While the spectrum of ocular motor abnormalities in multiple sclerosis (MS) has been previously reported (1-4), the course of ophthalmoplegia as a clinically isolated demyelinating syndrome (CIS) has been less well characterized (5-7). Knowledge regarding the evolution of ophthalmoplegia in CIS is essential in establishing diagnostic criteria and developing prognostic and therapeutic recommendations. We identified a cohort of patients with isolated ophthalmoplegia from focal demyelination. While it is clear that the risk of developing clinically definite multiple sclerosis (CDMS) following CIS depends on multiple factors, especially the presence of multiple demyelinating lesions on brain MRI (8), there is little information regarding whether the severity or course of ophthalmoplegia in CIS might be predictive of progression to CDMS.
Approval from the University of Illinois Institutional Review Board was obtained. All cases of ophthalmoplegia presenting to our neuro-ophthalmology clinic between July 2003 and July 2007 were reviewed, and patients meeting eligibility criteria were selected (Table 1). Follow-up of selected cases continued until January 2010. All patients underwent neurologic and neuroophthalmologic examination with documentation of eye position in primary gaze, assessment of saccadic pursuit and vergence eye movements, and qualification of prismatic correction. In all cases, data from the last recorded measurement were used as the final measurement. Eye movements were not recorded at every patient follow-up visit between first and final measurements.
Patients were included only if brain MRI findings correlated with the ocular motor disorder. At our institution, MRI was performed with a Siemens 1.5 Tesla Magnetom Vision/Plus and used a slice thickness of 5 mm with no gap, including T1, T2, FLAIR, diffusion weighted imaging, and postcontrast sequences. Outside imaging used a 1.5-T MRI and included the same sequences. All films were reviewed by a neuroophthalmologist and neuroradiologist, both of whom had clinically relevant information prior to interpreting the scan. All patients had a comprehensive metabolic panel, complete blood count and differential, sedimentation rate, and antinuclear antibody. Follow-up MRI, lumbar puncture, and treatment decisions depended on the clinical course of each patient.
Records of 327 consecutive cases presenting with diplopia to our neuro-ophthalmology clinic were reviewed. Of these, 17 (5%) met criteria for CIS. “However, 4 of these 17 patients did not have at least 10 months of follow-up, and 3 did not have a brain MRI lesion corresponding to their clinical deficit.” Of the remaining 10 patients, the mean age at presentation was 29.8 years (range, 18-46 years; median, 31.5 years), and 7 were women.
Six of 10 patients had an isolated sixth nerve palsy (Fig. 1). The range of esotropia in primary position was 2-20 prism diopters, and all worsened with abduction of the paretic eye. Three patients had a unilateral internuclear ophthalmoplegia (INO), and 1 patient had a one-and-a-half syndrome. All cases of INO had nystagmus of the abducting eye, and none had skew deviation.
Mean total patient follow-up was 43.9 months (median, 28 months; range, 10-122 months). Eye movement measurements were recorded on at least 2 occasions. Range between initial and final measurements was 1-122 months. At final examination, all 10 patients were orthophoric in primary position. Table 2 summarizes the clinical features of our patient cohort.
In 3 patients with sixth nerve palsy, there was a residual ophthalmoplegia ranging from 6 to 16 diopters in the direction of the paretic muscle over 30-98 months of follow-up. In 1 case (Case 2), the esotropia increased to 12 prism diopters in primary position and 25 prism diopters in left gaze within the first 3 weeks before improving.
All 3 patients who presented with INO experienced full recovery. Case 9 presented with a one-and-a-half syndrome with impaired right gaze and an adduction deficit in the right eye. During the course of follow-up, the one-and-a-half syndrome resolved, but the patient later developed a left sixth nerve palsy.
Of the 10 patients, 7 had other asymptomatic lesions on brain MRI at presentation. These MRI abnormalities included T1 hypointensities (black holes), enhancing lesions, and cerebellar hyperintensities, all occurring in presumably noneloquent areas of the parenchyma. The maximum number of asymptomatic white matter lesions was 24. There was no relationship between the clinical presentations either to the size of the symptomatic lesion or to lesion proximity to the ocular motor cranial nerve nucleus.
During the study period, 4 patients developed a second clinical attack diagnostic of CDMS. Case 2 developed a symptomatic INO, and Cases 6, 7, and 10 developed optic neuritis. Three patients who received steroids and 1 of 3 who did not receive steroids developed CDMS. All 3 patients with a residual ophthalmoplegia had received steroids during their initial attack.
