Table 1:

Distinguishing features of alternative diagnoses that occasionally mimic spontaneous intracranial hypotension

	Distinguishing Features	SIH
Radiologic mimickers
Chiari type I malformation	Cerebellar tonsils inferiorly pointed Midbrain descent absent	Normal cerebellar tonsil shape Midbrain descent present
Subdural fluid collections	Usually unilateral	Usually bilateral Brain sag and focal dural enhancement
Conditions with dural thickening (IgG4-related disease, neurosarcoidosis, tuberculosis, autoimmune diseases, infectious diseases)	Focal or diffuse May have leptomeningeal involvement, skull base prominence, hypertrophic pachymeningitis Usually systemic symptoms and involvement of other organs	Diffuse, non-nodular dural thickening and enhancement
Clinical mimickers
POTS	Increased heart rate with minimal change in blood pressure on standing from a seated or supine position	Stable heart rate with postural changes
Orthostatic hypotension	Autonomic failure, medication effect, hypovolemia Fall in systolic (20 mm Hg) and/or diastolic (10 mm Hg) blood pressure on standing from a seated or supine position	Stable blood pressure with postural changes
Cervicogenic headache	Headache with neck pain that worsens with cervical motion, relieved with medication	Pain is typically centered in the head and not worsened by cervical motion or improved with medications
Vestibular migraine	Vertigo, unilateral headache, nystagmus, presence of aura, history of migraine	Hearing changes and tinnitus more than vertigo or nystagmus