Optic neuritis--a sign of multiple sclerosis or other diseases of the central nervous system

Global visual field involvement in acute unilateral optic neuritis

PURPOSE

To quantify automated visual field defects seen at entry in the Optic Neuritis Treatment Trial (ONTT) to determine whether particular areas of the field are preferentially affected and to determine the extent of visual field involvement in patients having "localized" field defects.

METHODS

Review of Humphrey 30-2 Visual Field (Allergan-Humphrey, Inc, San Leandro, CA) data from the involved and fellow eyes of 440 patients who were enrolled in the ONTT. Field defects were evaluated by comparing the involved eye to the fellow eye.

RESULTS

Patients with diffuse visual field defects had a relatively equal diminution of visual threshold throughout the tested 30-2 field. Patients with localized central and cecocentral scotomas had their greatest depression of threshold centrally; however, even those patients with mild defects (mean defect, <6 dB) had diminution of visual threshold throughout the entire tested 30-degree field. Patients with moderate (mean defect, 6 to 20 dB) and severe (mean defect, >20 dB) central and cecocentral defects had even greater peripheral depression. Patients with altitudinal or quadrant defects had involvement of the "unaffected" field that also varied with the mean defect. The overall average depression of visual threshold for all patients averaged 36%+/-4% and was relatively uniform throughout the tested field.

CONCLUSIONS

Optic neuritis affects the entire central 30-2 field, even in patients who appear to have localized depression of visual threshold. Optic neuritis does not appear to have a predilection for any particular area of the visual field.

Optic nerve: a concise review of the anatomy, pathophysiology and principal acquired disorders

The Authors review the acquired diseases of the optic nerve (o.n.) through a selection of a few main nosological categories elaborated according to recent literature and neuro-imaging developments. The proposed selection does not coincide with a classification as it includes different topics, some listed according to their aetiology, others on the clinical presentation. However, from a practical point of view, a simplified nosology should help in dealing with the complex variety of o.n. diseases and in tackling the difficulties of their differential diagnosis.

A reassessment of the risk of multiple sclerosis developing in patients with optic neuritis after extended follow-up

One hundred and one of 146 patients presenting with isolated idiopathic optic neuritis, previously reviewed in 1978, were reassessed clinically, and retyped for HLA antigens and Factor B alleles, after a mean follow-up of 11.6 years. Fifty eight patients (57%) had developed multiple sclerosis at the time of reassessment in the present study, of whom 51 (88%) had clinically definite disease. This compared with 40% of the original group, in 1978, of whom 62% then had clinically definite multiple sclerosis. When the life-table method of analysis was used, the probability of developing multiple sclerosis was 75%, 15 years after the initial episode of optic neuritis. The frequencies of HLA-DR2 and the recently defined D-region antigen, DQw1, were significantly increased in patients with isolated optic neuritis and those who subsequently developed multiple sclerosis compared with normal controls, but neither allele appears to influence progression from optic neuritis to multiple sclerosis. Patients with optic neuritis who were HLA-DR3 positive had an increased risk for the development of multiple sclerosis (RR = 2.8) and this risk was further enhanced when DR3 occurred in combination with DR2 (RR = 6.7). The overall increased risk of developing multiple sclerosis for patients with this combination was 26 times that for the normal population. When the patients' original tissue-typing was considered BT 101 no longer influenced conversion of optic neuritis to multiple sclerosis. This may partly be explained by improved methods of tissue-typing, since not all BT 101 patients were subsequently found to be positive for HLA-DR2 or HLA-DQw1 and vice versa and by extended follow-up as multiple sclerosis conversion in HLA-DR2 negative individuals increased with time. All 101 patients were typed for Factor B alleles. No significant differences in frequencies were found between individuals with isolated optic neuritis or those who progressed to multiple sclerosis compared with the control population. Recurrent episodes of optic neuritis were associated with an increased risk for the development of multiple sclerosis in this study.

Acute optic neuritis: a prospective study of risk factors for multiple sclerosis

Eighty two patients with isolated optic neuritis were studied prospectively to determine the frequency with which multiple sclerosis developed and the factors which increased its risk. Patients were followed for 6 to 264 months (mean, 57 months). Twenty six patients (32%) developed clinically definite or probable multiple sclerosis during the period of follow-up. Actuarial analysis predicted that 42% would develop multiple sclerosis by 7 years. Of those patients who developed multiple sclerosis, 92% had symptoms within 4 years of the first attack of optic neuritis. The highest incidence of multiple sclerosis occurred in the 21-40 year age group. There was an increased risk of MS in patients with HLA-DR2 and HLA-B7 tissue types. The frequency of HLA-DR4 was increased in patients with optic neuritis alone compared to controls and to patients with multiple sclerosis, but further studies are required to confirm this finding.

