Syndromic Sensorineural Hearing Loss

Etiology

The auditory system begins with the auricle, which funnels sound waves that carry mechanical energy into the external auditory canal. These waves then strike the tympanic membrane, causing it to vibrate. Vibrations are transmitted through the air-filled tympanum (middle ear), where a chain of small bones amplifies and conveys the signal toward the inner ear.

The middle ear plays a crucial role in matching the impedance between sound traveling through air and the fluid-filled cochlea. In the inner ear, hair cells convert this acoustic energy into electrochemical signals, which are transmitted to the cochlear nucleus and auditory brainstem. Hearing relies on various functions, including biochemical, metabolic, vascular, hematologic, and endocrine processes. However, the molecular structure of the auditory pathways remains poorly understood, as these pathways involve both mechanical and electrochemical processes.

Approximately half of congenital deafness is attributed to genetic causes. About 1/3 of these genetic cases are linked to disorders in other systems, resulting in syndromic SNHL. The remaining 2/3 present with isolated hearing loss, known as nonsyndromic hearing loss. Mutations in genes encoding connexin proteins are the most common genetic cause of nonsyndromic deafness. Several connexin genes associated with deafness have been identified, including those linked to autosomal dominant, autosomal recessive, and syndromic forms of hearing loss. The connexins predominantly expressed in cochlear tissues are Cx26 and Cx30.[1][2]

Congenital hearing loss is typically detected during newborn hearing screenings. However, the underlying cause remains unclear in most cases. Genetic testing can identify specific mutations, aiding in accurate prognostication of hearing loss progression and guiding therapeutic approaches. For example, infants with the Cx26 mutation generally do not experience improved hearing acuity, and this mutation is not linked to other neurological complications, making them ideal candidates for cochlear implantation. Moreover, further understanding of hearing at the molecular level could lead to future treatments, such as hair cell regeneration in the cochlea.[3]

Research in auditory neurobiology aims to uncover the genetic basis of the anatomical and physiological processes related to hearing and deafness. Given the wide range of genetic defects that can cause deafness, recognizing that no single cure exists for syndromic SNHL is essential.[4]

Epidemiology

Each year, the Center for Disease Control and Prevention (CDC) distributes the Hearing Screening and Follow-up Survey to state and territorial Early Hearing Detection and Intervention (EHDI) programs. This CDC survey collects information on infant hearing screenings, diagnostic evaluations, and enrollment in early intervention services. The information collected helps assess how effectively infants with permanent hearing loss are identified across the U.S.

According to the data collected by the CDC from states and territories for the year 2022, over 98% of newborns in the U.S. were screened for hearing loss. Permanent hearing loss was identified in over 6,000 infants born in the U.S. in 2022. The prevalence of hearing loss in 2022 was 1.7 cases per 1,000 babies screened. Some infants requiring additional testing or early intervention did not receive these essential follow-up services.

The average incidence of neonatal hearing loss in the U.S. is 1.1 per 1,000 infants, with variations among states ranging from 0.22 to 3.61 per 1,000. The prevalence rates of hearing impairment in childhood and adolescence also show variability. Based on data from comparable audiometric screening studies, the prevalence of mild hearing impairment or worse (> 20 dB) is 3.1%, while self-reported prevalence stands at 1.9%. Additionally, Hispanic Americans show a higher prevalence of hearing impairment compared to other children. Children from low-income households exhibit a higher prevalence of hearing loss compared to those from higher-income families. Genetic factors are attributed to about 23% of cases across various studies.[5]

Approximately 1 in 1,000 infants will experience severe-to-profound bilateral hearing loss (> 70 dB hearing loss). The incidence of hearing loss is 10 times higher in infants with 1 or more risk factors compared to those without risk factors. These risk factors include a family history of hereditary childhood SNHL, craniofacial anomalies, birth weight of less than 1,500 grams, hyperbilirubinemia, bacterial meningitis, an APGAR score of 0 to 4 at 1 minute or 0 to 6 at 5 minutes, and more than 5 days of mechanical ventilation. Other potential contributors include in utero exposure to TORCH infections, a group of pathogens that include Toxoplasma gondii, rubella virus, cytomegalovirus (CMV), herpes simplex virus, and other infectious agents, such as Treponema pallidum and varicella zoster virus, that may cause congenital hearing loss.[6]

