Miscellaneous ENT for INICET😍

Anterior Ethmoidal canal

Noise Induced Hearing Loss

• Safe Limit of Noise
• 85 dB for 8 hours/day
• For every 5 dB increase above 85 dB → permissible exposure time reduced by half

Sound Intensity Examples

Types of Hearing Loss

• Temporary Threshold Shift
• Due to auditory fatigue
• Recovers within 24 hours

• Permanent Threshold Shift
• Irreversible hearing loss due to increased threshold.

Pathology:

• Chronic noise exposure
• damages metabolism + ultrastructure of organ of Corti.

• Initially: Loss of outer hair cells.

• Later: Neuronal degeneration.

Features

• Outer hair cells of basal turn of cochlea affected early

• High frequencies lost first

• PTA can be normal initially

Investigations

1. Oto Acoustic Emission (OAE) – Distortion Product
• Frequency specific
• Tests outer hair cells

2. Pure Tone Audiometry (PTA) → High‑frequency audiometry
• Acoustic dip at 4000 Hz
• Progresses to down‑sloping audiogram (high frequency affection)
• Down‑sloping audiogram seen in:
• Mnemonic: PONA
• Presbycusis
• Ototoxicity
• NIHL
• Acoustic Neuroma

Management

• Prevention
• Ear plugs – 30 dB protection
• Ear muffs – 40 dB protection

• Treatment
• Hearing aid (may not be beneficial)
• Cochlear implant

Management of Ototoxicity

• Discontinue drugs

• Vestibular rehabilitation

Percentage of Hearing Impairment & Degree of Handicap

• Percentage of Hearing Impairment
• Formula:
  % = (Average hearing in speech frequencies − 25 dB) × 1.5

• Degree of Handicap
• Formula:
  Degree = ((% in better ear × 5) + (% in worse ear)) ÷ 6
• Better ear contributes 5 times more to perception

• Notes
• Hearing considered normal up to 25 dB
• Speech frequencies: 500 Hz, 1000 Hz, 2000 Hz

Sudden Sensorineural Hearing Loss (SNHL)

• Medical emergency

• Diagnostic dilemma

Definition

• Hearing loss ≥ 30 dB

• In 3 continuous frequencies

• Duration > 3 days

Etiology

• Idiopathic

• Viral infection → edema → hearing loss

Investigations

1. Tuning Fork Tests
• Rinne’s Test

2. Pure Tone Audiometry (PTA)
1. Shows severe SNHL

Management

• High‑dose steroids: 1 mg/kg/day

• If no response in 5 days → transtympanic steroids

• Antivirals

• Vasodilators

• Hyperbaric O₂

• Carbogen = 95% O₂ + 5% CO₂

• Microwick soaked in Gentamicin

Perilymphatic Fistula (PLF)

Definition

• Fistula on medial wall of middle ear → leakage of perilymph

Etiology

• Infections
• Cholesteatoma → Bony erosion → LSC fistula

• Trauma
• Iatrogenic
• Stapedotomy
• MEM
• Non-iatrogenic
• Barotrauma → Round window rupture

Clinical Features

• History of otitis media / barotrauma

• Cochlear involvement
• Sensorineural hearing loss (SNHL) / Mixed hearing loss

• Vestibular involvement
• First episode:
• Acute onset vertigo, lasts few minutes
• Subsequently:
• Pressure-triggered vertigo:
• Coughing, sneezing, Valsalva
• footplate moves
• stimulation of dilated utricle/saccule
• Tullio’s phenomenon:
• vertigo by sound
• Hennebert sign:
• vertigo + nystagmus by ear canal pressure changes
• NOTE: Seen in
• Meniere’s
• Perilymphatic fistula
• SCC dehiscence

Management

• Conservative
• Fistula closes without intervention
• Avoid pressure, straining, weight lifting

• Definitive
• Repair (if fistula does not close)

Fistula Test

• Inference:

Test Result	Interpretation / Condition
False positive fistula (Hennebert's test)	1. Seen in congenital syphilis; → due to hypermobile stapes footplate 2. Meniere disease (Tulio/Tumarkin)
False negative fistula	• Dead labyrinth • Cholesteatoma covering fistula

Preferred position for lying down

• affected ear is down → because the endolymph shift decreases stimulation.

