Persistent Nystagmus in Chronic Phase of Lateral Medullary Infarction.

BACKGROUND AND PURPOSE: We aimed to determine the patterns and mechanisms of persistent nystagmus (PN) lasting >1 year in lateral medullary infarction (LMI). METHODS: We recruited 13 patients with PN due to LMI and another 13 with transient nystagmus (TN) (<1 year) as control. All patients underwent oculography, rotatory chair test, caloric test, bedside head impulse test, dizziness handicap inventory (DHI), and brain MRI. RESULTS: All patients had spontaneous, contralesional, horizontal-torsional nystagmus during the acute phase. Although two patients exhibited consistent contralesional torsional nystagmus, most patients (11/13, 85%) with PN evolved from the initial contralesional to ipsilesional nystagmus. During horizontal gaze, the patterns of ipsilesional PN were diverse; torsional (n=5), torsional-downbeat (n=2), horizontal (n=2), and horizontal nystagmus while looking at the lesion side, and torsional nystagmus while looking at the opposite side (n=2). During rotatory chair test, the gains of the vestibulo-ocular reflex in the PN group were lower than those in the TN group to the lesion side at 0.02 and 0.64 Hz. The caudal and ventrolateral parts of the vestibular nuclei were mostly involved in patients with PN. The DHI score did not differ between the groups. CONCLUSIONS: PN patterns frequently change in LMI. Resultant vestibular asymmetry after vestibular afferents or cerebellar inhibitory pathway damage and/or inappropriate vestibular compensation may be responsible for PN in LMI. Impairment of the horizontal or vertical neural integrators may be another cause. The presence of PN does not necessarily indicate more severe dizziness in LMI.

Acute vestibular asymmetry disorder: a new disease entity in acute vestibular syndrome?

BACKGROUND: Acute vestibular syndrome (AVS) is characterized by the rapid onset of vertigo, nausea, vomiting and gait unsteadiness, which lasts for days. AIMS/OBJECTIVES: We report cases as acute vestibular asymmetry disorder (AVAD), with presentations that mimic vestibular neuritis (VN) but without central lesions. MATERIALS AND METHODS: We retrospectively reviewed records of patients presenting with acute spontaneous vertigo lasting more than 24 h from January 2011 to June 2016. Among 341 patients, five showed different findings that did not indicate either VN or stroke. We analyzed the clinical features and vestibular assessments of these patients. RESULTS: All five patients showed spontaneous nystagmus continuing for several days. However, head impulse tests (HITs) did not reveal a corrective saccade. Brain magnetic resonance imaging showed no abnormal lesions. The bithermal caloric test revealed directional preponderance without canal paresis. Finally, the slow harmonic test of the rotatory chair revealed unilateral high gain and phase within the normal range, but a significantly asymmetric response was observed. No patients showed recurrence during follow-up. CONCLUSIONS AND SIGNIFICANCE: Our study suggests that a normal HIT in AVS is not always a dangerous sign indicating an acute stroke. From our observations, we propose that AVAD would be a new disease entity within AVS.

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.

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.

Abnormality of cervical vestibular-evoked myogenic potentials and ocular vestibular-evoked myogenic potentials in patients with recurrent benign paroxysmal postitional vertigo.

CONCLUSION: Our results show that cervical vestibular-evoked myogenic potential (cVEMP) or ocular VEMP (oVEMP) abnormalities in the recurrent benign paroxysmal positional vertigo (BPPV) group were significantly higher than those in the non-recurrent BPPV group. Therefore, we can infer that VEMP abnormality is one of risk factors for BPPV recurrence. OBJECTIVE: This prospective study aimed to test the hypothesis that otolith dysfunction using the VEMP test is a cause of recurrence of BPPV. METHODS: cVEMP and oVEMP tests using 500 Hz tone-burst stimuli were performed on 16 patients with recurrent BPPV between March 2010 and December 2011. Both VEMP tests were performed in 20 patients with non-recurrent BPPV. RESULTS: The differences in age, sex, and involved canal between the recurrent and non-recurrent BPPV groups were not significant. Abnormal cVEMP responses were detected in 5 of 16 (31.3%) subjects in the recurrent BPPV group and abnormal oVMEP responses were detected in 4 of 16 (25%) subjects in the recurrent BPPV group. When we defined VEMP abnormality as an abnormal cVEMP or abnormal oVEMP, VEMP abnormalities were detected in eight (50%) subjects in the recurrent BPPV group and in three (15%) subjects in the non-recurrent BPPV group; the difference between groups was significant.

