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Acute Sinusitis | Sinusitis | Nose | Otorhinolaryngology (Ear Nose Throat / E.N.T) | 4th Year (Fourth Year) | MBBS | Detailed Free Notes

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1. EXAM-READY DEFINITION

  • Acute sinusitis (acute rhinosinusitis) is an acute inflammatory condition of the mucosal lining of one or more paranasal sinuses, usually following a viral upper respiratory tract infection, with symptom duration less than 4 weeks.

  • The condition almost always involves both the nasal cavity and paranasal sinuses, hence the preferred term acute rhinosinusitis.

One-Line University Answer

Acute sinusitis is acute inflammation of the paranasal sinus mucosa lasting less than four weeks, commonly following viral URTI.

2. TERMINOLOGY & CLASSIFICATION CONTEXT (HIGH-YIELD)

2.1 TERMINOLOGY

  • Sinusitis → inflammation of sinuses

  • Rhinosinusitis → combined inflammation of nose and sinuses (correct term)

2.2 CLASSIFICATION OF RHINOSINUSITIS (VIVA FAVORITE)

A. BASED ON DURATION

  • Acute: < 4 weeks

  • Subacute: 4–12 weeks

  • Chronic: > 12 weeks

  • Acute on chronic

B. BASED ON ETIOLOGY

  • Viral (most common)

  • Bacterial

  • Fungal (rare in acute, except immunocompromised)

C. BASED ON SINUS INVOLVEMENT

  • Maxillary sinusitis

  • Frontal sinusitis

  • Ethmoid sinusitis

  • Sphenoid sinusitis

  • Pansinusitis

Exam Pearl

Maxillary sinus is the most commonly involved sinus in acute sinusitis.

3. EPIDEMIOLOGY (EXAM-RELEVANT)

3.1 INCIDENCE

  • Very common condition

  • One of the most frequent reasons for antibiotic prescription

3.2 AGE GROUP

  • All age groups

  • Children:

    • Ethmoid sinusitis common

  • Adults:

    • Maxillary and frontal sinusitis common

3.3 RISK FACTORS

  • Viral URTI

  • Allergic rhinitis

  • Deviated nasal septum

  • Nasal polyps

  • Smoking

  • Swimming/diving

  • Dental infections (maxillary sinus)

4. APPLIED ANATOMY (CORE ENT EXAM SECTION)

4.1 PARANASAL SINUSES

  • Maxillary

  • Frontal

  • Ethmoid

  • Sphenoid

4.2 OSTEOMEATAL COMPLEX (VERY HIGH-YIELD)

  • Located in middle meatus

  • Drains:

    • Maxillary sinus

    • Frontal sinus

    • Anterior ethmoid sinuses

Exam Line

Obstruction of the osteomeatal complex is the key event in the pathogenesis of acute sinusitis.

4.3 WHY MAXILLARY SINUS IS MOST COMMONLY INVOLVED

  • Ostium located high on medial wall

  • Gravity-dependent drainage is poor

  • Close relationship with upper teeth roots

5. ETIOLOGY (STEP-WISE, EXAM-ORIENTED)

5.1 PRIMARY CAUSE

  • Viral upper respiratory tract infection

5.2 SECONDARY BACTERIAL INFECTION

  • Occurs when:

    • Mucociliary clearance is impaired

    • Ostium becomes obstructed

5.3 COMMON BACTERIAL ORGANISMS

  • Streptococcus pneumoniae

  • Haemophilus influenzae

  • Moraxella catarrhalis

  • Staphylococcus aureus (less common)

5.4 OTHER ETIOLOGICAL FACTORS

  • Allergic rhinitis

  • Dental infections (maxillary sinusitis)

  • Nasal trauma

  • Foreign bodies (children)

  • Barotrauma (diving, flying)

6. PATHOGENESIS (VERY HIGH-YIELD, STEP-BY-STEP)

6.1 INITIATING EVENT

  • Viral URTI → nasal mucosal inflammation

6.2 SEQUENCE OF EVENTS

  1. Viral infection causes mucosal edema

  2. Edema blocks sinus ostia

  3. Ventilation of sinus decreases

  4. Negative pressure develops

  5. Transudation of fluid into sinus

  6. Mucociliary clearance impaired

  7. Secondary bacterial infection

  8. Pus formation within sinus

6.3 KEY PATHOGENETIC TRIAD

  • Ostial obstruction

  • Impaired mucociliary clearance

  • Infection

Exam Line

Acute sinusitis develops due to obstruction of sinus ostium, leading to retained secretions and secondary infection.

