(PP1006) Audiological Manifestations of Dravet Syndrome

Dravet Syndrome (DS) is an uncommon form of genetic (SCN1A mutation) epilepsy characterized by progressive cognitive impairment and developmental delays, motor dysfunction, and seizure activity which begins between five and eight months of age. Currently, there is a lack of literature concerning auditory findings in these individuals. The case presented here is from a seven-year-old female with DS who was referred for a central auditory processing evaluation; behavioral and electrophysiological findings will be discussed.

Summary: 

Background

Dravet Syndrome (DS) is an uncommon form (incidence of 1 in 15,700-40,900) of genetic (80% of those with DS have SCN1A mutation) epilepsy (Wirrell et al., 2017). DS is characterized by seizure activity which begins between five and eight months of age followed by progressive cognitive impairment and developmental delays. Often seizures can be triggered by stress or hyperthermia. As these patients age, symptoms of abnormal gait, hypotonia, poor dexterity and coordination, and intellectual disability appear which were not present prior to the seizures. The EEG in older children is typified by general slowing and imaging (MRI) can be normal or show signs of general atrophy and hippocampal sclerosis. DS is a life-long disorder which requires a regimen of anticonvulsant drugs to control seizure activity, but surgical interventions have not shown to be successful. Children with DS will often be dependent on caregivers for their entire lives (Wirrell et al., 2017). Currently, there is a lack of literature concerning auditory findings in these individuals and the suggested DS team does not include audiology.

Case

This patient has current diagnoses of DS (SCN1A), IgA deficiency (immune deficiency), and asthma. She has had recurrent otitis media and had her third set of PE tubes placed in January 2019 (currently extruded). Current medications included Depakote and potassium bromide (anticonvulsants) with Diastat as a rescue drug for DS-related seizures and Flovent for asthma.

Mom’s concerns about the child’s listening included: asking for repetition, poor rhythm, selective hearing, difficulty hearing in noise, poor listening attention, difficulty with reading comprehension & math word problems, trouble with multi-step directions, poor auditory memory. The patient has an existing IEP at school, and receives tutoring, OT, PT, and SLP services through the school.

Audiometry indicated thresholds within normal limits with fair word recognition. Tympanometry was normal, but all MEMRs were absent; DPOAEs were present 3-10kHz bilaterally. The patient had a persistent abnormally large right-ear advantage on dichotic and monaural low-redundancy tasks; she could hum but not label during temporal patterning. These findings are in line with an integration pattern of central auditory processing disorder as per the Bellis-Ferre model.  Results from neurodiagnostic ABR, MLR, P300, and cABR are forthcoming.

Discussion
This child’s test results are consistent with reports of deficits in integration circuitry, e.g., visual-motor, auditory-motor (Chieffo et al., 2011), which can be attributed to reduced white matter volume (Perez et al., 2014) or possibly cerebellar dysfunction present in DS (Chieffo et al., 2011; Kalume et al., 2007). According to AAA (2010) and ASHA (2005) definitions of CAPD, it would not be appropriate to diagnose this child with CAPD as the deficits noted arose from a distinct disorder (DS), however, it is possible formal and informal integration-specific therapies may benefit her. Increasing audiologist awareness and knowledge of DS will help us better serve these patients and aid in improving their quality of life.