Otolith function in patients with head trauma.

This study evaluates the otolith function of patients with head trauma, postulating that otolith dysfunction is a cause of nonspecific dizziness after head trauma. We prospectively enrolled 28 patients referred within 3 months after head trauma between March 2007 and December 2009. Pure tone audiometry, caloric testing and otolith function tests, including cervical vestibular evoked myogenic potential (cVEMP) and subjective visual vertical (SVV) tests, were performed on all patients. The relationship between otolith function and otologic symptoms was analyzed. Of the 28 patients with head trauma, 18 complained of dizziness and 12 experienced hearing loss, including 6 patients who complained of both. On defining otolith dysfunction as an abnormal cVEMP or abnormal SVV, a significant difference in otolith dysfunction existed between the groups with and without dizziness [72 (13/18) vs. 20% (2/10)]. In contrast, no significant difference in otolith dysfunction was detected between the abnormal and normal hearing groups. A significant number of the patients who complained of nonspecific dizziness after trauma had abnormal otolith function. After trauma, when patients complain of dizziness, vestibular function tests, including otolith function tests, should be considered.

A case of paramyotonia congenita without periodic paralysis: electrophysiological and molecular genetic studies.

Paramyotonia congenita (PC), first described in 1886 by Eulenberg, is characterized by cold and exercise-induced muscle stiffness and intermittent flaccid paresis not necessarily related to cold or myotonia. Several authors segregated a pure form of PC, which has no periodic paralysis, even after cold exposure. The existence of this phenotype has been debated in the literature. We describe electrophysiological and molecular genetic features of a patient with PC who had no history of periodic paralysis. Immersion in cold water or potassium load could not induce clinical paralysis. However, repetitive nerve stimulation and exercise test demonstrated a drop in compound muscle action potential amplitude. Genetic analysis revealed the substitution of valine for glycine on the human skeletal muscle sodium channel (SCN4A) gene. The G1306V mutation is rare in the classic form of PC, and moreover might be the first in pure paramyotonia.

Association of polymorphisms in thromboxane A2 receptor and thromboxane A synthase 1 with cerebral infarction in a Korean population.

Thromboxane A2 (TBXA2) is a potent vasoconstrictor in cerebral circulation and is a known contributor to the pathogenesis of cerebral infarction. Thromboxane A2 synthase 1 (TBXAS1) and thromboxane A2 receptors (TBXA2R) are key components in TBXA2 function. We examined whether genetic variants in TBXA2R and TBXAS1 are risk factors for cerebral infarction by genotyping 453 Korean patients with noncardiogenic cerebral infarction and 260 controls. A few, specific polymorphisms in the TBXA2R (-3372G>C, +4710T>C and 4839T>C) and TBXAS1 (+16184G>T, +141931A>T and +177729G>A) genes were chosen and investigated. Logistic regression showed the frequencies of TBXAS1+16184G>T and TBXAS1- ht3 were significantly more frequent in cerebral infarction (P=0.002, OR=2.75 and P=0.01, OR=1.57, respectively), specifically in small-artery occlusion (SAO) type of cerebral infarction (P=0.0003 and 0.005, respectively). These results suggest specific TBXAS1 gene polymorphisms may be a useful marker for development of cerebral infarction, especially SAO type in Korean population.

Analysis of the lesion distributions and mechanism of acute middle cerebral artery infarctions involving the striatocapsular region.