7. MORPHOLOGY / PATHOLOGY

7.1 GROSS PATHOLOGY

  • Hyperemic sinus mucosa

  • Edematous lining

  • Accumulation of:

    • Serous fluid (early)

    • Purulent exudate (later)

7.2 MICROSCOPIC FEATURES

  • Acute inflammatory infiltrate

  • Predominantly neutrophils

  • Mucosal edema

  • Dilated blood vessels

8. CLINICAL FEATURES — SYMPTOMS (WITH LOGIC)

8.1 NASAL SYMPTOMS

  • Nasal obstruction

  • Purulent nasal discharge

  • Post-nasal drip

8.2 FACIAL PAIN / PRESSURE (VERY IMPORTANT)

  • Maxillary sinus:

    • Cheek pain

    • Upper toothache

  • Frontal sinus:

    • Forehead pain

    • Worse in morning

  • Ethmoid sinus:

    • Pain between eyes

  • Sphenoid sinus:

    • Deep retro-orbital headache

Exam Line

Facial pain aggravated by bending forward is characteristic of acute sinusitis.

8.3 SYSTEMIC SYMPTOMS

  • Fever

  • Malaise

  • Headache

8.4 OLFACTORY DISTURBANCE

  • Hyposmia

  • Anosmia (temporary)

9. SIGNS ON EXAMINATION

9.1 ANTERIOR RHINOSCOPY

  • Congested nasal mucosa

  • Purulent discharge in middle meatus

  • Edematous turbinates

9.2 POSTERIOR RHINOSCOPY / ENDOSCOPY

  • Pus trickling from sinus ostium

  • Better visualization of osteomeatal complex

9.3 TENDERNESS (EXAM FAVORITE)

  • Maxillary sinus tenderness

  • Frontal sinus tenderness

10. SPECIAL CLINICAL TYPES (SHORT NOTES FAVORITE)

10.1 ACUTE MAXILLARY SINUSITIS

  • Most common

  • Cheek pain

  • Toothache

  • Dental origin possible

10.2 ACUTE FRONTAL SINUSITIS

  • Severe headache

  • Risk of intracranial complications

10.3 ACUTE ETHMOID SINUSITIS

  • Common in children

  • Risk of orbital complications

10.4 ACUTE SPHENOID SINUSITIS

  • Rare

  • Deep headache

  • Late diagnosis

11. COMPLICATION TENDENCY (INTRODUCTORY)

  • Orbital cellulitis

  • Subperiosteal abscess

  • Meningitis

  • Brain abscess

(Complications will be discussed in detail in later parts)

12. DIAGNOSIS — INTRODUCTION

  • Mainly clinical

  • Imaging reserved for:

    • Complications

    • Non-responding cases

(Investigations, management, complications, OSCE, viva, examiner traps in PART 2 & PART 3)

Written And Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change MBBS 4th Year (Fourth Year / Professional) Otorhinolaryngology (ENT) Free Material

13. INVESTIGATIONS (STEP-WISE, EXAM-ORIENTED)

13.1 CLINICAL DIAGNOSIS (MOST IMPORTANT)

  • Acute sinusitis is primarily a clinical diagnosis

  • Diagnosis based on:

    • Recent URTI

    • Facial pain/pressure

    • Purulent nasal discharge

    • Nasal obstruction

  • Investigations are not routinely required in uncomplicated cases

Exam Line

Acute sinusitis is mainly diagnosed clinically; investigations are reserved for complications or non-responding cases.

13.2 NASAL ENDOSCOPY

  • Allows:

    • Direct visualization of pus in middle meatus

    • Assessment of osteomeatal complex

  • Indications:

    • Diagnostic uncertainty

    • Poor response to treatment

    • Recurrent acute sinusitis

13.3 IMAGING STUDIES

A. X-RAY PARANASAL SINUSES (LIMITED ROLE)

  • Findings:

    • Air-fluid level

    • Sinus opacity

    • Mucosal thickening

  • Limitations:

    • Low sensitivity

    • Not recommended routinely

B. CT SCAN PARANASAL SINUSES (INVESTIGATION OF CHOICE WHEN INDICATED)

  • Indications:

    • Suspected complications

    • Severe or recurrent disease

    • Pre-surgical planning

  • Findings:

    • Mucosal thickening

    • Ostial blockage

    • Sinus opacification

    • Orbital or intracranial extension

Exam Pearl

CT scan is the investigation of choice in complicated acute sinusitis.

