Rituximab improves not only back stiffness but also “stiff eyes” in stiff person syndrome: Implications for immune-mediated treatment

• Published in: Journal of the neurological sciences 2020-01, Vol.408, p.116506, Article 116506
• Main Authors: Kodama, Satoshi, Tokushige, Shin-ichi, Sugiyama, Yusuke, Sato, Kazuya, Otsuka, Juuri, Shirota, Yuichiro, Hamada, Masashi, Iwata, Atsushi, Toda, Tatsushi, Tsuji, Shoji, Terao, Yasuo
• Format: Article
• Language: English
• Subjects: Adult; Back Muscles - drug effects; Back Muscles - physiology; Burst neurons; Eye-Tracking Technology; Glutamic acid decarboxylase (GAD); Humans; Immunologic Factors - pharmacology; Immunologic Factors - therapeutic use; Latch circuit; Male; Omnipause neuron; Rituximab - pharmacology; Rituximab - therapeutic use; Saccades - drug effects; Saccades - physiology; Slow saccade; Stiff person plus; Stiff-Person Syndrome - drug therapy; Stiff-Person Syndrome - physiopathology; Video-based eye tracking system
• ISSN: 0022-510X; 1878-5883
• DOI: 10.1016/j.jns.2019.116506

Stiff person syndrome (SPS) is usually characterized by truncal muscle rigidity and episodic painful spasms, but it sometimes appears with ocular symptoms called “stiff eyes”. We recorded saccade movements in an SPS patient manifesting with “stiff eyes” conditions with slow saccade velocity and evaluated the effect of immunotherapy including rituximab on saccade parameters. We repeatedly conducted saccade eye recordings using video-based eye tracking system on a 42-year-old male SPS patient with slow saccade. The velocity and onset latency of visual guided saccades (VGS) were measured at each recording. Because VGS velocity is affected by saccade amplitude, estimated peak velocity (Vmax) was also calculated by taking the relationship between the velocity and the amplitude of saccade into account. The mean VGS velocity improved significantly after two courses of rituximab administration compared with its lowest value. The estimated Vmax decreased as the clinical manifestations worsened, but it increased after rituximab administration. Other neurological symptoms in this patient such as muscle rigidity and gait instability also improved after the treatment. Slow saccade in a “stiff eyes” patient improved after rituximab administration. Our study also indicated that the saccade eye recording is useful for evaluating the clinical condition of SPS when it is complicated with ocular symptoms. •Slow saccade in stiff person syndrome (SPS) improved after rituximab administration.•Rituximab may be effective for ocular symptoms in SPS.•Saccade eye recording can be a useful measure for evaluating ocular symptoms in SPS.