Absence of papilledema in large intracranial tumours.

Papilledema refers to optic disc edema occurring secondary to raised intracranial pressure. In patients with intracranial tumours, tumour size might be the expected predictor of whether or not papilledema will develop, however, this is not the case in clinical practice. We report a series of 5 patients with large intracranial tumours and no evidence of papilledema and discuss the potential factors which may contribute to the lack of optic disc edema in these cases. Development of papilledema depends on both the presence of elevated intracranial pressure and transmission of elevated pressure to the subarachnoid space within the optic nerve sheath and to the optic nerve itself. We discuss how intracranial tumours may influence the physiology of the surrounding tissues, cerebrospinal fluid dynamics and cerebral venous outflow and how individual anatomic variations, particularly within the optic nerve sheath and optic canal, likely play a role in development of papilledema.