What is the provisional diagnosis and expected type of hearing loss for a patient presenting with occasional discharge and deafness from their right ear for the last three years, with a small perforation in the antero-inferior quadrant of the right tympanic membrane and profuse, watery, non-foul smelling discharge?

Provisional Diagnosis: Chronic Suppurative Otitis Media (CSOM) - Inactive Mucosal Type

The provisional diagnosis is chronic suppurative otitis media (CSOM), specifically the inactive mucosal type (also called tubotympanic disease), characterized by a central perforation in the antero-inferior quadrant with intermittent watery, non-foul smelling discharge over three years. 1

Rationale for Diagnosis

• CSOM is defined as chronic inflammation of the middle ear and mastoid mucosa with a non-intact tympanic membrane and persistent ear discharge 1
• The three-year duration clearly meets the chronic criteria (≥3 months of symptoms) 1
• The antero-inferior quadrant location indicates a central (safe) perforation, which is characteristic of mucosal CSOM rather than the more dangerous attico-antral (unsafe) type that involves the posterosuperior quadrant 2
• The watery, non-foul smelling discharge distinguishes this from cholesteatoma, which typically produces scanty, foul-smelling discharge 3, 4
• The intermittent nature ("occasional discharge") suggests inactive disease with periodic exacerbations 2

---

Expected Type of Hearing Loss: Conductive Hearing Loss

This patient will have conductive hearing loss (CHL) due to the tympanic membrane perforation disrupting the normal sound conduction mechanism. 1, 2

Justification for Conductive Hearing Loss

• The intact tympanic membrane normally acts as a shield for the round window niche to create a phase difference in sound wave conduction; perforation eliminates this protective mechanism 2
• In a study of 769 perforated ears, 67.10% demonstrated pure conductive hearing loss, while only 16.10% showed sensorineural and 11.80% showed mixed loss 2
• Perforations involving the anterior or inferior half of the membrane typically show less hearing loss than posterior perforations 2
• Small central perforations generally cause mild conductive hearing loss (typically <30 dB), with larger perforations causing proportionally greater loss 5
• Single quadrant perforations produce less hearing loss than multi-quadrant involvement 2

Important Caveat

• If the patient reports vertigo, nausea, or profound hearing loss, consider ossicular chain disruption or inner ear involvement, which would indicate mixed or sensorineural components 5
• Sensorineural hearing loss in CSOM may indicate complications such as labyrinthitis or inner ear toxicity from chronic infection 4

---

Four Evaluation Processes for Hearing Loss Status

1. Pure Tone Audiometry (PTA)

Pure tone audiometry is the gold standard for quantifying and characterizing hearing loss. 1

Expected Findings in This Patient:

• Air conduction thresholds will be elevated (typically 15-40 dB for small central perforations) across frequencies, with greater loss at lower frequencies 2, 5
• Bone conduction thresholds will remain normal (≤20 dB HL), indicating intact cochlear function 1
• Air-bone gap of 15-40 dB confirms conductive hearing loss; the gap represents the degree of conductive component 1, 2
• Maximum conductive loss is typically 50-60 dB even with complete ossicular discontinuity, as bone conduction provides residual hearing 5
• For this antero-inferior perforation, expect mean hearing loss of approximately 30-40 dB, less than posterior or multi-quadrant perforations 2
• Speech reception threshold (SRT) should correlate with pure tone average (average of 500,1000,2000 Hz thresholds) 1

2. Tympanometry

Tympanometry assesses middle ear function and confirms tympanic membrane perforation. 1

Expected Findings:

• Type B tympanogram with large equivalent ear canal volume (>2.5 cm³ in adults) indicates perforation 1
• Flat tracing with no peak due to inability to create pressure changes in the middle ear 1
• Absent acoustic reflexes due to the perforation preventing pressure transmission 1
• This test is particularly useful when the tympanic membrane cannot be fully visualized due to discharge or canal edema 1

3. Tuning Fork Tests (Weber and Rinne)

Tuning fork tests provide bedside differentiation between conductive and sensorineural hearing loss. 1

Expected Findings:

• Weber test (512 Hz fork on forehead): Sound lateralizes to the affected (right) ear because conductive hearing loss masks ambient noise, making the affected ear perceive the bone-conducted sound as louder 1
• Rinne test (512 Hz fork on mastoid then at ear canal): Bone conduction > air conduction (negative Rinne) in the affected ear, confirming conductive hearing loss 1
• Rinne test on the unaffected ear: Air conduction > bone conduction (positive Rinne), which is normal 1

4. Otoscopic Examination with Pneumatic Otoscopy

Direct visualization confirms perforation location, size, and middle ear status. 1

Expected Findings:

• Small central perforation in the antero-inferior quadrant of the pars tensa 2
• Visible middle ear mucosa through the perforation, which should appear pink and healthy in inactive disease 1
• Absence of cholesteatoma (white keratinous debris) or granulation tissue 3
• Reduced or absent tympanic membrane mobility on pneumatic otoscopy due to the perforation 1
• Dry perforation at time of examination if currently inactive, or mucopurulent discharge if active 1, 2

---

Critical Clinical Pearls

• Keep the ear dry to prevent recurrent infections; water precautions are essential 5, 3
• Avoid ototoxic topical antibiotics (aminoglycosides) with non-intact tympanic membrane; use fluoroquinolone ear drops if treatment needed 1
• Refer to ENT if: perforation persists >3 months, progressive hearing loss, vertigo, facial paralysis, or suspicion of cholesteatoma 3, 6
• Surgical repair (tympanoplasty) has 80-90% success rates and is indicated for persistent perforation with documented hearing loss 7
• Duration of disease correlates with hearing loss severity: patients with 5-10 years of symptoms show mean loss of 51.15 dB versus 36.46 dB in those with <1 year 2