NOTE: Hennebert's test vs Hennebert's sign

• Hennebert's test
• False positive fistula
• Seen in
• Congenital syphilis
• due to hypermobile stapes footplate
• Meniere disease

• Hennebert's sign
• Pressure-triggered vertigo + nystagmus
• NOTE: Seen in
• Meniere’s
• Perilymphatic fistula
• SCC dehiscence

Superior Semicircular Canal Dehiscence (SSCD) /

Buzzwords

• CHL

• 3rd Window effect

Etiology

• Trauma

• Congenital

Pathology

• Bone covering SSC (arcuate eminence) absent

Pathways → Symptoms

Investigations

• Pure Tone Audiometry (PTA)
• Conductive hearing loss
• Audiogram: Elevated BC thresholds (3rd window effect)
• Some AC deficit in low frequencies → Conductive HL pattern
• May show hyperacusis for bone conduction

• Tympanometry & Stapedial reflex
• Normal (middle ear intact)

• HRCT (High-Resolution CT)
• Best investigation
• HRCT shows SSC dehiscence (red arrow in diagram)



 



 

• Others
• Click-evoked VEMP (vestibular evoked myogenic potential):
• Exaggerated response
• Vestibulo-ocular reflex:
• Pronounced
• Evoked eye movements align with affected superior canal

Management

• Conservative management

• Repair (if symptoms persist)

NOTE: VEMP

Meniere's Disease

• Also called endolymphatic hydrops

• Increased endolymph in inner ear

• Usually starts in one ear, may affect both

• Common age: 20–50 years

• Equal incidence in males and females

Endolymph: Production & Absorption

• Normal Physiology: Fills membranous labyrinth

• Production:
• By stria vascularis in scala media
• Active ion transport (Na+, K+, ATPase, Na+/K+/Cl- channels)

• Absorption:
• Mainly via endolymphatic sac

Etiology

1. Imbalance
• Increased production → salt retention
• Decreased absorption → obstruction in endolymphatic sac

2. Consequence → Increased endolymph volume

3. Result → Dilation of scala media, utricle, saccule → Meniere’s

Causes of Increased Endolymph

1. Idiopathic: Primary Meniere's, unknown cause

2. Secondary:
• Viral infection
• Trauma (head/ear)
• Allergy
• Autoimmune conditions

3. Genetic:
• 10–15% genetic link
• Gene on short arm of chromosome 6

Dilation of Scala Media (Cochlear Symptoms)

1. Apex affected first → low-frequency sounds

2. Pressure ↑ in scala media → Reissner’s membrane bulges

3. Rupture of Reissner’s membrane

4. Endolymph (K+) mixes with perilymph (Na+) → toxic → hair cell damage

5. Symptoms:
• Vertigo
• Hearing loss

6. Resolution: membrane heals → pressure equalized → acute relief

Clinical Features (Cochlear involvement)

1. Vertigo
• Lasts 20 min–24 hr
• ± nausea, vomiting, diarrhea, cramps, bradycardia (vagal effect)

2. Hearing loss
• SNHL
• Fluctuating → with attacks
• Progressive → worsens with attacks
• Low frequency affected first
• Loss of fine tuning
• Recruitment (abnormally rapid loudness growth)
• Diplacusis (double hearing)

3. Tinnitus
• Ringing without external sound
• Subjective (heard only by patient)

4. Fullness in ear

Dilation of Utricle & Saccule (Vestibular Symptoms)

• Maculae distorted → defective linear acceleration detection

• Drop attacks (Tumarkin crisis):
• sudden falls, consciousness intact

Lermoyez Syndrome (Reverse Meniere’s)