13.4 LABORATORY TESTS

  • CBC:

    • Leukocytosis in bacterial infection

  • Culture:

    • Rarely required

    • Reserved for resistant cases

14. DIFFERENTIAL DIAGNOSIS (VERY HIGH-YIELD TABLE)

Feature Acute Sinusitis Allergic Rhinitis Dental Pain Migraine
Nasal discharge Purulent Watery Absent Absent
Facial pain Present Rare Localized tooth Pulsatile
Fever Common Absent Absent Absent
Tenderness Present Absent Tooth Absent
Response to antibiotics Yes No No No

Examiner Trap

  • Facial pain without nasal discharge → not sinusitis

15. MANAGEMENT (CORE ENT EXAM SECTION)

15.1 PRINCIPLES OF MANAGEMENT

  • Restore sinus drainage

  • Reduce mucosal edema

  • Eradicate infection

  • Prevent complications

15.2 MEDICAL MANAGEMENT (FIRST-LINE)

15.2.1 ANTIBIOTIC THERAPY

  • Indicated when:

    • Symptoms persist > 7–10 days

    • Severe symptoms

    • High fever with purulence

Commonly Used Antibiotics

  • Amoxicillin ± clavulanate

  • Cefuroxime

  • Doxycycline (adults)

  • Macrolides (penicillin allergy)

Exam Line

Antibiotics are indicated in suspected bacterial acute sinusitis.

15.2.2 NASAL DECONGESTANTS

  • Reduce mucosal edema

  • Improve ostial drainage

  • Types:

    • Topical (xylometazoline)

    • Systemic (pseudoephedrine)

Caution

  • Topical decongestants not used > 5 days (risk of rhinitis medicamentosa)

15.2.3 ANALGESICS & ANTIPYRETICS

  • Paracetamol

  • NSAIDs

  • Relieve pain and fever

15.2.4 NASAL SALINE IRRIGATION

  • Clears secretions

  • Improves mucociliary clearance

  • Safe and effective adjunct

15.2.5 ANTIHISTAMINES

  • Used only if:

    • Associated allergic rhinitis present

16. SURGICAL MANAGEMENT (INDICATION-BASED)

16.1 INDICATIONS FOR SURGERY

  • Failure of medical therapy

  • Development of complications

  • Severe pain with pus retention

16.2 ANTRAL WASH (VERY HIGH-YIELD)

Indications

  • Acute maxillary sinusitis

  • Diagnostic and therapeutic

Procedure

  • Inferior meatus puncture

  • Saline irrigation

  • Removal of pus

Exam Line

Antral wash is both diagnostic and therapeutic in acute maxillary sinusitis.

16.3 FUNCTIONAL ENDOSCOPIC SINUS SURGERY (FESS)

  • Rare in acute cases

  • Indicated when:

    • Complications present

    • Anatomical obstruction

17. COMPLICATIONS (INTRODUCTION FOR EXAMS)

17.1 ORBITAL COMPLICATIONS

  • Preseptal cellulitis

  • Orbital cellulitis

  • Subperiosteal abscess

17.2 INTRACRANIAL COMPLICATIONS

  • Meningitis

  • Brain abscess

  • Cavernous sinus thrombosis

17.3 BONY COMPLICATIONS

  • Osteomyelitis of frontal bone (Pott’s puffy tumor)

(Each will be discussed in detail in PART 3)

