Management of optic neuritis and multiple sclerosis

Activity of attention related structures in multiple sclerosis patients

AIMS

It was investigated whether the cortical activity during tasks requiring focused or divided attention is reduced in multiple sclerosis patients with prominent deficits (MS(+D)) and increased in patients without impairment (MS(-D)) in these specific attention functions.

METHODS

Six MS(+D) patients with attention deficits, six unimpaired MS(-D) patients, and age-, gender-, and education-matched healthy control subjects were examined with functional magnetic resonance imaging (fMRI). The experimental paradigm consisted of visual tasks requiring focused or divided attention.

RESULTS

Performance accuracy and reaction times were impaired in MS(+D) patients. This subgroup showed reduced activation within superior and inferior frontal gyrus during focused attention. Under conditions of divided attention decreased activity was found within middle and inferior frontal gyrus, inferior parietal structures, and occipital areas. No compensatory activity was observed. MS(-D) patients did neither differ in behavioral data nor in cortical activity in attention related structures from control subjects.

CONCLUSIONS

The study found evidence for the neural correlate of attentional deficits in MS patients. In patients with specific attention deficits, reduced cortical activity in prefrontal and parietal areas, which are associated with attention and executive control, reflects the patients' reduced performance on a behavioral level. Our findings also suggest impaired top-down attentional control on sensory structures in these patients. In patients without verifiable attention deficits a normal functioning of structures relevant for executive attention was observed. Compensatory activity in these structures as a marker of reorganization in less pronounced stages of the disease was not found.

Optic Neuritis: The Role of Disease-modifying Therapy in This Clinically Isolated Syndrome

Optic neuritis (ON) is an important clinical entity, which may herald the diagnosis of multiple sclerosis (MS). Patients with acute monosymptomatic ON generally have a good visual prognosis, and the speed of recovery may be hastened with intravenous methylprednisolone. The question of whether disease-modifying therapy should be initiated after ON as a clinically isolated syndrome is a controversial topic, and factors specific to the patient should be taken into consideration before weighing in favor or against this therapeutic option. A significant proportion of patients with ON will go on to develop MS, and early initiation of therapy may delay this diagnosis. In addition, disease-modifying therapies also may reduce the disabling effects of MS among patients, but this is unknown. There are approved therapies currently available for patients with ON and an abnormal baseline cranial MRI scan, which predict a greater risk of future MS. Patients with a higher baseline MRI burden of disease, multifocal symptomatology (including sensory complaints) at onset, a high relapse rate, and a rapid accumulation of disability within the first few years of diagnosis may benefit from early and aggressive therapy with the disease-modifying drugs that are currently available. ON patients with few or no lesions on their baseline MRI scans and those with low rates of clinical relapse may be selected for careful clinical follow-up and monitored for signs of disease activity before the role of disease-modifying therapy is determined. ON patients with no light perception vision at presentation, marked optic disc swelling, and other atypical clinical features (including peripapillary hemorrhages or retinal exudates) may have a reduced risk of future MS, and for these patients, disease-modifying therapy may be deferred until it is deemed necessary by the patient and the treating physician.