Oral Health in Children with Neurological Disorders

Neurodevelopmental Disorders

Diagnostic and Statistical Manual of Mental Disorders defines NDDs as a group of disorders with deficits leading to impaired functioning, with an onset in the developmental period.^2,3 NDDs encompass several disorders, including intellectual disability (ID), autism spectrum disorder (ASD) and other communication disorders, attention-deficit hyperactivity disorder (ADHD), neurodevelopmental motor disorders, cerebral palsy (CP) and specific learning disorders.^3,4 They are a significant public health burden in India.⁵ Children with NDDs suffer from different types of limitations ranging from cognitive impairment, social interaction, and communication problems, oro-motor impairments (reduced food clearanc", attention and other behavioral and sensory issues. These limitations affect their ability to carry out activities of daily living, including self-care, eating, and maintenance of oral hygiene. Many children are entirely dependent on their caregivers for these activities. Hence, oral health problems are relatively more common in these children when compared with the typically developing children.^1,6 Children with NDDs are also predisposed to nutritional deficiencies like vitamin C and vitamin D deficiency etc., which further impact their oral health. These deficiencies may occur due to several reasons such as food selectivity and selective eating (because of sensory issue", feeding and swallowing difficulties, dietary restrictions, immobility, dependency, and parental neglect.^7,8 Also, children with NDDs frequently require long-term medications or supplements, which are often administered as syrups considering the swallowing issues and difficulties in taking tablets. The continuous administration of sweetened liquid oral medicaments (syrup" adds to the risk of dental caries.^9-11 Furthermore, some of the NDDs, their comorbidities, and drugs used in the management of comorbidities directly affect the teeth, gums, and oral health (e.g., kernicterus or chronic bilirubin encephalopathy is associated with enamel hypoplasia, comorbid gastroesophageal reflux disease predisposes teeth to gastric acid, prolonged phenytoin use in comorbid epilepsy is associated with gingival hyperplasia, anticholinergic medications used for movement disorders are associated with xerostomi".^1,12,13 Access to oral healthcare services is another critical factor affecting oral health in children with NDDs.¹⁴ Recent systematic reviews and meta-analyses have revealed a higher burden of dental plaque, poor gingival status, and increased risk of dental caries in children and adolescents with intellectual disability, CP, ADHD, and ASD.^15-19 Children with CP also have an increased risk of dental malocclusion and anterior open bite, while children with ADHD are predisposed to traumatic dental injuries.^16,17

Besides the behavioral concerns (such as fear of separation and procedural stimuli like loud noises, darkness, injections, etc.) seen in typically developing children during dental care visits, children with NDDs may have several other issues.²⁰ Behavior interventions such as graduated exposure to fearful stimuli, distraction/relaxation, positive reinforcement, desensitization strategies (especially for children with ASD with sensory issue", etc., might help tackle these behavioral concerns and improve compliance.^20,21 For highly uncooperative children and adolescents with NDDs with severe behavioral issues, dental interventions/procedures under sedation or general anesthesia are effective management options.^1,22

Epilepsy

Childhood epilepsy is a global health problem, and its prevalence is nearly 6.2/1,000 population.²³ There are various epilepsy syndromes that present at different ages, and their classification is based on age at presentation, seizure type, and electroencephalographic findings. Various seizure types include generalized onset (tonic-clonic, clonic-tonic, myoclonic, absence, atonic, spasms etc.), focal onset (automatisms, autonomic, arrest, atonic, clonic, hyperkinetic etc.) and unknown onset. Children with epilepsy are at risk of dental trauma due to generalized seizure, associated teeth grinding and fall associated injuries, especially common in children with drop attacks due to myoclonic, atonic and tonic seizures. They routinely receive antiseizure medications such as phenytoin, valproate, phenobarbitone, levetiracetam etc. Long-term use of phenytoin is commonly associated with gingival overgrowth, which is partially preventable by the adjunct use of oral folic acid.²⁴ Phenytoin and carbamazepine are also associated with the alveolar bone loss.²⁵ While the dental procedure is planned, it is important that children with epilepsy should not have missed the regular dose of antiseizure medications. There is also a theoretical risk of seizure occurrence during the dental procedure, and therefore, dentists should be aware of the management of acute seizures.

Neurometabolic and Neurodegenerative Disorders (Table 2)

There are various inborn errors of metabolism and neurodegenerative disorders, which either present as episodic or a chronic progressive regression of acquired abilities. Individually, these are rare, but these disorders form a significant bulk when combined, and their management is very challenging. These disorders are very heterogeneous and usually have an underlying genetic explanation.