18. OSCE / PRACTICAL STATIONS

18.1 SPOT DIAGNOSIS

  • Facial tenderness + purulent discharge
    Diagnosis: Acute sinusitis

18.2 MANAGEMENT STATION

  • Antibiotics

  • Decongestants

  • Analgesics

18.3 COUNSELLING STATION

  • Explain viral vs bacterial causes

  • Importance of completing antibiotics

  • Warning signs of complications

19. LONG CASE (UNIVERSITY STYLE)

History

  • Recent URTI

  • Facial pain

  • Purulent nasal discharge

Examination

  • Tenderness over sinus

  • Pus in middle meatus

Diagnosis

  • Acute sinusitis

Management

  • Medical therapy

  • Follow-up for complications

20. MCQs (EXAM-FOCUSED)

1. Most commonly involved sinus in acute sinusitis:
A. Frontal
B. Ethmoid
C. Maxillary
D. Sphenoid
Correct Answer: C

2. Key event in pathogenesis:
A. Bone erosion
B. Ostial obstruction
C. Allergy
D. Trauma
Correct Answer: B

21. VIVA QUESTIONS

  • Define acute sinusitis

  • Duration

  • Most common sinus involved

  • Investigation of choice in complications

  • Indication of antral wash

22. EXAMINER TRAPS

  • Treating viral sinusitis with antibiotics immediately

  • Missing orbital signs

  • Overuse of topical decongestants

  • Ignoring dental cause

23. CLINICAL PEARLS (EXAM GOLD)

  • Most cases are viral

  • Maxillary sinus most commonly involved

  • CT scan only for complications

  • Antral wash is therapeutic

  • Early treatment prevents serious complications

Written And Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change MBBS 4th Year (Fourth Year / Professional) Otorhinolaryngology (ENT) Free Material

24. RADIOLOGY–PATHOLOGY–CLINICAL CORRELATION (VERY HIGH-YIELD)

24.1 WHY THIS TRIAD IS TESTED

  • Acute sinusitis evolves from mucosal edema → ostial blockage → secretion retention → infection.

  • Imaging explains where drainage failed, pathology explains why pus formed, and clinical signs explain how pain localizes.

24.2 IMAGING FINDINGS EXPLAINED

CT PNS (WHEN INDICATED)

  • Mucosal thickening: edema from acute inflammation

  • Air–fluid level: acute exudation with partial ventilation

  • Sinus opacification: complete blockage

  • Osteomeatal complex obstruction: key driver of disease

  • Orbital fat stranding / lamina papyracea changes: early orbital spread

  • Frontal sinus posterior wall changes: risk of intracranial spread

Exam Line

CT delineates the osteomeatal complex and detects orbital or intracranial complications in acute sinusitis.

24.3 PATHOLOGICAL BASIS

  • Acute inflammatory infiltrate (neutrophils) → purulence

  • Vascular congestion → facial pain and tenderness

  • Ciliary dysfunction → impaired clearance

  • Pressure build-up → pain worsens on bending forward

24.4 CLINICAL CORRELATION BY SINUS

  • Maxillary: cheek pain, toothache (gravity-dependent drainage)

  • Frontal: morning headache (dependent overnight pooling)

  • Ethmoid: medial canthal pain; pediatric orbital risk

  • Sphenoid: deep retro-orbital/vertex headache; late diagnosis

25. COMPLICATIONS (COMPLETE, EXAM-SCORING SECTION)

25.1 ORBITAL COMPLICATIONS (MOST COMMON)

  • Preseptal cellulitis: eyelid edema, no visual loss

  • Orbital cellulitis: proptosis, painful eye movements, ↓ vision

  • Subperiosteal abscess: medial orbital swelling (ethmoid origin)

  • Orbital abscess: ophthalmoplegia, vision threat

Exam Line

Ethmoid sinusitis commonly leads to orbital complications.

25.2 INTRACRANIAL COMPLICATIONS

  • Meningitis

  • Epidural abscess

  • Subdural empyema

  • Brain abscess (frontal lobe commonly)

  • Cavernous sinus thrombosis (sphenoid/ethmoid)

Red Flags

  • Severe headache, altered sensorium, focal deficits, persistent fever

25.3 BONY COMPLICATIONS

  • Osteomyelitis of frontal bone (Pott’s puffy tumor)

    • Doughy forehead swelling

    • Requires urgent surgical drainage + IV antibiotics

26. MANAGEMENT OF COMPLICATIONS (STEP-WISE)

26.1 ORBITAL COMPLICATIONS

  • Admit patient

  • IV broad-spectrum antibiotics

  • Urgent ENT + Ophthalmology review

  • CT orbit + PNS

  • Surgical drainage if:

