E4810. From Scans to Solutions: MRI’s Role in Diagnosing Spontaneous Intracranial Hypotension (SIH)
  1. Jordan Hughes; Yale New Haven Bridgeport Hospital
  2. Anisa Chowdhary; Yale New Haven Bridgeport Hospital
  3. Namita Bhagat; Yale New Haven Bridgeport Hospital
  4. Anish Neupane; Yale New Haven Bridgeport Hospital
  5. Gaurav Cheraya; Yale New Haven Bridgeport Hospital
  6. Ismail Yardimcioglu; Yale New Haven Bridgeport Hospital
  7. Ajay Malhotra; Yale New Haven Health
Spontaneous intracranial hypotension (SIH) is a condition that results from leakage of CSF from the spine, which typically presents with debilitating orthostatic headache but can be associated with a wide range of other symptoms. Other common clinical features include fever, nausea, vomiting, and tinnitus. Imaging plays a central role in the initial diagnosis of SIH and in its subsequent investigation and management.

Educational Goals / Teaching Points
Knowledge of the typical clinical symptoms of IH and careful MRI assessment may lead to a correct diagnosis, thus obviating the need for further, especially invasive, procedures. Numerous cranial MRI signs of SIH have been described using different MRI sequences on 1.5 and 3-T scanners. There is neither a definite MRI sign, nor a definite MRI protocol, and it is rather the combination of MRI signs that allow physicians to diagnose SIH with a high grade of certainty. Dobrocky et al. proposed a score for the most accurate MRI signs in 2019, which was later termed the Bern score. Major criteria: engorgement of venous sinuses; pachymeningeal enhancement; suprasellar cistern ? = ? 4 mm. Minor criteria: subdural fluid collection; prepontine cistern ? = ? 5 mm; mamillopontine distance ? = ? 6.5 mm.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Diagnostic criteria include a CSF pressure ? < ? 60 mm H2O and/or evidence of a CSF leak on imaging. As lumbar puncture is invasive and only one-third of SIH patients has a CSF opening pressure ? < ? 60 mm H2O, MRI of the head and the spine is mandatory. Apart from diffuse intracranial pachymeningeal enhancement, MRI may show: 1) sagging of the brain; 2) pituitary enlargement; 3) subdural fluid collections, less commonly hematomas; 4) posterior lobe pituitary hematomas; 5) diffuse dural enhancement of the spinal canal; 6) spinal epidural fluid collection; 7) distension of the spinal epidural venous plexus; and/or 8) abnormal T2 signal intensity around the root sleeves.

SIH is caused by various types of defects in the spinal dura and subsequent CSF extravasation. Many radiologic and clinical findings may mimic these classic findings, and, conversely, secondary changes from SIH can give rise to symptoms that imitate other conditions. Because SIH is a curable condition, it is important for physicians to recognize its nonclassic presentations and be familiar with the differential diagnoses of its radiologic and clinical findings.