Pendred Syndrome
Pendred Syndrome
Pendred syndrome is an autosomal recessive disorder characterized by the combination of:
- Sensorineural hearing loss
- Thyroid dysfunction (goiter)
- Inner ear malformations
First described by Vaughan Pendred in 1896, it accounts for up to 7.5% of congenital hearing loss cases.
Key Clinical Manifestations
Auditory Features:
- Hearing Loss
- Bilateral sensorineural hearing loss
- Usually congenital or early childhood onset
- Often progressive
- May fluctuate with minor head trauma or barotrauma
- Vestibular Symptoms
- Balance problems
- Vertigo episodes
- Delayed motor development
Thyroid Manifestations:
- Goiter
- Usually develops in late childhood or early teens
- Can be asymmetric
- May be visible or palpable
- Thyroid Function
- Most patients are euthyroid
- Mild hypothyroidism in some cases
- Compensated hypothyroidism may occur
Temporal Bone Abnormalities:
- Enlarged Vestibular Aqueduct (EVA)
- Bilateral in most cases
- Key radiological finding
- Mondini Malformation
- Incomplete partition of the cochlea
- Associated inner ear anomalies
Diagnostic Approach
Initial Evaluation:
- Audiological Assessment
- Newborn hearing screening
- Complete audiological evaluation
- Serial audiometry
- Vestibular function tests
- Thyroid Evaluation
- Physical examination
- Thyroid function tests (TSH, free T4)
- Thyroid ultrasound
- Perchlorate discharge test (if available)
Imaging Studies:
- Temporal Bone Imaging
- CT scan of temporal bones
- MRI of inner ear
- Measurement of vestibular aqueduct width
- Thyroid Imaging
- Ultrasound
- Nuclear medicine studies (if needed)
Genetic Testing:
- SLC26A4 gene sequencing
- FOXI1 and KCNJ10 testing in select cases
- Family screening
Treatment Strategies
Hearing Management:
- Hearing Rehabilitation
- Early hearing aid fitting
- Cochlear implantation when appropriate
- Speech-language therapy
- Educational support
- Preventive Measures
- Avoid contact sports
- Head protection
- Careful during air travel
Thyroid Management:
- Medical Treatment
- Regular thyroid function monitoring
- Levothyroxine if hypothyroid
- Iodine supplementation if needed
- Surgical Management
- Thyroidectomy if large goiter
- Cosmetic concerns
- Compressive symptoms
Vestibular Rehabilitation:
- Balance training
- Physical therapy
- Occupational therapy
Genetics and Pathophysiology
Genetic Basis:
- Primary Gene: SLC26A4 (PDS) on chromosome 7q22.3
- Protein: Pendrin
- Inheritance: Autosomal recessive
- Other Genes:
- FOXI1 (regulatory gene)
- KCNJ10 (potassium channel)
Pathophysiology:
- Pendrin Function
- Chloride/iodide ion transporter
- Important in inner ear fluid homeostasis
- Role in thyroid hormone synthesis
- Disease Mechanism
- Impaired iodide organification in thyroid
- Disturbed endolymphatic fluid homeostasis
- Progressive damage to inner ear structures
Genotype-Phenotype Correlations:
- Variable expressivity
- Different mutations may affect severity
- Environmental factors influence progression
