MRI Morphology and Cerebral Venous Drainage in Idiopathic Intracranial Hypertension (IIH)

Abstract

 

Purpose:

 

IIH is a significant cause of vision loss in young obese women. We aim to understand the pathophysiology of IIH by comparing MRI morphology and cerebral venous drainage patterns in patients with untreated IIH and similar age, gender and BMI controls.

 

Methods:

 

11 females with untreated IIH (age 28.6±8.9 years, BMI 34.2±5.1 kg/m2) and 8 healthy females (age 31.8±9.9 years, BMI 36.4±5.8 kg/m2) underwent morphologic, venographic and dynamic MR imaging as well as a clinical eye exam. Velocity encoded scans were used to obtain cerebral blood flow measurements. The two study groups were studied based on differences in pituitary gland area, total cerebral blood flow and venous outflow, papilledema grade and visual fields.

 

Results:

 

IIH patients presented with mildly affected visual parameters with papilledema. However, they had significantly smaller pituitary area normalized to the sella turcica area (p<0.00001) compared to controls, indicating ‘empty sella syndrome’. Both groups showed similar total cerebral blood flow (TCBF). The total internal jugular flow (TIJF) (primary channels) was significantly lower among IIH patients (p=0.032) with greater flow through secondary channels. This difference was further enhanced by normalizing TIJF to TCBF (p=0.004). Moreover, bilateral transverse sinus flow gaps were observed on MR venography in 9 out of 11 patients and in none of the controls, except 2 subjects with a unilateral transverse sinus flow gap (Figure 1).

 

Conclusions:

 

Empty sella syndrome, increased flow through secondary venous channels and bilateral flow gaps in the transverse sinuses are important observations that help improve the understanding of IIH.  

 

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • visual impairment: neuro-ophthalmological disease • neuro-ophthalmology: diagnosis