1. Adult periodic alternating nystagmus masked by involuntary head movements: a case report
- Author
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Kaski, DN, Haider, S, Male, A, Liu, F, Radunovic, A, Cordivari, C, Bhatia, K, and Bronstein, AM
- Subjects
Science & Technology ,DISORDERS ,Clinical Neurology ,Neurosciences ,periodic alternating nystagmus ,1103 Clinical Sciences ,head tremor ,ATAXIA ,rhombencephalitis ,psychogenic ,vestibulo-ocular reflex ,1701 Psychology ,Neurosciences & Neurology ,oscillopsia ,1109 Neurosciences ,Life Sciences & Biomedicine - Abstract
A 20-year-old previously well female presented with a history of abrupt onset recurrent episodic (seconds) “dizziness” characterized by a shimmering of the world in front of her. By day 3 she began to experience a constant sensation of vertigo, oscillopsia, mild headache, and prominent vomiting. She was afebrile, had no neck stiffness, but described photophobia. She had gradually developed an involuntary mild side-to-side continuous head movement by day 3. On day 6 there was a constant “no-no” head movement with variable frequency (circa. 2–4 Hz) and amplitude (circa. 15° peak- to-peak) and initially had a fast phase component to the right, with occasional oblique movements (Video S1 in Supplementary Material). The family reported that the movement disappeared during sleep. On admission to hospital, there was right-beating nystagmus (RBN) in the primary position intensifying on right gaze and also apparent on upgaze (Video S1 in Supplementary Material). The intensity of the nystagmus was enhanced during positional maneuvers, without a change in nystagmus direction. Oculographic recordings were not available acutely. The gait was unsteady, with asymmetric step length, inconsistent foot placement, and variable left foot intorsion, sug- gesting a functional (psychogenic) etiology (Video S2 in Supplementary Material). There was no limb ataxia, and no myoclonus. Ten days after the original assessment the head movements worsened dramatically, rendering interpretation of the eye movements difficult ( Figure 1A ; Video S3 in Supplementary Material), but the patient continued to complain of oscillopsia, even when the examiner attempted to restrain the head manually (the patient did not consent to the use of a bite bar). The head tremor resolved immediately on day 21 after symptom onset with subtherapeutic 50 mouse units of abobotulinumtoxin A applied to the levator scapulae muscles bilaterally. With the head now still it became possible to visualize the eye movements revealing periodic alternating nystagmus (PAN) with a cycle of approximately 90 s, and a null phase of 2 s ( Figures 1B,C ; Video S4 in Supplementary Material). An MRI brain scan on day 6 showed bilateral symmetrical superior cerebellar peduncle atrophy, thinning of the anterior cerebellar structures, and enlargement of the fourth ventricle ( Figure 2 ), unchanged at 6-month follow-up. Initial cerebrospinal fluid (CSF) analysis revealed normal protein and no cells. Oligoclonal bands were absent in CSF and serum, and full viral PCR negative in the CSF. A vasculitic and paraneoplastic screen, whole body PET-CT, spinocerebellar ataxia 1, 2, 3, 6, 7, 8, and 12 gene testing, and autoimmune screen including anti-GAD and anti-Gq1b antibodies were normal. Pure tone audiometry on day 13 was normal, and vestibular responses to impulse chair rotation, taking into consideration the involuntary head oscillations, were normal and symmetrical (also day 13).
- Published
- 2018