Idiopathic Intracranial Hypertension Without Papilledema: A Case Emphasizing the Diagnostic Value of Optic Nerve Sheath Ultrasound.

We report the case of a 45-year-old woman with obesity who presented with some features of idiopathic intracranial hypertension (IIH), including postural headache and pulsatile tinnitus, but notably without papilledema. Initial investigations, including optical coherence tomography (OCT) of the optic nerve and computed tomography (CT) of the head, were unremarkable, resulting in a delay in diagnosis. Due to persistent symptoms, optic nerve sheath diameter (ONSD) assessment via ultrasound was performed, revealing bilateral dilation. Subsequent magnetic resonance imaging (MRI) identified an empty sella and distension of the optic nerve sheaths. A lumbar puncture confirmed an elevated opening pressure of 30 cm H₂O, establishing the diagnosis of IIH. This case illustrates the diagnostic challenges of IIH in the absence of papilledema and emphasizes the emerging utility of optic nerve sheath ultrasound as a non-invasive tool to aid in the early detection of raised intracranial pressure.