BACKGROUND AND PURPOSE: There is no clear description about the patterns of each mechanism of striatocapsular infarctions. The aims of our study were to elucidate differences in the distributions of lesions of acute middle cerebral artery (MCA) infarctions involving the striatocapsular region and to compare those following embolic striatocapsular infarctions with those originating from MCA disease. METHODS: We prospectively enrolled patients with acute infarcts located in the lenticulostriate artery territory that were not lacunar infarcts. Brain coronal diffusion-weighted imaging (DWI) was obtained and magnetic resonance angiography (MRA) was carried out to evaluate the distribution of infarct lesions and MCA stenosis in all patients. The types of infarct distribution were divided into three categories: (1) dominant in the distal territory (DD), (2) distributed equally between the distal and proximal territories (DE), and (3) dominant in the proximal territory. We performed tests for embolic sources (transthoracic echocardiography, transesophageal echocardiography, Holter monitoring, and contrast-enhanced MRA including the aortic arch) in most patients. Stroke mechanisms were classified into stroke from proximal embolism, MCA disease, and stroke of undetermined etiology. RESULTS: A total of 47 patients (28 men and 19 women; mean age, 62 years) were recruited. A proximal embolic source was significantly more prevalent in patients with a DE lesion than in those with a DD lesion. The most common proximal embolic source was of cardiac origin. In contrast, symptomatic MCA stenoses were more common in patients with a DD lesion than in those with a DE lesion. CONCLUSIONS: These results suggest that the dominant area of striatocapsular infarction on coronal DWI is an important clue for stroke etiology. Coronal DWI could therefore be helpful to determining the mechanisms in patients with striatocapsular infarctions that are currently described as having an "undetermined etiology" according to the Trial of Org 10172 in Acute Stroke Treatment classification.

Extensive brain stem lesions in thrombotic thrombocytopenic purpura: repeat magnetic resonance findings.

The authors report on an unusual case of extensive brain stem lesions as a manifestation of thrombotic thrombocytopenic purpura (TTP). A 28-year-old woman developed rapidly progressive neurologic deficits 5 days after a cesarean delivery. Her condition had been normal after delivery. Initial magnetic resonance imaging (MRI) revealed extensive T2 hyperintense lesions involving the entire brain stem; only part of the pons showed hyperintense abnormalities in a concomitantly taken diffusion-weighted image. The hematologic evaluations and her clinical course revealed the diagnosis of TTP, so plasma exchange and methyl-prednisolone therapy were initiated. After 10 days of treatment, she developed neurologic improvement. A follow-up MRI on the 75th day revealed dramatically reduced brain stem lesions with only residual punctate lesions in the pons. Her remaining neurologic deficits were dysarthria, limb ataxia, and left hemiparesis. As demonstrated in this study, extensive brain stem involvement should be added as a possible neuroimaging feature of TTP.

Isolated superior rectus palsy due to contralateral midbrain infarction.

BACKGROUND: Isolated superior rectus palsy due to a contralateral midbrain lesion has not been reported. CASE DESCRIPTION: A 71-year-old woman suddenly developed diplopia. Examination showed that she had isolated superior rectus paresis. Magnetic resonance imaging showed a tiny infarct at the area of the oculomotor nucleus on the contralateral side. CONCLUSION: Isolated superior rectus palsy may be caused by a contralateral midbrain lesion that selectively involves crossing superior rectus nerve fibers.

Neuro-Behçet's disease mimicking a cerebral tumor: a case report.

We report a rare case of neuro-Behcet's disease (NBD) presenting as an inflammatory pseudotumor in the brain. A 52-year-old woman was evaluated for subacute dizziness and headache. Brain magnetic resonance (MR) imaging showed a right cerebellar mass, which disappeared 2 weeks later. After a year, recurrent mucocutaneous manifestations of Beh et's disease were observed. Immunosuppressant and steroid maintenance treatment were started. She experienced two more neurologic attacks and brain MR imaging revealed an enhancing mass in the right temporal lobe. The second attack showed a good response to steroid pulse therapy, but the third attack did not respond to steroid and her neurologic signs suggested an impending transtentorial hernia. The right temporal lobectomy was performed for the purpose of life-saving. The pathologic finding of the mass was a chronic inflammatory vasculitis, compatible with NBD.