Review Question - QID 102731

The patient in this vignette with decreased visual acuity and pain with eye movement in the right eye most likely has optic neuritis. The most common cause of optic neuritis, especially in young female patients, is multiple sclerosis.

Multiple sclerosis (MS) is an autoimmune demyelinating condition involving multiple neurologic deficits separated in space and time. The exact etiology of the disease is unknown, although it is believed to result from autoimmune destruction of myelin in the central nervous system. It most commonly presents in the third to fourth decade of life, and women are affected more commonly than men. Classic findings on MRI of the brain and spinal cord include multiple focal areas of demyelination throughout the brain and spinal cord and asymmetric periventricular plaques, commonly referred to as “Dawson’s fingers”. CSF may also be studied, but is more invasive and is not usually required to make the diagnosis. Oligoclonal IgG bands on CSF is a characteristic finding of multiple sclerosis.

Dobson et. al review the clinical manifestations, diagnosis and management of multiple sclerosis. They note the use of MRI of the brain and spinal cord as a central part of diagnosis for most patients. They further discuss options for management in patients with MS.

Illustration A displays an MRI of the brain with findings characteristic of multiple sclerosis. Note the numerous enhancing lesions bilaterally.

Incorrect Answers:
Answer 1: Cerebral angiography can be used to diagnose vascular disorders of the brain, such as aneurysm. While cerebral aneurysms may compress nearby structures leading to visual loss, this patient’s age and history is much more suggestive of MS. Cerebral angiography is not used to diagnose MS.

Answer 2: CT scan of the brain would not be appropriate. This patient’s presentation is strongly suggestive of MS. MRI is preferred over CT for the diagnosis of MS due to its superior ability to detect demyelinating lesions.

Answer 3: Fundoscopic exam may reveal retinal detachment, which can cause monocular visual loss. However, this patient’s associated painful eye movements and history of extremity weakness suggests MS. Fundoscopic exam is not useful in the diagnosis of MS.

Answer 5: Peripheral blood antibody titers are unlikely to be useful in this patient with likely MS. While MS is thought to be due to an antibody mediated autoimmune process, these antibodies are located in the cerebrospinal fluid, and would not be detected in peripheral blood.

Bullet Summary:
In patients with symptoms suggestive of likely multiple sclerosis, MRI of the brain and spinal cord is the most appropriate first step in diagnosis.