A 7-year-old boy presents with bilateral progressive hearing loss since age 4 years. His parents report he has difficulty hearing male voices and low-pitched sounds, but hears high-pitched sounds normally. Pure-tone audiometry shows the pattern marked **A** in the diagram. On examination, a firm, non-tender swelling is noted in the anterior neck. Thyroid function tests show elevated TSH with low-free T4. Which of the following is the most likely diagnosis?

Explanation

## Why Pendred syndrome with SLC26A4 mutation and enlarged vestibular aqueduct is right The reverse-slope audiogram pattern marked **A** (low-frequency loss with preserved high frequencies) in a child with bilateral progressive SNHL, goiter, and hypothyroidism is pathognomonic for Pendred syndrome. This autosomal recessive disorder results from SLC26A4 (pendrin) mutations, causing defective iodine organification (positive perchlorate discharge test), thyroid dysfunction, and cochlear dysplasia (Mondini malformation with incomplete 2.5-turn cochlea). The enlarged vestibular aqueduct (EVA) on imaging is a hallmark feature. The reverse-slope pattern reflects apical cochlear turn damage, which encodes low frequencies. Pendred accounts for ~10% of childhood SNHL and is the most common syndromic cause of congenital deafness in iodine-sufficient regions (Cummings Otolaryngology 7e, Chapter 152). ## Why each distractor is wrong - **Ménière disease with endolymphatic hydrops**: While Ménière can present with reverse-slope SNHL due to hydrops affecting the apical turn, it is an adult-onset disorder characterized by episodic vertigo, fluctuating hearing loss, tinnitus, and aural fullness. It does NOT present with goiter or hypothyroidism, and is not the typical diagnosis in a 7-year-old with progressive bilateral SNHL and thyroid disease. - **Autosomal dominant low-frequency SNHL due to WFS1 mutation (DFNA6/14/38)**: This is the most common hereditary low-frequency SNHL, but it is autosomal dominant (not recessive), does NOT cause goiter or thyroid dysfunction, and typically presents later in childhood or adulthood. The presence of thyroid disease makes this diagnosis unlikely. - **Sudden sensorineural hearing loss with cochlear hydrops**: Sudden SNHL is typically acute in onset and affects a minority of reverse-slope cases. It does not explain the progressive bilateral presentation, goiter, or thyroid dysfunction. This diagnosis does not fit the clinical picture. **High-Yield:** Reverse-slope audiogram in a child + goiter + hypothyroidism = Pendred syndrome until proven otherwise; confirm with CT temporal bone (EVA), thyroid workup, and SLC26A4 sequencing. [cite: Cummings Otolaryngology - Head and Neck Surgery 7e, Chapter 152 (Pendred Syndrome and EVA); Dhingra Diseases of Ear Nose and Throat 7e]