Presenting signs and symptoms in multiple sclerosis

The disability outcome related to the presenting signs and symptoms was studied retrospectively in 193 patients with definite multiple sclerosis (MS). Patients whose first sign was motor weakness were found to be more severely disabled, at all stages throughout the course of the disease, than patients with other presenting signs or symptoms. Patients whose disease manifested initially with sensory disturbances or paraesthesiae proved to be less seriously disabled than other patients at all stages of the disease. A similar tendency was found in patients presenting with optic neuritis (ON) for the first 20 years of the disease; after that, their disability was comparable to that of patients with other presenting complaints. The difference during the first 20 years of the disease is mainly due to the asymptomatic period after initial manifestation of optic neuritis.

The blink reflex and somatosensory evoked potential in optic neuritis in south India

Optic Neuritis (ON) proceeds to multiple sclerosis (MS) in a considerable number of patients. The blink reflex (BR) and somatosensory evoked potential (SSEP) are useful non-invasive tests that can detect silent lesions in the central nervous system in patients with clinically suspect MS. In the present study, the BR and SSEP were done in 20 healthy controls and 20 patients with ON. Abnormalities of the SSEP were seen in 20%, and of the BR in 30% of the patients with ON. On combining the results of SSEP and BR studies, 45% of the ON patients were seen to have abnormalities. Over a short period of follow-up, 2 of the 20 ON patients developed clinical MS and both of them had had abnormalities of the BR. These findings suggest that ON proceeding to MS in India may be more common than suspected at present.

Optic neuritis during lactation

The condition called "lactation optic neuritis" has been previously considered a clinical entity of its own. Four women, who developed optic neuritis within 1-12 months while breast-feeding their infants, were investigated ophthalmologically and neurologically in order, to find specific clinical features for this condition. The course of the disorder was similar to classic optic neuritis without lactation. The clinical history and laboratory findings in three of the four patients suggested a demyelinating disorder. It is possible that the decreased immunosuppressive activity just after pregnancy induces the manifestation of an underlying demyelinating disease. The existence of "lactation optic neuritis," however, is questioned as a separate entity of its own. Lactation together with decreased immunosuppression may merely act as a provocateur in the onset of optic neuritis, which in many cases is the first clinical manifestation of incipient multiple sclerosis.

Prognosis of optic neuritis with special reference to cerebrospinal fluid immunoglobulins and measles virus antibodies

Forty-eight patients with optic neuritis (ON), first seen in 1970 to 1973, were neurologically and neuroophthalmologically reexamined after 7 to 10 years. Twenty-seven patients (56%) had probable MS, and 9 (19%) had possible MS. During the attack of ON, the cerebrospinal fluid (CSF) samples and serum/CSF measles antibody ratios were studied. Twenty patients had increased relative immunoglobulin G (IgG) (% of total protein) in their CSF; 19 of these had probable or possible MS. However, 17 of 28 patients with a normal relative IgG value had also developed MS. CSF electrophoresis was abnormal in 20 patients with ON; reexamination showed that 19 had probable or possible MS. Sixteen of 27 patients with normal electrophoresis had also developed MS. Serum/CSF measles antibody ratio had decreased in 19 patients; 13 of these had probable MS and 3 had possible MS. Of 29 patients with a normal measles antibody ratio, 14 had probable MS and 6 had possible MS. The conclusion is that examination of the CSF in ON gives valuable prognostic information because increased relative IgG, abnormal electrophoresis, or a decreased measles antibody ratio implies a high risk of developing MS. A normal CSF does not, however, rule out the possibility of dissemination.

Erythrocyte unsaturated fatty acid test (E-UFA test): a biological test to detect optic neuritis as initial feature of multiple sclerosis

Retrobulbar optic neuritis, though suspicious is not always considered as a possible onset of MS. For this reason we submitted to the E-UFA (erythrocyte unsaturated fatty acid) test, 41 subjects who suffered from one or several episodes of retrobulbar optic neuritis with no other neurological signs. The test was positive in 14 subjects (34, 1%).