Broadly, neurometabolic disorders can be divided into small molecule disorders (such as urea cycle disorder, amino acidopathies, etc.), large molecule disorders (including storage disorders e.g., lysosomal storage disorder, peroxisomal disorder", disorders of cerebral energy metabolism, and miscellaneous metabolic disorders (Table 2). Based on the affected metabolic pathway, neurometabolic disorders can be classified as urea cycle disorders, fatty acid oxidation defects, organic acidemias, aminoacidopathies, peroxisomal disorders, lysosomal disorders, glycosylation disorders, disorders of cholesterol biosynthesis, mitochondrial disorders, and neurotransmitter disorders. Most of the children with these disorders either present as acute encephalopathy or chronic progressive neurological disorders with or without organomegaly (seen in many storage disorder". The major oral health concerns in children with these disorders include poor oral hygiene, pseudo-bulbar palsy, spastic jaw, oromotor dystonia, etc. These children often require special dietary management requiring frequent feeding, carbohydrate-rich diet etc., to optimize normal growth and development, which can predispose them to dental caries.²⁶ Lesch - Nyhan syndrome, a disorder of purine metabolism, needs special mention as children may often present with self-mutilation.

Neurodegenerative disorders are progressive neurological disorders occurring due to progressive loss of structure or function of neurons leading to cell death. They can be classified as gray matter degenerative disorders and white matter degenerative disorders. Gray matter disorders primarily affect neuronal cell bodies and present with epilepsy and progressive cognitive decline, for example, neuronal ceroid lipofuscinosis, while white matter disorders affect myelinated structures and present with progressive spasticity. White matter disorders can be further classified into hypomyelination disorders [such as Pelizaeus Merzbacher disease, 4 H syndrome (hypomyelination, hypogonadotropic, hypogonadism and hypodontia syndrom"] and demyelinating disorders such as metachromatic leukodystrophy. Except for hypodontia, the affected children have oral health concerns very similar to neurodevelopmental and movement disorders depending on cognitive and motor limitations.

Immune-mediated Neurological Disorders

There are various disorders under the umbrella term of immune-mediated neurological disorders. However, chronic relapsing disorders such as autoimmune encephalitis, neuromyelitis optica, and multiple sclerosis are important from a dentist point of view. These children often have episodes of recurrent neurological impairment due to flaring up of underlying immunological dysfunction, and they usually receive immunosuppressant medications. It is crucial to use adjunct antibiotics after a dental procedure in children on immunosuppression because they are prone to severe infections.

Movement Disorders

Movement disorders including tics, tremors, ataxia, dystonia, and chorea are common in various acquired and genetic neurological disorders. Dystonia deserves special attention from dentists because of the associated oral health concerns. It is characterized by abnormal involuntary twisting postures and is commonly present in a dystonic variant of CP and various genetic neurological disorders, for example, pantothenate kinase-associated neurodegeneration, neuronal brain iron accumulation etc. Dentists should be aware that dystonia can worsen with stress while a child is nervous on a dental chair. So, it is essential to give extra effort to make such a child completely relaxed and comfortable. Also, the anticholinergic medications such as trihexyphenidyl used for dystonia can cause dry mouth, which along with oro-motor dystonia, can lead to reduced food clearance and poor oral health.¹

Neuromuscular Disorders

These are heterogeneous disorders classified based on the site of involvement—muscular dystrophies and congenital myopathies with muscle localization, spinal muscular atrophies with anterior horn localization, myasthenia gravis with neuromuscular junction involvement, and genetic or acquired neuropathies with involvement of peripheral nerves. Children with these disorders often have limited physical mobility and facial or bulbar weakness resulting in drooling and swallowing difficulties. Dental malocclusions may occur in children with congenital myopathies with facial weakness. Children with hereditary sensory and autonomic neuropathy have pain insensitivity and can present with self-mutilation and pose a management challenge to the dentist team. Children with myasthenia gravis have difficulty in prolonged opening of the mouth, and therefore, the dental procedure should be brief and quick. It should be noted that oral anticholinesterase medications commonly used in myasthenia gravis increase salivation.

General anesthesia is often contraindicated in the presence of respiratory muscle weakness. The concern with general anesthesia is high in children with neuromuscular disorders and comorbid cardiomyopathy. There is also a susceptibility risk for malignant hyperthermia in some congenital myopathies and dystrophies.²⁷ Local anesthesia is the preferred choice when needed. Procaine as anesthetic agent should be avoided in children with myasthenia gravis. Table 3 lists the critical oral health problems and their predisposing factors in children with neurological disorders.