Pathophysiology

The pathophysiology of syndromic SNHL varies depending on the specific syndrome. This discussion highlights some of the most common syndromes associated with syndromic SNHL, though it does not cover all possible conditions. The London Dysmorphology Database has identified 396 syndromes involving hearing loss, and the World Health Organization estimates that over 30 million children worldwide have disabling hearing loss. Deafness is typically caused by factors that affect critical stages of life, including prenatal and perinatal stages.

During the prenatal period, genetic factors and intrauterine infections, such as rubella and CMV, can lead to hearing loss. In the perinatal period, conditions such as birth asphyxia, hyperbilirubinemia, and low birth weight may contribute to hearing impairment.

Genetic hearing loss can present at birth or develop as the child grows. Syndromic congenital hearing loss is primarily categorized based on its mode of inheritance, which can be autosomal recessive, autosomal dominant, or X-linked.

Autosomal Recessive Conditions

Profound congenital SNHL is common among these syndromes. These autosomal recessive disorders also typically present earlier in life compared to many autosomal dominant entities.

Usher syndrome

Usher syndrome represents the most common form of autosomal recessive SNHL.[7] This disorder affects half of the deaf and blind population in the U.S. and is characterized by retinitis pigmentosa and SNHL, with cataracts potentially developing alongside retinitis pigmentosa in all 3 subtypes.[8] Usher syndrome has 3 subtypes, classified based on severity and progression of symptoms.

Type 1 is the most severe form, with congenital bilateral SNHL, constant vestibular dysfunction, and prepubertal retinitis pigmentosa. Type 2 presents with less severe deafness, absence of vestibular symptoms, and vision loss typically emerging around puberty. Type 3, which is much less common, is characterized by progressive hearing loss and occasional vestibular dysfunction, with vision loss developing during puberty.[9]

Pendred syndrome

Pendred syndrome presents with bilateral, moderate-to-severe, high-frequency SNHL with residual low-frequency hearing, typically presenting before speech development. Most affected individuals also develop a euthyroid goiter around 8 years of age. The condition results from a mutation in the PDS gene located on chromosome 7q, which causes a partial defect in iodide organification. Imaging often reveals inner ear malformations, particularly enlargement of the endolymphatic system.[10][11][10]

Jervell and Lange-Nielsen syndrome

Jervell and Lange-Nielsen syndrome is associated with profound SNHL and cardiac arrhythmias due to prolonged QT intervals. The syndrome stems from mutations in potassium channel genes—most commonly KCNQ1, which accounts for 90% of cases, or KCNE1—leading to conduction defects in both the inner ear and myocardium. Affected individuals often present with syncope, and electrocardiograms (ECGs) reveal large T waves and marked QT prolongation.

QT prolongation without SNHL may be inherited dominantly or recessively, with the more common dominant variant being Romano–Ward syndrome.[12] Malignant arrhythmic events can lead to sudden death at a young age, but β-blocker therapy lowers the mortality rate from 71% to 6%.

Autosomal Dominant Disorders

Autosomal dominant syndromes associated with hearing loss exhibit a diverse range of presentations and can manifest at various stages of life. These conditions typically show a variable expression of symptoms, even within the same family, due to the dominant inheritance pattern.

