One of today’s sessions placed the focus squarely on neuromyelitis optica (more recently expanded to be called neuromyelitis optica spectrum disorder, or NMOSD), a rare autoimmune disorder of the central nervous system (CNS) in which the spinal cord and/or optic nerves are attacked and damaged by specific antibodies. While far less common than MS, NMOSD can sometimes be confused with MS due to similar clinical features, although NMOSD attacks are often more severe than MS relapses. Two of the most common symptoms experienced by people living with NMOSD are inflammation of the optic nerve (called optic neuritis) which causes blurring or loss of vision in one or both eyes, and inflammation of the spinal cord (transverse myelitis), which can lead to a host of symptoms including arm and leg weakness, muscle spasms, bladder and bowel problems, and pain.
Since NMOSD and MS are fundamentally different diseases that require their own unique set of diagnostic criteria and treatment strategies, the panel brought together researchers at the forefront of NMOSD research to present their latest findings with the view to improve our understanding and management of the disease.
The session opened with a presentation by Professor Claudia Lucchinetti (Mayo Clinic, USA), recipient of the prestigious John Dystel prize for her exceptional contributions to understanding how MS and allied conditions like NMOSD damage the tissues of the brain and spinal cord. Prof. Lucchinetti has played a pivotal role in teasing out NMOSD from MS as a distinct disorder by describing the immunological features that target CNS tissues in NMOSD that are unique compared to MS. Her research, in turn, has laid the groundwork for the discovery of an antibody biomarker for a specific type of protein (called aquaporin-4) in certain brain cells surrounding blood vessels that can help identify people at risk for NMOSD.
Dr. Ingo Kleiter (Ruhr-University Bochum, Germany) presented data from a retrospective study of patient records from a nation-wide registry (Neuromyelitis Optica Study Group) encompassing 185 individuals to describe in detail the characteristics of NMOSD, available therapies (including high dose intravenous steroids, plasma exchange and immunoadsorption), and efficacy of those therapies based on ability to lead to remission. The team found that those with NMOSD attacks causing transverse myelitis and optic neuritis in both eyes experienced worse remission rates than those who only had optic neuritis in one eye. Importantly, transverse myelitis responded best to plasma exchange and immunoadsorption as a first treatment course compared to the more common intravenous steroid therapy. This information will allow clinicians to make more informed decisions when deciding the best treatment strategy for people living with NMOSD.
While the ratio of women affected by MS compared to men can be between three and four to one, the ratio in NMOSD can be as high as 9:1. Dr. Riley Bove (University of California San Francisco) described the relationship between sex-specific hormones and disease features in women with NMOSD at 8 clinical centres in the US. Among her team’s findings was that women with a greater number of earlier pregnancies overall had a later onset of first symptoms, although she admitted that the age of the study participants could be a confounding factor and that definitive conclusions were difficult to make. She also found that the use of hormonal contraceptives and hormonal therapy were associated with an earlier age of NMOSD onset but overall lower disability. This information lays the foundation for providing more comprehensive care to women who have or are at risk of developing NMOSD and can lead to promising avenues for hormone-centred therapies.
The seminar went on to discuss the features of NMOSD in children. Doctoral student Jessica Hauser in Dr. Timothy Lotze’s team (Texas Children’s Hospital) presented data describing the relationship between lesions in the CNS captured with imaging techniques and clinical features in pediatric NMOSD. Her work showed that in addition to widespread symptoms of transverse myelitis and optic neuritis, the pediatric study group also experienced other atypical clinical features that, in some cases, could lead to symptoms like seizures, difficulty communicating (expressive aphasia) and altered mental status such as confusion and disorientation. These observations were not altogether surprising given that lesions were also seen in the CNS outside of the usual optic nerve and spinal cord. These findings give important weight to the understanding that, much like in MS, children are not simply miniature adults and it is important to treat and manage NMO in children in a manner that is unique compared to adults.
More updates on the AAN meeting to follow. In the meantime, don’t forgot to follow live updates on Twitter @Dr_KarenLee