Mild Bilateral Internuclear Ophthalmoplegia: The Diagnostic Role of the Vertical Posterior Canal Vestibulo-Ocular Reflex in Acute Brainstem Demyelination, a Clinical-Radiologic Correlation

BACKGROUND

The ocular signs of internuclear ophthalmoplegia (INO) with slow, restricted adduction of one eye and abduction nystagmus of the contralateral eye are easily recognized and have a high localizing/lateralizing value. However, subtle INO is difficult to diagnose. Recent reports identified novel vestibular abnormalities in unilateral and bilateral INO. Frequent findings include decreased horizontal and posterior canal gains, and generally relative sparing of both anterior canals. We studied one patient with a subtle bilateral INO, performed serial quantitative saccade (QS) and video head impulse test (vHIT), and correlated clinical-radiological findings caused by acute demyelination.

METHODS

Single case study of a 30-year-old man presented with 1 week of painless, binocular, horizontal diplopia in left gaze. We performed 3 serial neurological examination, QS, vHIT, and clinical-MRI correlation (1 pretreatment and 2 post steroid treatment).

RESULTS

We found bilateral slow adducting, clinically positive posterior canal HITs, and borderline abducting saccade velocity, without abducting nystagmus. The videonystagmography with fixation block showed bilateral horizontal gaze evoked nystagmus, and vHIT testing confirmed decreased right horizontal and bilateral posterior canal gains. The abnormalities resolved after steroid treatment. MRI showed acute bilateral medial longitudinal fascicle demyelinating lesions.

CONCLUSIONS

A bilaterally positive, posterior, canal HIT and slow adduction saccades are localizing findings in bilateral INO, even in the absence of abduction nystagmus. Quantitative confirmation of these findings suggest most frequently an ischemic or demyelinating disorder and are a compelling indication for MRI. This case shows value to testing multiaxial head impulses and performing QS and vHIT in brainstem lesions.

MRI topography of lesions related to internuclear ophthalmoplegia in patients with multiple sclerosis or ischemic stroke

BACKGROUND AND PURPOSE

Internuclear ophthalmoplegia is a dysfunction of conjugate eye movements, caused by lesions affecting the medial longitudinal fasciculus (MLF). Multiple sclerosis (MS) and ischemic stroke represent the most common pathophysiologies. While magnetic resonance imaging (MRI) allows for localizing lesions affecting the MLF, comprehensive comparative studies exploring potential different spatial characteristics of lesions affecting the MLF are missing until now.

METHODS

We retrospectively investigated MRI examinations of 82 patients (40 patients with MS and 42 patients with ischemic stroke). For lesion localization, the brainstem was segmented into (1) ponto-medullary junction, (2) mid pons, (3) upper pons, and (4) mesencephalon.

RESULTS

Corresponding lesions affecting the MLF were observed in 29/40 (72.5%) MS and 38/42 (90.5%) stroke patients. Compared to stroke patients, MS patients had significantly more lesions in multiple locations (P < .001). Stroke patients showed more lesions at the level of the mesencephalon (P < .001), while lesions at the level of the ponto-medullary junction, mid, and upper pons did not statistically differ between the groups.

CONCLUSION

Our results demonstrate that multiple lesions affecting the MLF make inflammatory-demyelination due to MS more likely, while lesion localization at the level of the mesencephalon favors ischemia.

Eye movements in demyelinating, autoimmune and metabolic disorders

PURPOSE OF REVIEW

In the last three decades, the use of eye movements and vestibular testing in many neurological disorders has accelerated, primarily because of practical technologic developments. Although the acute vestibular syndrome is a prime example of this progress, more chronic neurologic and systemic disorders have received less attention. We focus here on recent contributions relating vestibular and ocular motor abnormalities in inflammatory, demyelinating, metabolic, and peripheral nervous system disorders RECENT FINDINGS: Vestibular abnormalities have been identified in acute demyelinating neuropathies (AIDP), in novel genetic mutations responsible for CANVAS (cerebellar ataxia, neuropathy vestibular areflexia syndrome), and in other inherited neuropathies (variants of Charcot-Marie-Tooth disease). In addition, there are differentiating characteristics between the most common CNS demyelinating disorders: multiple sclerosis and neuromyelitis optica (NMO). We summarize new information on Vitamin D metabolism in benign paroxysmal positional vertigo (BPPV), followed by a brief review of the vestibular and ocular motor findings in Wernicke's encephalopathy. We conclude with findings in several paraneoplastic/autoimmune disorders.

SUMMARY

This literature review highlights the impact of a careful vestibular and ocular motor evaluation in common neurologic disorder, not only for the initial diagnosis but also for monitoring disease and rehabilitation. A careful examination of eye movements and vestibular function, supplemented with new video techniques to quantify the findings, should be part of the standard neurologic examination.