Waardenburg syndrome

Waardenburg syndrome accounts for 3% of childhood hearing loss and represents the most common autosomal dominant form. The condition involves bilateral or unilateral SNHL, pigmentary abnormalities, and characteristic craniofacial features. Pigmentary findings include heterochromia irides (differently colored irises), a white forelock, premature graying, vitiligo, and depigmentation of the stria vascularis within the cochlea. Craniofacial features include dystopia canthorum (widely spaced medial canthi), a broad nasal root, and synophrys (confluent eyebrows).[13][14]

Waardenburg syndrome includes 4 distinct subtypes. Type I presents with heterochromia iridis, a white forelock, patchy skin hypopigmentation, and dystopia canthorum. About 20% of these individuals have congenital SNHL. Additional features may include a pale blue iris, broad nasal bridge, synophrys, square jaw, hypoplastic nasal alae, and a persistent metopic suture. Type II shares similar pigmentary traits but lacks dystopia canthorum. Up to 50% have SNHL. Type III, or Klein–Waardenburg syndrome, includes the features of type I with the addition of microcephaly, skeletal deformities, and intellectual disability.[15] Type IV, also known as Shah–Waardenburg syndrome or Waardenburg–Hirschsprung disease, mirrors type I but includes features of Hirschsprung disease, such as aganglionic megacolon.[16]

Treacher Collins syndrome

Treacher Collins syndrome, also referred to as "mandibulofacial dysostosis," involves facial anomalies that include malar and mandibular hypoplasia, downward-slanting palpebral fissures, coloboma of the lower eyelids, malformed external ears or canals, dental malocclusion, and cleft palate. Around 30% of cases involve conductive hearing loss, though SNHL or vestibular dysfunction can also occur. External auditory canal atresia and ossicular chain anomalies are frequent findings. The incidence is approximately 1 in 50,000, with 50% of cases arising from de novo mutations.[17][18][19] Most cases are caused by mutations in the TCOF1 gene on chromosome 5q32–33.1, which encodes a protein called "treacle."[20] Less commonly, mutations in POLR1D and POLR1C contribute to Treacher Collins syndrome, affecting RNA polymerase subunits involved in rRNA transcription.[21]

Stickler syndrome

Stickler syndrome is an autosomal dominant disorder of collagen connective tissue involving ophthalmic, orofacial, auditory, and articular manifestations.[22] Common features include cleft palate, micrognathia, myopia, retinal detachment, cataracts, and a marfanoid habitus. Diagnostic criteria require a congenital vitreous anomaly and at least 3 of the following: early-onset myopia (before 6 years of age), rhegmatogenous retinal detachment or perivascular pigmented lattice degeneration, joint hypermobility measured by the Beighton score, SNHL confirmed by audiometric testing, or midline clefting.[23]

The condition results from mutations in COL2A1, COL11A1, and COL11A2, which encode for types II and XI collagen subunits.[24][25][26]] Type 1 Stickler syndrome is caused by COL2A1 mutations and features progressive myopathy, retinal detachment, vitreoretinal degeneration, and a characteristic “membranous” vitreous phenotype. Palate anomalies are frequently observed, and hearing is typically normal or only mildly affected. Type 2 stems from COL11A1 mutations and presents with moderate SNHL but lacks retinal detachment. Ocular abnormalities are absent due to limited gene expression in the vitreous.[27]

Type 3 involves COL11A2 mutations and also lacks ocular findings. Autosomal recessive variants that resemble type 3 clinically have been linked to mutations in COL9A1 and COL9A2, though palate deformities are uncommon. These individuals often develop moderate to severe SNHL during childhood but typically do not exhibit the vitreous changes seen in type 1.

Branchio-oto-renal syndrome

Branchio-oto-renal (BOR) syndrome, also known as Melnick–Fraser syndrome, accounts for approximately 2% of congenital hearing loss cases.[28][29][30] The condition affects the branchial arch system, auditory structures, and renal development, with anomalies observed in the outer, middle, and inner ear. External findings include preauricular pits or tags (82%), auricular malformations (32%), microtia, and canal stenosis. Middle ear anomalies can involve an absent oval window, facial nerve dehiscence, a narrowed middle ear cleft, and abnormal ossicular morphology. Inner ear abnormalities include cochlear dysplasia and hypoplasia, enlarged vestibular aqueduct (EVA), and lateral semicircular canal irregularities.