Multiple sclerosis: diagnostic usefulness of cerebrospinal fluid

Early, atypical, or progressive cases of multiple sclerosis (MS) may be hard to diagnose. Until recently, assays of the most common abnormalities in cerebrospinal fluid were not available in clinical diagnostic laboratories, but now they can be done with relative ease and adequate standardization. With the newer techniques the CSF is abnormal in more than 90% of clinically definite cases of MS, and determination of such changes can be a major aid in diagnosis. The most common CSF abnormalities are discussed: elevation of immunoglobulin G(IgG), expressed as percentage of total protein; elevation of the IgG/albumin index; and presence of oligoclonal IgG bands. Not only does assessment of these CSF proteins provide an improved aid to diagnosis, but their study may furnish important clues to the cause and pathogenesis of MS as well.

Acute optic neuritis: a virological study in relation to multiple sclerosis

Previous ultrastructural examination of peripheral blood lymphocytes revealed the presence of intranuclear filamentous structures in multiple sclerosis (MS) and in some optic neuritis (ON) patients. The present investigation was undertaken in the attempt to correlate the presence of such structures with the etiology of ON and MS and possibly to demonstrate the viral origin of the filaments. Suitable virological and serological techniques were used to detect and isolate infectious agents from peripheral blood samples and body excretions of 12 monosymptomatic ON patients at their first acute attack. Nevertheless, any efforts to demonstrate the presence of a virus in these patients have been unsuccessful: no evidence of active viral infection was obtained by serological studies of serum and cerebrospinal fluid samples, nor could viral antigens or inclusions be observed by immunofluorescence and cytochemical analysis. Negative results were also obtained from studies performed in parallel on MS patients and various controls. The significance of the failure to isolate infectious agents from either ON and MS patients is discussed.

Optic neuritis in relation to multiple sclerosis

Available estimates of the frequency with which a patient with optic neuritis develops multiple sclerosis range from as low as 13% to as high as 87%. In an effort to obtain a better estimate, a nation-wide study of optic neuritis was carried out in Israel. Patients who fulfilled strict diagnostic criteria of optic neuritis were identified and examined periodically. Between 1955 and 1964, 105 patients were found and on the basis of these, the average annual age-adjusted incidence of optic neuritis in Israel was 0.56 per 10(5) population compared to 1.2 per 10(5) cases of multiple sclerosis per year, i.e. optic neuritis was about half as frequent as multiple sclerosis each year. As with multiple sclerosis, optic neuritis was more common in European immigrants to Israel than Afro-Asian immigrants. During a follow-up interval which ranged from 3.3 to 15.6 years (mean 9.5 years), at least 27 of the 105 patients developed multiple sclerosis (28%). A life-table analysis showed that after 10 years 32.3 +/- 5.6% of patients with optic neuritis would develop multiple sclerosis and, after 14 years, about half would develop multiple sclerosis. Risk of dissemination was highest in those who were youngest when optic neuritis developed. Neither sex nor ethnic background influenced risk significantly. Results of the present study support earlier work using life-table methods carried out in Hawaii which also showed that between 29 and 39% of patients with optic neuritis will develop multiple sclerosis within 10 years of onset. The life-table method is a better predictor of prognosis than newer laboratory techniques such as spinal fluid studies of IgG, kappa-lambda light chain ratios and serum/CSF IgG ratios.

Acute optic neuritis and the prognosis for multiple sclerosis

In a retrospective survey of acute optic neuritis 144 cases in adults were found and, of these, 127 were reviewed, five had died of causes related to multiple sclerosis, and 12 were lost to follow-up. There was a statistically significant seasonal variation in the incidence of optic neuritis. When the life-table method of analysis was used, the probability of developing multiple sclerosis rises to 78% 15 years after an episode of optic neuritis. At review, 49 (73%) of the 67 patients with multiple sclerosis were independent and leading active lives.

The epidemiology of optic neuritis in Finland

Evidence has been presented that optic neuritis partially reflects benign cases of MS which are lost in the epidemiological investigation of the disease. As part of a large epidemiological investigation of MS, 221 patients with pure optic neuritis were identified during the period from January 1, 1967 to December 31, 1971. The mean annual incidence for the whole of Finland was 0.94 per 100,000 population. The female to male ratio was 1.7. The mean age at onset was 31.2 years. The distribution of optic neuritis by counties showed the highest mean annual incidence in the southwestern county of Turku and Pori (1.69) and in the western county of Vaasa (1.68). The prevalence data for MS were highest in these counties. A highly significant deviation from a random distribution according to place at onset and place of birth was obtained. Even the geographical distribution by smaller units, i.e. the combined clerical districts, revealed a firm accumulation to the western districts in the county of Vaasa and to the southwestern districts in the county of Turku and Pori. Thus, optic neuritis showed a similar geographical distribution of Jalasjärvi with several familial cases of MS did not increase the familial percentage when both conditions were considered as a single group. The risk of getting optic neuritis seems to depend on the influence of factors present during childhood. The epidemiological data point to a common factor in the aetiology of optic neuritis and MS.