Three-Dimensional Identification of the Medial Longitudinal Fasciculus in the Human Brain: A Diffusion Tensor Imaging Study

Background: The medial longitudinal fasciculus (MLF) interacts with eye movement control circuits involved in the adjustment of horizontal, vertical, and torsional eye movements. In this study, we attempted to identify and investigate the anatomical characteristics of the MLF in human brain, using probabilistic diffusion tensor imaging (DTI) tractography. Methods: We recruited 31 normal healthy adults and used a 1.5-T scanner for DTI. To reconstruct MLFs, a seed region of interest (ROI) was placed on the interstitial nucleus of Cajal at the midbrain level. A target ROI was located on the MLF of the medulla in the reticular formation of the medulla. Mean values of fractional anisotropy, mean diffusivity, and tract volumes of MLFs were measured. Results: The component of the MLF originated from the midbrain MLF, descended through the posterior side of the medial lemniscus (ML) and terminated on the MLF of medulla on the posterior side of the ML in the medulla midline. DTI parameters of right and left MLFs were not significantly different. Conclusion: The tract of the MLF in healthy brain was identified by probabilistic DTI tractography. We believe this study will provide basic data and aid future comparative research on lesion or age-induced MLF changes.

Eye Movement Abnormalities in Multiple Sclerosis: Pathogenesis, Modeling, and Treatment

Multiple sclerosis (MS) commonly causes eye movement abnormalities that may have a significant impact on patients’ disability. Inflammatory demyelinating lesions, especially occurring in the posterior fossa, result in a wide range of disorders, spanning from acquired pendular nystagmus (APN) to internuclear ophthalmoplegia (INO), among the most common. As the control of eye movements is well understood in terms of anatomical substrate and underlying physiological network, studying ocular motor abnormalities in MS provides a unique opportunity to gain insights into mechanisms of disease. Quantitative measurement and modeling of eye movement disorders, such as INO, may lead to a better understanding of common symptoms encountered in MS, such as Uhthoff’s phenomenon and fatigue. In turn, the pathophysiology of a range of eye movement abnormalities, such as APN, has been clarified based on correlation of experimental model with lesion localization by neuroimaging in MS. Eye movement disorders have the potential of being utilized as structural and functional biomarkers of early cognitive deficit, and possibly help in assessing disease status and progression, and to serve as platform and functional outcome to test novel therapeutic agents for MS. Knowledge of neuropharmacology applied to eye movement dysfunction has guided testing and use of a number of pharmacological agents to treat some eye movement disorders found in MS, such as APN and other forms of central nystagmus.

Evidence for Plastic Processes in Migraine with Aura: A Diffusion Weighted MRI Study

Background: Formerly white matter abnormalities in a mixed group of migraine patients with and without aura were shown. Here, we aimed to explore white matter alterations in a homogeneous group of migraineurs with aura and to delineate possible relationships between white matter changes and clinical variables.

Methods: Eighteen patients with aura, 25 migraine patients without aura and 28 controls were scanned on a 1.5T MRI scanner. Diffusivity parameters of the white matter were estimated and compared between patients’ groups and controls using whole-brain tract-based spatial statistics.

Results: Decreased radial diffusivity (p < 0.036) was found bilaterally in the parieto-occipital white matter, the corpus callosum, and the cingular white matter of migraine with aura (MwA) patients compared to controls. Migraine without aura (MwoA) patients showed no alteration compared to controls. MwA compared to MwoA showed increased fractional anisotropy (p < 0.048) in the left parieto-occipital white matter. In MwA a negative correlation was found between axial diffusivity and disease duration in the left superior longitudinal fascicle (left parieto-occipital region) and in the left corticospinal tract (p < 0.036) and with the number of the attacks in the right superior longitudinal fascicle (p < 0.048).

Conclusion: We showed for the first time that there are white matter microstructural differences between these two subgroups of migraine and hence it is important to handle the two groups separately in further researches. We propose that degenerative and maladaptive plastic changes coexist in the disease and the diffusion profile is a result of these processes.

Effects of Sport Climbing on Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune and neurodegenerative disease of the central nervous system (CNS) with different types of disease courses (relapsing-remitting, secondary-progressive, primary progressive) that leads to physical as well as mental disability. The symptoms comprise paresis or/and paralysis, ataxia, bladder dysfunction, visual problems as well as effects on cognition. There is limited data regarding the possible effects of sport climbing respectively therapeutic climbing on patients with MS. Sport climbing offers many potentially beneficial effects for patients with MS since there are effects on coordination, muscular strength, and cognition to name the most relevant ones. Also, disease models in rodents point toward such positive outcomes of climbing. Therefore, we assessed the currently available research literature on general effects of physical exercise, impact of climbing on body and mind and therapeutic climbing for prevention or therapy for the treatment of MS. The sparse published controlled trials that investigated this sport activity on different groups of patients with neurological or geriatric diseases grossly differ in study design and outcome parameters. Nevertheless, it appears that climbing offers the opportunity to improve some of the symptoms of patients with MS and can contribute to an enhanced quality of life.

Multiple sclerosis: integration of modeling with biology, clinical and imaging measures to provide better monitoring of disease progression and prediction of outcome

Multiple Sclerosis (MS) is a major cause of neurological disability in adults and has an annual cost of approximately $28 billion in the United States. MS is a very complex disorder as demyelination can happen in a variety of locations throughout the brain; therefore, this disease is never the same in two patients making it very hard to predict disease progression. A modeling approach which combines clinical, biological and imaging measures to help treat and fight this disorder is needed. In this paper, I will outline MS as a very heterogeneous disorder, review some potential solutions from the literature, demonstrate the need for a biomarker and will discuss how computational modeling combined with biological, clinical and imaging data can help link disparate observations and decipher complex mechanisms whose solutions are not amenable to simple reductionism.