Rare Case of Unilateral Disc Oedema Secondary to Idiopathic Intracranial Hypertension

Majority of idiopathic intracranial hypertension (IIH) cases present with bilateral papilloedema. Unilateral papilloedema is a rare condition in IIH. This is a report of one such unusual case. Papilloedema is clinically defined as swelling of the optic nerve head secondary to raised intracranial pressure.1 Disc oedema is a non-specific term that includes papilloedema but also refers to a disc swollen from other causes. Classically, presence of papilloedema is most commonly due to an intracranial space occupying lesion leading to raised intracranial pressure; however, it may be caused due to other aetiologies such as hydrocephalus, shunt failures, idiopathic intracranial hypertension and drugs.2 Idiopathic intracranial hypertension, also known as pseudotumour cerebri, is a disorder characterised by increased intracranial pressure of unclear pathogenesis in the absence of other structural and obstructive lesions. This is a case of acute established unilateral disc oedema secondary to idiopathic intracranial hypertension.

Idiopathic intracranial hypertension

Idiopathic intracranial hypertension (IIH) (also called pseudotumour cerebri and, previously, benign intracranial hypertension) is a syndrome of raised intracranial pressure in the absence of an intracranial mass lesion, enlargement of the cerebral ventricles, or venous sinus thrombosis. IIH affects predominantly obese women of childbearing age (>90%). The condition has considerable morbidity from permanent visual loss (up to 25% of cases) and chronic disabling headaches, which result in poor quality of life. Patients presenting acutely with papilloedema must be evaluated urgently for secondary causes of raised intracranial pressure (e.g. space occupying lesion and venous thrombosis). After this, the priority is to assess accurately the threat to vision. In most patients, the condition becomes chronic and the disease burden is mostly from chronic headaches, which need active management, alongside visual monitoring. This chapter does not cover paediatric IIH.

Coupling of CSF and sagittal sinus pressure in adult patients with pseudotumour cerebri

Objective Pseudotumour cerebri syndrome (PTCS including idiopathic intracranial hypertension) is characterised by the symptoms and signs of raised cerebrospinal fluid pressure (CSFp) in the absence of ventricular dilatation or an intracranial mass lesion. Its aetiology is unknown in the majority of cases but there is much evidence for impaired CSF absorption. Traditionally, sagittal sinus pressure has been considered to be independent of CSF pressure in adults. However, the discovery of stenoses of intracranial venous sinuses and introduction of venous sinus stenting has highlighted the importance of the venous drainage in PTCS. In this study, we have explored the relationship between CSFp and SSp before and during a CSF infusion test and during CSF drainage. Materials and methods Ten patients (9 females:1 male) with PTCS underwent infusion studies in parallel with direct retrograde cerebral venography. Both SSp and CSFp were recorded at a baseline and during CSFp elevation in a course of a CSF infusion test. The drainage of CSF after the CSF infusion was performed in 7 patients. In 5 cases, jugular venous pressure was also measured. Results CSFp and SSp including their amplitudes correlated significantly and strongly both at baseline (R = 0.96; p = 0.001) and during infusion (R = 0.92; p = 0.0026). During drainage, this correlation was maintained until SSp reached a stable value, whereas CSFp continued to decrease. Conclusions In this series of ten patients with PTCS, CSFp and SSp were coupled, both at baseline and during infusion. The implications of such coupling for the calculation of CSF outflow resistance are discussed.