Hearing loss occurs in up to 90% of cases—commonly a mixed loss (50%), but occasionally isolated conductive (30%) or sensorineural (20%). Approximately 35% of individuals have severe hearing loss, and 25% experience progressive decline. Branchial anomalies are found in about 50% of affected individuals, often presenting as lateral cervical fistulae, sinuses, or cysts. Renal involvement occurs in roughly 65% of patients and may present as agenesis (most commonly), hypoplasia, or dysplasia. Less frequent features include lacrimal duct aplasia, a short palate, retrognathia, and benign intracranial tumors.

The most frequently implicated gene is EYA1, located on chromosome 8q13.3, although EYA2 and EYA3 have also been associated with BOR syndrome.[31][32] Additional causative genes include SIX1 and SIX5, both of which belong to the same developmental pathway.[33][34]

Neurofibromatosis type 2

This condition is characterized by bilateral vestibular schwannomas and other tumors, including meningiomas, optic gliomas, ependymomas, and spinal tumors.[35] Children of affected individuals have a 50% risk of developing neurofibromatosis type 2. The NF2 gene, located on chromosome 22q12.17, encodes the tumor suppressor protein Merlin (Schwannomin), which plays a role in correcting F-actin cytoskeletal defects in schwannomas.[36]

Key clinical features include bilateral vestibular schwannomas, cafe-au-lait spots, and subcapsular cataracts. Hearing loss, typically high-frequency and sensorineural, is the most common initial symptom of neurofibromatosis type 2.[37][38] Other symptoms may include facial nerve paresis or paralysis, tinnitus, vertigo, and balance issues. Bilateral vestibular schwannomas are present in up to 95% of affected individuals, though symptoms typically emerge in early adulthood.

Osteogenesis imperfecta

Osteogenesis imperfecta is marked by fragile bones, blue sclera, joint hyperelasticity, and hearing loss, which may be conductive, sensorineural, or mixed. This condition is associated with mutations in the COLIA1 gene on chromosome 17q and the COLIA2 gene on chromosome 7q. A subtype, Van der Hoeve syndrome, is characterized by progressive hearing loss that begins in early childhood.[39]

Otosclerosis

Otosclerosis, or otospongiosis, occurs when spongy bone tissue grows around the stapes footplate, leading to ossicular fixation and conductive hearing loss. This type of hearing loss usually presents in early adulthood.[40]

X-Linked Genetic Disorders

X-linked syndromes associated with hearing loss are characterized by a variety of systemic features that often have more severe manifestations in male individuals. Female individuals may be asymptomatic carriers or experience milder or atypical symptoms, depending on the presence of factors that influence gene expression, such as X-inactivation.

Alport syndrome

Alport syndrome affects basement membrane collagen in the kidney and inner ear, leading to renal failure and progressive SNHL.[41] Caused by a mutation in COLIA5, which encodes a form of type V collagen, Alport syndrome almost exclusively affects male individuals, though a much milder form can be seen in female individuals.

Norrie syndrome

Norrie syndrome is characterized by ocular symptoms, progressive SNHL, and mental retardation. Patients are born blind and develop sensory hearing loss in adolescence. The hearing loss in Norrie disease, shown in a genetically altered knockout mouse, involves dysfunction of the stria vascularis, while other inner ear structures remain intact in the early stages.[42]

Otopalatodigital syndrome

Otopalatodigital syndrome is associated with hypertelorism and craniofacial deformities, including a flattened midface, small nose, and cleft palate. Patients also present with short stature, digital anomalies such as varying finger and toe lengths, space between digits, and conductive hearing loss due to ossicular abnormalities.

History and Physical

Historical factors to review include any family history of hearing loss, eye abnormalities, or congenital heart disease. Prenatal and perinatal histories should cover TORCH infections, gestational diabetes, maternal hypothyroidism, and exposure to drugs, alcohol, or tobacco during pregnancy.