• Hearing loss first → then vertigo → hearing improves post-attack
• Cause: Ductus reuniens blocked by otolith → increased endolymph → hearing loss

• Dislodged otolith → pathway opens → vertigo + restoration of hearing

Investigations

Management

Prevention

• Salt restriction

• Caffeine restriction

• Diuretics

Treatment: Acute Vertigo

• Labyrinthine Sedatives:
• Promethazine,
• Prochlorperazine,
• Cinnarizine

• Vasodilators:
• Betahistine,
• Nicotinic acid
• (Nicotine = contraindicated)

Intractable Vertigo

1. If Hearing Intact
1. Intratympanic steroids
2. Selective vestibular destruction
• Chemical labyrinthectomy:
• Gentamicin via microwick (round window) (Trans-tympanic Injection)
• Vestibulotoxic drug
• Affects: Vestibular type I >> II hair cells
• Vestibular type I hair cells are most sensitive
• Spares: Cochlear inner & outer hair cells → Hearing preserved
• Mechanism:
• Targets Na⁺/K⁺ ATPase transport channels on vestibular hair cells
• Accumulates inside → causes cell death
• Results in alleviation of vertigo without hearing loss
• Vestibular neurectomy:
• If no improvement;
• cut vestibular nerve;
• aim to preserve hearing

2. If Hearing Poor
• Total labyrinthectomy → vertigo control but total hearing loss

Other Treatments

1. Menieres Device
• Low-pressure pulses via tympanic membrane
• Redistributes and reabsorbs endolymph

2. Endolymphatic Sac Decompression
• Remove bone over sac → expansion → absorption improved
• Surgical landmark:
• Donaldson’s Line
• between lateral & posterior semicircular canals, sac lies below

 

Eye related anasthesia and N supply

Route	Target Space	Complications
Retrobulbar	Intraconal	More complications
Peribulbar	Extraconal	Fewer complications

• SET CEI

Nasociliary Nerve

• Courses along medial wall of the orbit.

• Branches
• Posterior ethmoidal nerve
• Anterior ethmoidal nerve
• Infratrochlear nerve

Innervation

• Lacrimal sac

• Inner canthus

• Lateral aspect of nose

Anterior Ethmoidal Nerve Block

• Branch of nasociliary nerve.

• Blocks distal external nasal branch.

• Clinical Use
• Provides pain relief during procedures involving:
• Lacrimal sac
• Inner canthus
• Lateral nose
• Infratrochlear Nerve Block Used in
• Dacryocystorhinostomy (DCR)

Infraorbital nerve block :

Sphenopalatine ganglion block :

• Anaesthesia of internal nose.
• Via nose
• Via greater palatine foramen (Medial to 3rd molar)

NOTE:

• Biopsy above VC → anesthetize ILN at thyrohyoid membrane

Tests for Smell

I. Smell Identification Test (SIT)

• a) University of Pennsylvania Smell Identification Test (UP SIT)
• 40 scratch & sniff questions.
• Mnemonic: University → scratch and sniff → ask questions

• b) Cross-cultural / Brief SIT / CC SIT
• Uses odours common across cultures.
• Mnemonic: All wear Briefs → cross cultural → have odour

II. Smell Diskettes

III. Sniffin’ Sticks

• Assesses degree of smell loss.

Autonomic Supply – Vidian Nerve

Formation

• Greater Superficial Petrosal Nerve (GSPN) → branch of facial nerve (parasympathetic).

• Deep Petrosal Nerve (DPN) → from sympathetic plexus around ICA.

• Fusion of GSPN + DPN → Vidian nerve

Parasympathetic Fibres

• Pass via pterygoid canal.

• Relay in sphenopalatine ganglion (SPG).

• Functions:
• Lacrimation
• Vasodilatation
• Nasal secretions
• Palatine secretions

Sympathetic Fibres

• Do not relay in SPG.

• Function: Vasoconstriction

Nasal Cycle

• Alternating vasodilatation of one nostril with vasoconstriction of the other.

