CSF Rhinorrhoea

Definition: Leakage of CSF into the nose. It may be clear fluid or mixed with blood (in acute head injuries).

Physiology of CSF

Function: Forms a fluid jacket around brain/cord acting as a buffer against sudden jerks.

Mechanism: Secreted by Choroid Plexus (Lat/3rd/4th ventricles) → Absorbed by Arachnoid Villi (One-way valve) → Dural Venous Sinuses.

Aetiology & Sites of Leak

1. Aetiology

• Trauma (Most Common):
  • Accidental or Surgical (FESS, Hypophysectomy, Nasal Polypectomy, Skull base surgery).
  • Note: In FESS, leak may be immediate or delayed in onset.
• Inflammation: Mucoceles, Sinonasal polyposis, Fungal infections, Osteomyelitis (erode bone/dura).
• Neoplasms: Benign/Malignant invading skull base.
• Congenital: Meningocele, Meningoencephalocele, Gliomas.
• Idiopathic: Spontaneous leak.

2. Sites of Leakage

Origin	Pathway to Nose
Anterior Cranial Fossa	Cribriform plate, Roof of Ethmoid, Frontal Sinus.
Middle Cranial Fossa	Sphenoid Sinus.
Temporal Bone	Fracture → Middle Ear → Eustachian Tube → Nose (CSF Otorhinorrhoea).

Diagnosis

Clinical Features

• History of clear watery discharge on bending/straining.
• Reservoir Sign: Patient wakes up → bends head → pool of fluid (collected in Sphenoid) gushes out.
• Handkerchief does not stiffen (unlike mucus).
• Otoscopy: May show fluid in middle ear (Otorhinorrhoea).

The Double Target Sign

Seen in bloody traumatic leaks collected on filter paper.

Differentiation: CSF vs. Nasal Secretion

Feature	CSF	Nasal Secretion (Rhinitis)
History	Trauma/Surgery/Tumour	Sneezing, Itching, Lacrimation
Flow	Gushes on bending; Cannot be sniffed back.	Continuous; Can be sniffed back.
Character	Thin, Watery, Clear	Slimy (Mucus)
Taste	Sweet	Salty
Sugar	> 30 mg/dL	< 10 mg/dL
Beta-2 Transferrin	ALWAYS PRESENT (Specific)	Absent

Laboratory & Imaging

1. Lab Tests

• Beta-2 Transferrin: Gold Standard. Highly specific/sensitive. Found only in CSF, Perilymph, Aqueous humour.
• Beta Trace Protein: Secreted by meninges/choroid plexus. Specific (Used in Europe).
• Note: Glucose testing (oxidase peroxidase) is unreliable and no longer used.

2. Localization of Defect

• HRCT: Coronal/Axial cuts (1-2mm). Best for bony defects (Frontal/Sphenoid).
• MRI (T2 Weighted): Best for active leaks, encephaloceles. Non-invasive.
• Intrathecal Fluorescein Study (Invasive):
  • 0.25-0.5 mL of 5% Fluorescein + 10 mL CSF injected intrathecally.
  • Patient placed 10° head down.
  • Endoscopy: Dye appears Fluorescent Green under blue filter.
  • Sites to check:
    • Olfactory Cleft (Cribriform plate)
    • Middle Meatus (Frontal/Ethmoid)
    • Sphenoethmoidal Recess (Sphenoid)
    • Torus Tubarius (Temporal bone/Eustachian tube)
• Other: Intrathecal radioactive substances (Abandoned). CT Cisternogram (requires iohexol, not favoured).

Treatment

1. Conservative (Early/Traumatic Cases)

• Bed rest with head elevated.
• Stool softeners.
• Avoid: Nose blowing, sneezing, straining.
• Prophylactic Antibiotics (prevent Meningitis).
• Acetazolamide (decreases CSF production).
• Lumbar drain (if pressure is high).

2. Surgical Repair

A. Neurosurgical: Intracranial approach.

B. Extradural Approaches:

• External Ethmoidectomy (Cribriform/Ethmoid leaks).
• Trans-septal Sphenoidal approach (Sphenoid leaks).
• Osteoplastic Flap + Fat Obliteration (Frontal sinus leaks).

C. Transnasal Endoscopic Approach (Success ~90%):

*If defect > 2cm: Use Cartilage (Septum/Concha) or Fat plug.