Describe cerebrospinal fluid rhinorrhoea.

Nature and Diagnosis

• CSF rhinorrhoea is leakage of cerebrospinal fluid from the nose, through a defect in the dura and the bone of the anterior skull base.
• Its importance lies almost entirely in the risk of meningitis, which persists for as long as the leak does.
• Classification and causes:
• Traumatic accounts for the great majority — closed head injury with a fracture of the cribriform plate, the fovea ethmoidalis, the frontal sinus or the sphenoid
• Iatrogenic — after endoscopic sinus surgery (classically at the medial ethmoid roof beside the cribriform plate, the thinnest point), skull base or pituitary surgery
• Spontaneous — characteristically in obese, middle-aged women with raised intracranial pressure and a thinned skull base.
• Also — tumours eroding the skull base, congenital defects and encephalocele, and previous radiotherapy
• Clinical features — unilateral, clear, watery discharge.
• The patient may describe a salty or metallic taste as fluid runs into the pharynx; and there may be postural headache, anosmia (from associated cribriform injury), and a history of recurrent meningitis
• Recurrent meningitis always demands A search for A CSF fistula, and is the presentation that must never be missed
• The reservoir sign — fluid accumulating while recumbent and gushing out on sitting up or bending forward
• Diagnosis:

Management

• Conservative management first for a traumatic leak, since the majority close spontaneously within 7 to 10 days
• Measures — bed rest with the head elevated 30 degrees; avoidance of nose-blowing, straining, coughing and sneezing (sneeze with the mouth open); stool softeners; and avoidance of nasal packing and instrumentation
• A lumbar drain where the leak persists, reducing the pressure across the defect
• Prophylactic antibiotics are not recommended in current guidance — they do not reduce the incidence of meningitis and select resistant organisms. This runs against older teaching and is worth stating clearly
• Vaccinate against pneumococcus (and consider meningococcal and Hib) in a patient with a persistent or recurrent leak, since Streptococcus pneumoniae is the usual organism
• Surgical repair is indicated where the leak persists beyond 10 days to 2 weeks, recurs, follows meningitis, is spontaneous (which rarely closes alone), is associated with an encephalocele, a large defect or a tumour, or is delayed in onset
• The endoscopic endonasal approach is now the standard, with success rates above 90%, and has largely replaced the intracranial (frontal craniotomy) approach.
• Principles of repair — identify the defect precisely; freshen the margins and remove mucosa from the edges.