    • Vision compromised

    • Abscess present

    • No response to antibiotics

26.2 INTRACRANIAL COMPLICATIONS

  • ICU care

  • High-dose IV antibiotics (culture-guided)

  • Neurosurgical intervention when indicated

  • Address sinus source (FESS/antral wash)

27. PROGNOSIS

  • Excellent with early diagnosis and treatment

  • Good in most uncomplicated cases

  • Guarded if:

    • Orbital/intracranial complications

    • Delayed presentation

    • Immunocompromised state

28. PREVENTION (CLINICAL + PUBLIC HEALTH)

28.1 INDIVIDUAL LEVEL

  • Early treatment of URTI

  • Control allergic rhinitis

  • Smoking cessation

  • Adequate hydration

28.2 CLINICAL PRACTICE

  • Rational antibiotic use

  • Avoid prolonged topical decongestants

  • Correct anatomical obstruction when indicated

29. OSCE / PRACTICAL STATIONS (FULL SET)

29.1 SPOTTER

  • CT showing air–fluid level in maxillary sinus
    Diagnosis: Acute maxillary sinusitis

29.2 EXAMINATION STATION

  • Demonstrate sinus tenderness elicitation

  • Inspect middle meatus with endoscope

29.3 MANAGEMENT STATION

  • Outline medical management

  • Indications for antral wash

  • Warning signs requiring admission

30. LONG CASE (UNIVERSITY FORMAT)

History

  • Recent URTI, facial pain, purulent discharge, fever

Examination

  • Maxillary tenderness, pus in middle meatus

Investigations

  • Clinical diagnosis

  • CT if complications suspected

Diagnosis

  • Acute bacterial rhinosinusitis

Management

  • Antibiotics + decongestants + analgesia

  • Antral wash if indicated

  • Close follow-up

31. MCQs (FINAL SET)

1. Key event in acute sinusitis pathogenesis:
A. Bone erosion
B. Allergy
C. Ostial obstruction
D. Trauma
Correct Answer: C

2. Most common sinus involved:
A. Frontal
B. Ethmoid
C. Maxillary
D. Sphenoid
Correct Answer: C

3. Most common orbital complication source:
A. Maxillary
B. Frontal
C. Ethmoid
D. Sphenoid
Correct Answer: C

32. VIVA QUESTIONS (RAPID-FIRE)

  • Define acute sinusitis

  • Duration criteria

  • Most common sinus involved

  • Key pathogenesis step

  • Indication of CT

  • Indication of antral wash

  • Name orbital complications

33. EXAMINER TRAPS (AVOID THESE)

  • Immediate antibiotics for viral disease

  • Missing orbital signs in children

  • Overusing topical decongestants

  • Ignoring dental source in maxillary sinusitis

34. CLINICAL PEARLS (EXAM GOLD)

  • Most cases are viral; antibiotics when bacterial suspected

  • Osteomeatal complex obstruction is central

  • CT only for complications or refractory cases

  • Ethmoid sinusitis → orbital risk

  • Early treatment prevents life-threatening spread

Written And Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change MBBS 4th Year (Fourth Year / Professional) Otorhinolaryngology (ENT) Free Material

Hunain Zia

Hunain Zia has previously achieved considerable success in the high-school educational stream, gaining a massive 154 Total A Grades and 7 Major Distinctions, a process in which he broke/ set 11 different world records, including the most A grades ever achieved, most subjects ever appeared in, most distinctions, gaining distinctions across two separate boards (Pearson Edexcel and CAIE) within the same year/ ever, and even 19 hours of constant examination. All records stand intact today. Hunain pursued his Honors Accounting Degree from the prestigious Bentley University, and then completed an LLB (in Honors) from University of London. Currently, he manages multiple social and commercial projects, has founded digital streams and works tirelessly in the education sector.

Educate A Change focuses on truly bringing change in the educational sector worldwide. All our courses are designed to ensure success, and provide complete preparation without requiring any other external material. Therefore, it takes away the expense of academies, books, past paper compilations and other miscellaneous items. Instead, by just the courses we offer, the student can prepare fully for the best grades in their CAIEs, Edexcel and other high-school exams. The earnings from our course-sales are invested in social projects and growing the free educational activities of Educate A Change.