A thorough head and neck examination should evaluate for microtia, aural atresia, periauricular skin tags, anterior cervical pits, and ocular findings such as altered visual acuity, abnormal iris pigmentation, or altered intercanthal distance. Clinicians should check for cleft lip or palate, skull asymmetry or macrocephaly, and digital anomalies. Any areas of pigmentation abnormalities, including café au lait macules, should be documented. Even with a normal otoscopic examination, middle ear fluid should still be ruled out. Additional attention should be directed toward identifying morphologic abnormalities or systemic involvement affecting the heart, lungs, kidneys, or liver.

Various physical findings are associated with congenital hearing loss.[43] Distinctive external ear features that frequently align with known syndromes presenting with SNHL include the following:

• Auricular deformity: Treacher Collins syndrome, Goldenhar syndrome (oculo-auriculo-vertebral spectrum)[44][45][46]
• External canal atresia or stenosis: Treacher Collins syndrome, Goldenhar syndrome
• Preauricular pits: BOR syndrome [47]
• Preauricular skin tags: Goldenhar syndrome
• Enlarged vestibular aqueduct: Pendred syndrome, Kabuki syndrome, Turner syndrome, Opitz-Frias syndrome [48]
• Lop ears: Trisomy 21, otopalatodigital syndrome
• Cup ear: Pierre Robin sequence [49]
• Microtia: Treacher Collins syndrome, Goldenhar syndrome, 1st branchial cleft syndrome, Möbius syndrome, Duane syndrome

Ocular anomalies may develop alongside syndromic SNHL in the following settings:

• Cataracts: Congenital rubella
• Coloboma: CHARGE association (coloboma of the iris, heart deformities, choanal atresia, retarded growth, genital and ear deformities)
• Dystopia canthorum, heterochromia irides: Waardenburg syndrome [50]
• Keratitis: Cogan syndrome
• Ocular palsy: Duane syndrome
• Retinal atrophy: Cockayne syndrome
• Retinitis pigmentosum: Usher syndrome
• Retinal degeneration: Alström syndrome [51]
• Congenital blindness, pseudotumor retinae: Norrie syndrome

Skin, hair, and iris abnormalities, together with SNHL, can reflect broader genetic conditions, as in the following:

• Pigmentary abnormalities of skin, hair, and iris: Albinism, piebaldness, Waardenburg syndrome, Tietze syndrome
• Ectodermal dysplasia: Ichthyosis
• Hypopigmentation: Albinism
• Lentigines: LEOPARD syndrome (lentigines, ECG abnormalities, ocular hypertelorism, pulmonary stenosis, abnormalities of genitalia, retardation of growth, and deafness) [52]
• White forelock: Waardenburg syndrome

Cardiac anomalies may present with syndromic SNHL, as in the following:

• Widened QRS or bundle branch block, pulmonary stenosis: LEOPARD syndrome
• Prolonged QT: Jervell and Lange-Nielsen syndrome [53]
• Mitral insufficiency: Forney syndrome

Renal and auditory manifestations can cooccur in the following conditions: 

• Glomerular kidney disease: Alport syndrome, Hermann syndrome, Fanconi anemia, BOR syndrome
• Malformation: Goldenhar syndrome

Dental abnormalities can help pinpoint syndromic patterns in hearing loss, as in the following:

• Abnormal dentin: Osteogenesis imperfecta[54]
• Pegged (Hutchinson) incisors: Congenital syphilis

Endocrine or metabolic abnormalities may occur with syndromic deafness in the following conditions:

• Thyroid goiter: Pendred syndrome
• Hypogonadism: Alström syndrome
• Obesity: Laurence-Moon-Biedl syndrome
• Mucopolysaccharidosis: Hunter, Hurler, Sanfilippo, and Morquio syndromes
• Diabetes mellitus: Alström, Hermann syndromes
• Ovarian dysgenesis: Perrault syndrome
• Thymus agenesis: DiGeorge syndrome [55]

Neurologic abnormalities may accompany hearing loss in the following conditions:

