Frequency and characterization of movement disorders in anti-IgLON5 disease

Objective: Anti-IgLON5 disease is a recently described neurological
disease that shares features of autoimmunity and neurodegeneration.
Abnormal movements appear to be frequent and important but have not been
characterized and are under-reported. Here we describe the frequency and
types of movement disorders in a series of consecutive patients with this
disease. Methods: In this retrospective, observational study, the presence
and phenomenology of movement disorders were assessed with a standardized
clinical questionnaire. Available videos were centrally reviewed by three
experts in movement disorders. Results: Seventy two patients were
included. In 41 (57%) the main reason for initial consultation was
difficulty walking along with one or several concurrent movement
disorders. At the time of anti-IgLON5 diagnosis, 63 (87%) patients had at
least one movement disorder with a median of three per patient. The most
frequent abnormal movements were gait and balance disturbances (52
patients, 72%), chorea (24, 33%), bradykinesia (20, 28%), dystonia (19,
26%), abnormal body postures or rigidity (18, 25%), and tremor (15, 21%).
Other hyperkinetic movements (myoclonus, akathisia, myorhythmia, myokymia,
or abdominal dyskinesias) occurred in 26 (36%) patients. The craniofacial
region was one of the most frequently affected by multiple concurrent
movement disorders (23 patients, 32%) including dystonia (13), myorhythmia
(6), chorea (4) or myokymia (4). Considering any body region, the most
frequent combination of multiple movement disorders consisted of gait
instability or ataxia associated with craniofacial dyskinesias or
generalized chorea observed in 31(43%) of patients. In addition to
abnormal movements, 87% of patients had sleep alterations, 74% bulbar
dysfunction, and 53% cognitive impairment. Fifty-five (76%) patients were
treated with immunotherapy, resulting in important and sustained
improvement of the movement disorders in only seven (13%) cases.
Conclusions: Movement disorders are a frequent and leading cause of
initial neurological consultation in patients with anti-IgLON5 disease.
Although multiple types of abnormal movements can occur, the most
prevalent are disorders of gait, generalized chorea, and dystonia and
other dyskinesias that frequently affect craniofacial muscles. Overall,
anti-IgLON5 disease should be considered in patients with multiple
movement disorders, particularly if they occur in association with sleep
alterations, bulbar dysfunction, or cognitive impairment.