• Duration: 2.5 – 4 hrs.

Nerve Injury

• Commonest RLN injured:
• Left RLN (longer course)

• Commonest cause bilateral RLN palsy:
• Surgical trauma (esp. Total thyroidectomy)

• B/L RLN Palsy
• ⛔ Posterior Cricoarytenoid → Safety muscle of VC → Abductor
• Stridor, aphonia, breathlessness (Life threatening)
• Inability to extubate

ㅤ	U/L RLN injury	SLN Injury
Presentation	• Unilateral vocal cord paralysis • Hoarseness • Post-op dysphonia • Dyspnea • Difficulty in deglutition	• ILN → Aspiration → Absent cough reflex • ELN → Low pitch
Vocal cord appearance	• RLN injury = Paramedian	• RLN + SLN injury = Cadaveric/intermediate

Types of Vocal Cord Palsy

• Complete/adductor palsy
• SLN + RLN palsy
• VC in cadaveric/intermediate position (3.5 mm from midline)

• Incomplete/abductor palsy
• RLN palsy
• Cricothyroid intact
• VC in median/paramedian position (1.5 mm from midline)

Clinical Features

• Lateralisation of VC
• Kashima → Type 2 thyroplasty
• Woodmans → cordectomy + Arytenoidectomy

Surgical Trauma

Site of injury	Nerve injured
Base of skull	Complete vagus / SLN
Carotid triangle	ILN / ELN / SLN
Upper pole of thyroid	ELN ↳ most common injured in thyroid surgery
Lower pole of thyroid	RLN ↳ 2nd most common injured in thyroid surgery ↳ Rt > Lt
Mediastinal	Left RLN ↳ also in Ortner’s / cardiovocal syndrome

Normal VC position	during
Lateral	Deep inspiration
Paramedian	Rest
Median	Phonation

During total thyroidectomy for papillary carcinoma thyroid in a thirty-six-year-old lady, the
recurrent laryngeal nerve of right side was sacrificed for oncological safety. The next day, the patient complained of breathy voice. A fiberoptic laryngoscopy on the second post-operative day showed vocal cord paralysis of the right side. What would be the positions of the right and left vocal cords in this patient, on phonation?
(A) Right cadaveric, left intermediate
(B) Right intermediate, left intermediate
(C) Right paramedian, left median
(D) Right paramedian, left paramedian

ANS

C

Treatment of Vocal Cord Palsy

Isshiki’s thyroplasty types

• Type I (Medialisation/Proximalisation)
• Thyroid cartilage pushed medially
• Indication: U/L complete (adductor palsy)

• Type II (Lateralisation)
• Thyroid cartilage pulled laterally
• Indication: B/L RLN palsy

• Type III (Shortening)
• Part of thyroid cartilage cut
• Vocal cord shortened → pitch ↓
• Indication: Puberphonia
• Shorten the long man (shortening) who has guts (Gutzmann manoevre) but female sound (Puberphonia)

• Type IV (Tightening/Tensing)
• Indication: Androphonia
• Lengthen () the short female with male voice (androphonia)

Note

• Laryngeal inlet = epiglottis + arytenoid

• ILN injury → loss of cough reflex

Galen’s anastomosis:

• Between:
• Internal laryngeal nerve (from SLN)
• Recurrent laryngeal nerve (from RLN)

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Clinical Testing

• Hypoglossus (CN 12)
• Test: ask patient to protrude tongue
• If lesion present: tongue deviates towards the affected side (ipsilateral deviation)

• Glossopharyngeal N (CN 9)
• Test: pressure on soft palate/uvula
• Also supply Glossopharyngeus

• Circumvallate papillae
• Present in the anterior 2/3rd part of the tongue
• But special sensation carried by glossopharyngeal

• Jugular canal
• Carries the glossopharyngeal nerve (IX)
• Fracture of the jugular canal
• Loss of taste sensation in the posterior 1/3rd of the tongue