• Ataxia: Spinocerebellar degeneration
• Epilepsy: Hermann syndrome
• Peripheral neuropathy: Flynn-Aird syndrome [56]
• Polyneuropathy: Refsum disease

Skeletal changes provide strong clues to the syndromic nature of congenital SNHL, as in the following cases:

• Dwarfism: Achondroplasia, Cockayne syndrome
• Fusion of cervical vertebrae: Klippel Feil syndrome
• Limb deformities: Osteogenesis imperfecta, Hurler syndrome
• Scoliosis, elongated limbs: Marfan syndrome [57]
• Syndactyly: Apert syndrome
• Skeletal and joint abnormalities, myopia, vitreoretinal degeneration: Stickler syndrome

Craniofacial features, as in the following conditions, offer some of the clearest syndromic signals in congenital hearing loss:

• Syndactyly: Apert syndrome
• Acrocephaly (tower skull): Apert syndrome
• Branchial fistulas: BOR syndrome
• Cleft palate, small mandible: Pierre Robin sequence
• Cranial synostosis, midface hypoplasia: Crouzon syndrome
• Characteristic facies (malar and zygomatic hypoplasia, small jaw), cleft palate, eyelid colobomata, external and middle ear anomalies: Treacher Collins syndrome
• Ocular or auricular anomalies: Goldenhar syndrome [58]

The neonatal examination plays a crucial role in the early identification of physical markers that point to specific syndromic causes of hearing loss. Incorporating data from this evaluation step into the diagnostic process helps refine the differential diagnosis and guide further testing.

Evaluation

Early detection of hearing impairment plays a critical role in improving outcomes. Universal newborn hearing screening programs are available in all 50 states, with recommendations to conduct screening within the 1st 3 months of life. The American Academy of Pediatrics has developed the Early Hearing Detection and Intervention program to ensure that screenings are completed by 1 month of age, hearing loss is diagnosed by 3 months, and early intervention services are initiated by 6 months.

The initial screening tests typically involve auditory brainstem response (ABR) or otoacoustic emissions (OAE) testing. If an infant does not pass the newborn hearing screening, additional diagnostic testing is recommended to confirm the presence of hearing loss. Evaluations may include magnetic resonance imaging (MRI) or computed tomography (CT) of the temporal bones and the internal auditory canal.

Historically, CT scans of the temporal bones were the preferred initial imaging method. Advantages of CT scans include high-resolution images with 1-mm slices, which allow for excellent visualization of bone anatomy, ossicles, and the inner ear. CT scans can also identify potentially surgically reparable causes of SNHL, determine the less dysplastic ear (which may be better for auditory habilitation), and reveal common findings such as enlarged vestibular aqueduct and Mondini malformation, which are often associated with Pendred syndrome.

However, recent evidence suggests that MRI may provide certain advantages, including higher soft tissue contrast. The timing of imaging and the specific patients who should undergo these evaluations remain topics of debate.[59][60] In some cases, renal ultrasonography may be necessary.

In cases of syndromic hearing loss, further workup often depends on the associated clinical findings. A genetics consultation is typically recommended as part of the assessment, with genetic testing for mutations in the gap junction β2 gene (GJB2), which encodes connexin 26, playing a key role in evaluating patients with bilateral severe to profound SNHL.

Hearing tests for other family members should also be considered. While routine laboratory testing in children with bilateral SNHL has limited diagnostic value, serological tests may be considered to assess past or present infections. Specific historical or physical examination findings may warrant further testing. For example, an ECG may be indicated in the presence of a family history of syncope, and thyroid function tests may be necessary if symptoms suggest hypothyroidism. A recent study found that 57% of children with syndromic hearing loss had significant ophthalmologic findings, making it advisable to refer children with severe to profound SNHL for an eye examination. Electrooculography may help identify retinitis pigmentosa in these cases.

