Ki-Bum Sung

Underdevelopment of the postural control system in autism

Objective: To determine if abnormalities exist in postural control in autism and if they are related to age. Methods: Dynamic posturography was performed in 79 autistic individuals without mental retardation and 61 healthy volunteers between ages 5 and 52 years. Both the sensory organization and the movement coordination portions of the test were performed. Results: The autistic subjects had reduced postural stability (p = 0.002). Examination of age effects revealed that the development of postural stability was delayed in the autistic subjects (p < 0.001) and failed to achieve adult levels (p = 0.004). Postural stability was reduced under all conditions but was clinically significant only when somatosensory input was disrupted alone or in combination with other sensory challenges (mean reduction in stability of 2.6 ± 1.0 for the first three conditions without somatosensory disruption vs 6.7 ± 2.7 for the last three conditions with somatosensory disruption), indicating problems with multimodality sensory integration. Conclusions: The evidence from this and studies of the motor system suggests more general involvement of neural circuitry beyond the neural systems for social behavior, communication, and reasoning, all of which share a high demand on neural integration of information.

Isolated axial lateropulsion with ipsilesional subjective visual vertical tilt in caudal lateral medullary infarction

The isolated body lateropulsion has been well recognized in caudal lateral medullary infarction and postulated to result from the involvement of ipsilateral dorsal spinocerebellar tract which is known to convey proprioception of trunk and legs. However, there has been no case accompanied by the tilt of the subjective visual vertical in caudal lateral medullary infarction. Recently, it has been suggested that a lesion in the ipsilateral graviceptive vestibulothalamic pathway can lead to alteration of subjective visual vertical without ocular tilt reaction in various brainstem lesions. Here we describe two cases of caudal lateral medullary infarction with ipsilesional body lateropulsion and subjective visual vertical tilt but without limb ataxia or ocular tilt reaction. It could be hypothesized that the ascending graviceptive information from the spinal cord may run adjacent to the dorsal spinocerebellar tract or perception of the visual vertical can be influenced by ascending spinal proprioception.

Video head impulse findings in the ictal period of vestibular migraine

Vestibular migraine (VM) manifests as central or peripheral vestibular dysfunction during vertigo attacks [1]. However, no studies have reported the findings of video head impulse tests (vHIT) during the ictal period of VM. Herein, we report unique findings of vHIT in a patient with VM during a vertigo attack. A 40-year-old man presented with positional vertigo without auditory symptoms. Sitting up from the supine position, but not vice versa, aggravated his vertigo. Over a 4-year period, he had suffered from several episodes of vertigo lasting from 48 to 72 h that was followed by a migrainous headache with photophobia, phonophobia, and nausea for 1–2 days. He reported that the clinical features of this vertigo were quite similar to previous recurrent attacks. His symptoms met the Barany Society’s diagnostic criteria for vestibular migraine [2]. His father and older sister also had recurrent episodes of headache without vertigo. On examination, the patient veered slightly to the left and revealed spontaneous nystagmus beating rightward and torsional, with the upper poles of the eyes beating toward the right ear (clockwise) (Fig. 1a). Bedside HIT was unremarkable. Positional maneuvers augmented the spontaneous nystagmus and induced a down-beating component during seated head bending. Adopting a chin-up position while sitting or lying down reversed the patient’s nystagmus into beating leftward, upward, and torsional, with the upper poles of the eyes beating toward the left ear (counterclockwise). Horizontal head shaking augmented the spontaneous nystagmus. Vertigo and positional nystagmus did not improve after repeated canalith-repositioning maneuvers. Caloric testing revealed 37.5% left side canal paresis (Fig. 1b). Sinusoidal harmonic acceleration tests revealed decreased vestibulo–ocular reflex (VOR) gain, deviation to the left side, and phase lead (Fig. 1c). Step-velocity test showed decreased time constant of the VOR on the left side than on the contralateral side (8 vs. 14 s). VOR cancelation with visual fixation was normal. vHIT revealed covert saccades and early acceleration and premature deceleration (EAPD) during stimulation of the left horizontal (HC) and left posterior semicircular canal (PC), respectively [3] (Fig. 1d). Fundus photography showed counterclockwise ocular torsion (Fig. 1e, 12.8° in the left eye, − 11.1° in the right eye; normal range: 0°–12.6°; positive values indicate extorsion). Vestibular-evoked myogenic potentials, pure tone audiometry, and brain magnetic resonance imaging were unremarkable. Two days after vertigo onset, the patient developed a pulsatile headache that lasted for 24 h. The patient’s symptoms disappeared 4 days after vertigo onset. His left side canal paresis improved (21.0%). Follow-up vHITs were performed 4 days, 2 months, and 1 year later. The EAPD patterns gradually disappeared (Fig. 2 and video). There was no recurrence of headache or vertigo over the 1-year follow-up period. In our patient, the origin of EAPD pattern during vHIT for PC stimulation is difficult to establish. Considering that no similar artifacts have been reported [4] and that the same findings were observed in repeated tests, our findings are unlikely to be artifactual. A previous study reported this pattern in patients with nucleus prepositus hypoglossi lesions during stimulation of the anterior semicircular canal (AC) [3] and concluded it to be due to increased VOR gain resulting from the loss of ipsilateral AC inhibition from the flocculus, which preferentially inhibits AC pathways. However, Electronic supplementary material The online version of this article (https ://doi.org/10.1007/s0041 5-018-9088-0) contains supplementary material, which is available to authorized users.

The extent of vestibular impairment is important in recovery of canal paresis of patients with vestibular neuritis

OBJECTIVES We questioned whether the extent of vestibular impairment affected the recovery of vestibular function in acute vestibular neuritis (VN). The objective of this study was to identify how the extent of vestibular impairment influenced the recovery from canal paresis (CP) in patients with VN. METHODS We retrospectively reviewed the medical records of 46 patients diagnosed with acute vestibulopathy between January 2012 and December 2015. Pure-tone audiometry, a caloric test, and cervical vestibular evoked myogenic potential (cVEMP) testing were performed in all patients. Patients were divided into two groups, superior VN and total VN, according to the results of the cervical vestibular evoked myogenic potential (cVEMP) testing. The caloric test was rechecked 6-12months after diagnosis and the CP values were compared at 6 and 12months. The degree of recovery was evaluated by comparing the CP values. We defined good recovery as CP<25% at follow-up. RESULTS We found no significant difference in age, sex ratio, lesional site, or follow-up period between patients with superior VN and total VN. The follow-up CP in patients with superior VN was significantly lower than that in those with total VN. Twenty patients (65%) in the superior VN group exhibited good recovery as did three (20%) in the total VN group; the between-group difference was significant. CONCLUSIONS We found that CP values recovered well in patients with superior VN. We suggest that the extent of vestibular impairment is important in the recovery of CP in acute vestibulopathy.

Teaching Video NeuroImages: Upbeat and horizontal gaze-evoked nystagmus in bilateral medial medullary infarction

A 41-year-old man with progressive quadriparesis and generalized tingling sensation showed spontaneous upbeating nystagmus and horizontal gaze-evoked nystagmus (video at Neurology.org). The initial diffusion-weighted images showed an equivocal hyperintensity at midline of rostral medulla (upper row). Follow-up MRIs (lower row) showed characteristic heart appearance sign (figure).