Cases 1, 5, and 9 developed new white matter lesions on brain MRI without progressing to CDMS. Of the 4 patients who developed CDMS, 3 (Cases 2, 6, and 10) had asymptomatic white matter lesions on brain MRI at presentation. Case 7 initially had no asymptomatic brain MRI lesions; however, over 24 months, Case 7 developed 6 new brain MRI lesions and a second clinical attack.
Four patients underwent spinal tap. One patient who had oligoclonal bands (OCB) developed CDMS. Three patients with no OCB have not developed MS (range of follow-up: 18-102 months).
Regarding 3 patients with CIS who would otherwise have met inclusion criteria, except they lacked a corresponding symptomatic brainstem MRI lesion, 2 had other asymptomatic brain MRI lesions consistent with demyelination. These 2 patients have progressed to CDMS, while the 1 patient with a normal brain MRI did not. The ophthalmoplegia in all 3 of these patients improved over time.
Relapsing-remitting MS involves both inflammatory and neurodegenerative processes. While the underlying pathophysiology probably involves both genetic and environmental factors, specific triggers for the onset and clinical course of the disease are unknown. Although CIS often represents early MS (9), this is not always the case. Late MS is associated with progressive atrophy and axonal loss, with fewer relapses and remissions than the predominant inflammatory attacks of early MS (10). For this reason, data specifically regarding the course of CIS ophthalmoplegia may help determine if there are clinical findings or test results that could distinguish it from ophthalmoplegia due to MS.
MS plaques with the brainstem causing diplopia may involve the nuclear or fascicular portion of ocular motor cranial nerves or the medial longitudinal fasciculus. The most common deficit in our series was sixth nerve palsy followed by INO and one-and-a-half syndrome. Our series did not include patients with a third or fourth nerve palsy, which is uncommon in MS (11,12), or a skew deviation, which often occurs with INO.
The ophthalmoplegia improved in all our patients, and at last examination, they were all orthophoric in primary position. Three patients continued to have a residual phoria after 30-98 months of follow-up. This high rate of improvement correlates with other reports of CIS (13) and suggests that ophthalmoplegia, which worsens over time, should be reevaluated for causes other than demyelination. Our results also indicate that initial treatment for diplopia should be prismatic correction, and surgical correction, if considered, should not be performed until repeat examinations show that eye position is stable.
Steroids given at onset of ophthalmoplegia (Table 2) did not appear to alter the clinical outcome. The 3 patients not given steroids were orthophoric at their last evaluation. All 3 patients with residual phoria in lateral gaze received steroids initially. Because follow-up testing intervals were variable, it is unclear if steroids decrease symptom duration (14).
The American Academy of Neurology has a practice parameter regarding the use of steroids to treat ON (15). While no such protocol exists for brainstem demyelination, it is our practice to discuss treatment options with our patients and reach a shared conclusion.
To be included in our series, all patients had lesions on MRI correlating to their clinical deficit. In patients who met inclusion criteria except for not having a visible MRI lesion, INO was the most common presentation. In other series, MRI lesion detection rate for INO varies from 45% to 100% (16).
It will be notable, as more case series are reported, to determine if there is a correlation between the size and location of the demyelinating lesion on MRI and the degree of ophthalmoplegia. In this underpowered series, we were unable to find a correlation with size of the lesion on MRI to the clinical syndrome or the degree of ophthalmoplegia. Although a few lesions appeared to involve the abducens nucleus, no gaze palsy was observed. We and others note that T2 and proton density sequences provide the best views of the brainstem (17).
A limitation of our study was that only 1.5-T MRI was used. The use of 3-T MRI would likely have increased the number of patients in our cohort, as symptomatic lesions unseen with 1.5-T MRI may have been visible with a stronger magnet. Other limitations include retrospective analysis, lack of uniformity in follow-up and measurement interval, and variation in treatment with steroids and immunomodulatory agents.
Initiating treatment after a first demyelinating event may delay the onset of CDMS (9). However, there continues to be a debate regarding the appropriate time to start MS therapies (18). We discuss this controversy with our patients and engage them in the decision-making process. Some start immunomodulation after an initial demyelinating event, while others elect to be monitored clinically or for MRI changes. Analysis of more patients with CIS presenting as ophthalmoplegia will hopefully clarify features predictive of the clinical course. For example, in optic neuritis, the presence of a macular star or peripapillary hemorrhages argues against future demyelination. Brainstem lesions in general are associated with increased conversion from CIS to CDMS and with greater disability (19). More cases should be studied to determine if the specific features of ophthalmoplegia in CIS differentiate progression to CDMS or higher disability. In our series, diplopia caused by CIS with a correlating lesion on MRI improved over time, independent of conversion to CDMS.
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