Additional laboratory studies may be considered in the workup of syndromic SNHL, each offering insights into potential underlying conditions. A complete blood count with differential can help identify hematologic abnormalities, which may be relevant in conditions like leukemia or anemia that could contribute to hearing loss. Chemistries, including blood sugar levels, blood urea nitrogen, creatinine, and urinalysis, provide important information about metabolic or renal dysfunction that may cooccur with syndromic SNHL, especially in conditions like Alport syndrome.

Fluorescent treponemal antibody absorption (FTA-ABS) testing is useful for identifying syphilis, a potential contributor to congenital hearing loss, while specific immunoglobulin M assays for toxoplasmosis, rubella, CMV, and herpesvirus help detect infectious causes that may affect the auditory system. An autoimmune panel, including erythrocyte sedimentation rate, antinuclear antibody, rheumatoid factor, complement levels, and specific tests like Raja cell studies, Western blot for anti-68 KD autoantibody, and circulating immune complexes, is essential for detecting autoimmune diseases that could present with syndromic hearing loss as part of a broader systemic involvement.

Shortly after birth, several audiology tests may be performed to assess hearing function. These tests include auditory brainstem response, audiometry, tympanometry, acoustic reflex threshold measurement, and otoacoustic emissions. Each of these assessments plays a role in detecting hearing impairment early, ensuring timely intervention and management.

Testing for TORCH infections—Toxoplasma gondii, rubella virus, CMV, herpes simplex virus, and Treponema pallidum—should be considered in certain cases. If a TORCH infection is confirmed, management strategies such as antiviral therapy, immunoglobulin treatment, and supportive care may be considered, depending on the specific pathogen.[61][62][63]

Chromosomal abnormalities, if suspected, should be should be thoroughly investigated. Trisomy 13 (Patau syndrome), trisomy 18 (Edwards syndrome), trisomy 21 (Down syndrome), and trisomy 22 are chromosomal conditions commonly associated with hearing loss. If a genetic cause of congenital SNHL is confirmed, a personalized management plan should be developed, often involving genetic counseling for the family to understand inheritance patterns, recurrence risks, and potential impacts on other family members.

Treatment / Management

The management of syndromic hearing loss varies based on the degree, onset, and laterality of the hearing impairment. Medical care may address otitis media or other middle ear abnormalities. Hearing amplification options should be considered, including hearing aids in the first few months of life. Cochlear implants are often indicated in cases of bilateral severe-to-profound SNHL.[64][65] Bone-anchored hearing aid (BAHA) implants may also be appropriate. Hearing assistive devices, like frequency modulation trainers, volume control telephone devices, closed captions, and signaling devices for visual cues, may also be useful for improving communication and safety. Other emerging treatments, such as middle and inner ear devices, may be available in the future.[66][67](A1)

Differential Diagnosis

When evaluating syndromic SNHL, a broad range of systemic conditions that may contribute to or mimic hearing impairment should be considered. These conditions, which include the ones below, can complicate the diagnosis and management, making a thorough evaluation essential for accurate treatment planning.

• Accelerated coagulation  
• Arteriosclerosis  
• Diabetes mellitus  
• Hypothyroidism  
• Leukemia  
• Macroglobulinemia  
• Polycythemia vera  
• Sludging due to hyperviscosity

Accurate identification of the underlying cause in cases of syndromic SNHL is crucial for tailoring appropriate management strategies. Excluding other systemic conditions through a comprehensive differential diagnosis helps ensure timely and effective interventions, improving long-term patient outcomes.

Prognosis

Early diagnosis and treatment significantly improve the prognosis for congenital hearing loss, even in severe or profound cases. Timely aural rehabilitation can help minimize the impact of hearing loss on speech and language development.

Complications

Patients with syndromic SNHL often face a range of physical, psychological, and sensory challenges. Regular follow-up appointments with physicians, audiologists, and speech and language pathologists are essential for reassessing diagnoses, promoting hearing aid use, and creating effective rehabilitation plans for speech, language, and learning. The prognosis depends on hearing restoration potential, cognitive abilities, and access to educational programs. Complications vary based on individual circumstances.