to help them anticipate possible limitations and needed adaptations. Management of the child typically falls into the hands of the parents, and a positive relationship with the healthcare provider is important to enhance communication and facilitate a positive outcome for the family. A multidisciplinary approach is beneficial. The parents may need to learn about new skills, medications, use of equipment, and new technologies as appropriate. Parents also need to be educated about the child's right to an education in the least restrictive environment. Personnel from the child's school district can be helpful in giving the parents this information.

Families want to be as normal as possible while caring for their child with a disability. Several interventions can be helpful to assist the family in normalizing their fives. Assessing the families' needs in terms of support systems, coping strategies, and community resources will be helpful in planning appropriate interventions. Some of these include the distribution of tasks, how to coordinate normal routines and care of the child with the disability, and making available names of community services that may be appropriate for the family. Parents need to be told to take time for themselves to better enable them to manage the ongoing care of their child.

NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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