Virus antibody levels in the cerebrospinal fluid from patients with optic neuritis

Virus antibody levels were studied in the cerebrospinal fluid (CSF) of 58 patients with optic neuritis and 58 control patients with no indication of multiple sclerosis (MS) or infectious disorders of the central nervous system (CNS). The specimens were tested against three different structural components of measles virus with measles hemagglutination inhibition (HI), measles hemolysis inhibition (HLI) and gel precipitation (GP) tests. Measles antibodies occurred in 62 per cent of CSF specimens from patients with optic neuritis, and 21 per cent of the controls. In the specimens from patients with optic neuritis, the positive rate figures were: for rubella HI test 35, parainfluenza-1 HI 16, and Epstein-Barr virus immunofuorescence (IF) 53 per cent. The frequencies in the control group were 10, 10 and 26 per cent, respectively. Serum/CSF antibody ratios below 80 occurred in measles tests in 45 per cent of patients with optic neuritis and 16 per cent of the control group. Some patients with optic neuritis (but none from the control group) had a reduced serum/CSF antibody ratio in more than one measles antibody test, The patients with optic neuritis had a higher frequency of low serum/CSF albumin ratios indicating blood brain barrier damage, There were, however, several patients with a normal serum/CSF albumin ratio but low serum/CSF immunoglobulin G and measles antibody ratios. This supports the hypothesis that local production of measles antibodies takes place in CNS in some patients with optic neuritis as well as in MS patients. The CSF specimens were further tested against 12 other viruses and mycoplasma pneumoniae complement fixation, but there were no positive specimens. New CSF specimens were taken from five patients during optic neuritis, and from seven patients later on during the follow-up because of the appearance of new neurological symptoms. There were no changes in virus antibody levels, except for two patients with an increase of measles virus antibody titres.

Symptoms, signs and early course of optic neuritis

The study was an anlysis of the early course of optic neuritis based on the case histories of 185 patients, 57% of whom were females and 43% males. More than half of the patients suffered from multiple sclerosis. In 28% of the patients the etiology remained unknown. The most common initial symptom was acute decrease in visual acuity, but in 25% the onset was subacute or slow. Pain occured in 62% and preceded decrease in visual acuity in 16% of the cases. The initial attack was unilateral in 70% and bilateral in 30% of the patients. On admission, in 64% of the involved eyes, visual acuity was poor and in 73% the defect in the visual field involved the central field. The optic disc was normal in 46%, blurred and /or hyperaemic in 20%, oedematous in 23% and in 11% there was temporal or total pallor already on admission. The last finding was common in patients with bilateral optic neuritis with a slow onset. Six months after admission visual acuity was good or excellent in 56% and the visual field was normal in 45% of the involved eyes.

Later course and prognosis of optic neuritis

The study was a re-examination of 176 patients with optic neuritis. The follow-up period was for 38 patients, 6-12 months, for 52 patients, 1-5 years and for 86 patients, 6-24 years from the initial attack of optic neuritis. In 66% of the involved eyes visual acuity had again become good or excellent, but in 25% it was poor. The visual field was normal in only 38%, in 30% there was an absolute or relative central defect and in 31% a paracentral or peripheral defect. Recurrent attacks of optic neuritis occurred in one fourth of the patients and was a common finding in MS patients. Nineteen per cent of the eyes had suffered from more than one attack. Visual acuity was good or excellent in more than half, but the visual field was normal in only 29% of the eyes with more than one attack of optic neuritis. The frequency of bilateral involvement was high at the end of the follow-up period, 44% of patients had both eyes involved by optic neuritis. In 47 patients the initial attack was bilateral optic neuritis and 34% of these patient had permanently poor vision in both eyes. The initial attack was unilateral in 30 patients but the other eye became involved later. In 26% of all patients with bilateral involvement, visual acuity was permanently poor in both eyes. Bilateral papillitis was a common manifestation in young patients and in this age group the disease had a tendency towards good recovery.