Raised intracranial pressure (ICP) is a common and life threatening condition especially in patients with traumatic brain injury.There are many methods for monitoring the increased (ICP) either invasive or non- invasive ,but the gold standard is invasive method. Optic nerve sheath ultrasonography provides a very promising bedside tool for detection of increased ICP. This study will monitor the dynamic changes of intracranial pressure by optic nerve sheath diameter (ONSD) in response to mannitol osmotherapy

Traumatic brain injury is the main cause of increased intracranial pressure (ICP) in the intensive care .

There are multiple methods for monitoring the raised ICP either invasive or non-invasive.The gold standard is the invasive devices because it is more accurate and reliable .However ,it requires a surgical intervention which has many hazards such as (infection ,hemorrhage,malfunction ).

Optic nerve sheath ultrasonography is a promising bedside tool for detection of increased ICP. The optic nerve is surrounded by cerebro-spinal fluid ,thus if the circulation of cerebro-spinal fluid not blocked ,an increase in ICP will be transmitted through the subarachnoid space around the optic nerve within the nerve sheath especially the retro-bulbar segment.

The study will be conducted to monitor the dynamic changes of intracranial pressure by optic nerve sheath diameter (ONSD) in response to mannitol osmotherapy as a primary outcome and secondary to evaluate the efficacy of ONSD in assessing the severity of the disease

Inclusion Criteria:

• Patients with traumatic brain injury

Exclusion Criteria:

• Patients with history of optic neuritis
• past history of eye trauma
• patient with optic nerve trauma
• patient with history of arachnoid cyst of the optic nerve
• high myopic patients
• patients with cavernous sius mass

No masking