ONSD Trajectory in Rebound ICH

Traumatic brain injury (TBI) is a major cause of morbidity and mortality worldwide. Cerebral edema and elevated intracranial pressure (ICP) are common secondary complications that require prompt management to prevent further neurological injury. Osmotherapy with hypertonic saline or mannitol is routinely used to reduce ICP; however, withdrawal or weaning of osmotherapy may be associated with rebound intracranial hypertension, which can worsen neurological outcomes if not recognized early.

Optic nerve sheath diameter (ONSD), measured by bedside ocular ultrasonography, is a non-invasive surrogate marker of raised intracranial pressure. Although ONSD has been shown to correlate with ICP in several clinical settings, the predictive value of serial ONSD measurements during osmotherapy weaning for identifying rebound intracranial hypertension has not been adequately investigated.

Inclusion criteria

• Adults (≥18 years) with blunt traumatic brain injury admission GCS ≤12
• (or GCS 13-15 with CT signs of elevated ICP including midline shift ≥5 mm, effaced cisterns, or significant cerebral edema)
• clinical decision to initiate 20% mannitol osmotherapy

Exclusion criteria

• Ocular conditions precluding ONSD measurement (glaucoma, prior ocular surgery,
• globe or optic nerve trauma,
• periorbital edema, orbital masses, optic nerve sheath cysts);
• planned decompressive surgery or evacuation of mass lesion within 48 hours; limitation of life-sustaining therapy; pregnancy; contraindications to mannitol (baseline sodium >155 mEq/L, osmolality >320 mOsm/kg, eGFR <30 mL/min); penetrating TBI; or concurrent spinal cord injury with shock.