Clinical Pearls & Morning Reports
Increased intracranial pressure that does not have a defined cause, which is known as idiopathic intracranial hypertension or pseudotumor cerebri, is a disorder that predominantly affects obese women of childbearing age. Read the latest Case Records of the Massachusetts General Hospital here.
Q: What are the signs that distinguish true optic-disk edema from pseudopapilledema?
A: The 10 signs of true optic-disk edema can be assessed on a fundus examination. The 5 mechanical signs are loss of the physiological cup, elevation of the disk, blurring of the disk margins, edema of the nerve fiber layer, and folds of the retina or choroid. The 5 vascular signs are hyperemia of the disk, venous dilatation and tortuosity, peripapillary hemorrhages, infarct of the nerve fiber layer (cotton wool spots), and exudates.
Q: What are transient visual obscurations?
A: Episodes of painless vision loss that last only seconds and are aggravated by changes in position, such as bending over, are referred to as transient visual obscurations. The brevity of transient visual obscurations distinguishes them from amaurosis fugax and other considerations, such as migraine. Transient visual obscurations occur in the context of optic-disk edema (either papilledema or papillitis) and are thought to result from changes in position that affect perfusion to the swollen optic-nerve heads. They are a common symptom in patients with papilledema.
A: Papilledema is optic-disk edema that is caused by increased intracranial pressure, whereas papillitis is optic-disk edema that is caused by an optic neuropathy or damage to the optic nerve. The characteristic features of papillitis due to an acquired optic neuropathy include decreased visual acuity, loss or impairment of color vision (dyschromatopsia), a relative afferent pupillary defect, and visual-field defects. In affected patients, the optic-disk swelling is usually unilateral, with the major exception being swelling due to hypertensive crisis. In contrast, patients with papilledema initially have no vision symptoms and usually have normal visual acuity, color vision, and pupillary responses, with no relative afferent pupillary defect. Visual-field testing commonly reveals enlarged blind spots in both eyes, and as the disease progresses, the peripheral nasal fields become affected. Central visual-field defects develop late in the course of papilledema, and these are usually accompanied by decreased visual acuity and dyschromatopsia. A relative afferent pupillary defect is present only in highly asymmetric cases, in which the optic-disk edema and subsequent vision loss are worse in one eye.
A: Headaches caused by increased intracranial pressure can be similar to migraines, which are unilateral throbbing or tension headaches that are associated with photophobia, phonophobia, nausea, and vomiting and are often preceded by a visual aura with a scintillating or zigzag pattern that lasts for 20 to 60 minutes. Unlike migraines, headaches caused by increased intracranial pressure may be accompanied by tinnitus characterized by a whooshing noise in one or both ears that occurs in synchronization with the pulse. The headache and tinnitus are typically worse when the patient is lying flat and better when the patient is sitting or standing. Headaches caused by increased intracranial pressure are often accompanied by transient visual obscurations. These headaches are also occasionally associated with binocular horizontal diplopia due to a sixth-nerve palsy. Headaches caused by increased intracranial pressure do not necessarily occur in one specific area. Some patients with increased intracranial pressure have pain behind the eyes that may be exacerbated by eye movement, whereas others report pain that is located at the back of the head or begins on one side.