Ocular lateropulsion in Wallenberg syndrome

Diagnosing and localizing the acute vestibular syndrome - Beyond the HINTS exam

When assessing the acutely dizzy patient, the HINTS 'Plus' (Head Impulse, Nystagmus, Test of Skew, 'Plus' a bedside assessment of auditory function) exam is a crucial component of the bedside exam. However, there are additional ocular motor findings that can help the clinician distinguish peripheral from central etiologies and enable accurate localization, especially when the patient has acute dizziness, vertigo and/or imbalance but without spontaneous nystagmus. We will review the literature on these findings which are 'beyond HINTS' and include saccades/ocular lateropulsion, smooth pursuit, and provocative maneuvers including head-shaking and positional testing (not part of the HINTS exam). Additionally, we will expound on the localizing value of nystagmus, ocular alignment and the ocular tilt reaction (parts of the HINTS exam). The paper has been organized neuroanatomically, based on brainstem and cerebellar structures that have been reported to cause the acute vestibular syndrome.

Ocular contrapulsion followed by ipsipulsion in Wallenberg syndrome: The first case report in literature

Wallenberg syndrome is also called lateral medullary syndrome, a neurological disorder resulting from occlusion of the vertebral artery or the posterior inferior cerebellar artery. The clinical presentations are associated with a variety of indications, including vestibulocerebellar symptoms, autonomic dysfunction and ipsilateral cerebellar signs. The ipsipulsion, an abnormality of the ocular movement associated with the Wallenberg syndrome, is more specific to the lateral medullary syndrome and is characterized by a tonic deviation of the eyes in the direction of the damaged side, more prominently when the visual fixation is interrupted. A 51-year-old male patient presented with a sudden permanent rotatory dizziness, unsteady gait, numbness in the left hemibody, left palate paresis, incoordination on left side and horizontal jerk nystagmus with left fast fase. Magnetic resonance imaging showed infarction in the left medulla and cerebellar. The ocular exam revealed saccadic lateropulsion ipsilateral to lesion. In the neurologic evaluation of the patient with Wallenberg syndrome, numerous abnormalities manifestations are present, such as vestibulo-ocular reflex deficiency, saccadic abnormalities, low pursuance movements and gaze fixation, and eye alignment dysfunction. This semiologic feature had not been described in literature until now. We hypothesize that an initial vasogenic edema extending to the left medial medulla following the acute stroke could explain the early presentation with saccadic counterpulsion. After one week and regression of the edema, the finding of lateropulsion has alternated to the classic ipsipulsion related to Wallenberg syndrome. The following case report depicts a rare case of Wallenberg syndrome associated with alterations of the ocular motricity.

Central Ocular Motor Disorders: Clinical and Topographic Anatomical Diagnosis, Syndromes and Underlying Diseases

The key to the diagnosis of ocular motor disorders is a systematic clinical examination of the different types of eye movements, including eye position, spontaneous nystagmus, range of eye movements, smooth pursuit, saccades, gaze-holding function, vergence, optokinetic nystagmus, as well as testing of the function of the vestibulo-ocular reflex (VOR) and visual fixation suppression of the VOR. This is like a window which allows you to look into the brain stem and cerebellum even if imaging is normal. Relevant anatomical structures are the midbrain, pons, medulla, cerebellum and rarely the cortex. There is a simple clinical rule: vertical and torsional eye movements are generated in the midbrain, horizontal eye movements in the pons. For example, isolated dysfunction of vertical eye movements is due to a midbrain lesion affecting the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), with impaired vertical saccades only or vertical gaze-evoked nystagmus due to dysfunction of the Interstitial nucleus of Cajal (INC). Lesions of the lateral medulla oblongata (Wallenberg syndrome) lead to typical findings: ocular tilt reaction, central fixation nystagmus and dysmetric saccades. The cerebellum is relevant for almost all types of eye movements; typical pathological findings are saccadic smooth pursuit, gaze-evoked nystagmus or dysmetric saccades. The time course of the development of symptoms and signs is important for the diagnosis of underlying diseases: acute: most likely stroke; subacute: inflammatory diseases, metabolic diseases like thiamine deficiencies; chronic progressive: inherited diseases like Niemann-Pick type C with typically initially vertical and then horizontal saccade palsy or degenerative diseases like progressive supranuclear palsy. Treatment depends on the underlying disease. In this article, we deal with central ocular motor disorders. In a second article, we focus on clinically relevant types of nystagmus such as downbeat, upbeat, fixation pendular, gaze-evoked, infantile or periodic alternating nystagmus. Therefore, these types of nystagmus will not be described here in detail.

Crossed brainstem syndrome revealing bleeding brainstem cavernous malformation: an illustrative case

BACKGROUND

Since the nineteenth century, a great variety of crossed brainstem syndromes (CBS) have been described in the medical literature. A CBS typically combines ipsilateral cranial nerves deficits to contralateral long tracts involvement such as hemiparesis or hemianesthesia. Classical CBS seem in fact not to be so clear-cut entities with up to 20% of patients showing different or unnamed combinations of crossed symptoms. In terms of etiologies, acute brainstem infarction predominates but CBS secondary to hemorrhage, neoplasm, abscess, and demyelination have been described. The aim of this study was to assess the proportion of CBS caused by a bleeding episode arising from a brainstem cavernous malformation (BCM) reported in the literature.

CASE PRESENTATION

We present the case of a typical Foville syndrome in a 65-year-old man that was caused by a pontine BCM with extralesional bleeding. Following the first bleeding episode, a conservative management was decided but the patient had eventually to be operated on soon after the second bleeding event.

DISCUSSION

A literature review was conducted focusing on the five most common CBS (Benedikt, Weber, Foville, Millard-Gubler, Wallenberg) on Medline database from inception to 2020. According to the literature, hemorrhagic BCM account for approximately 7 % of CBS. Microsurgical excision may be indicated after the second bleeding episode but needs to be carefully weighted up against the risks of the surgical procedure and openly discussed with the patient.

CONCLUSIONS

In the setting of a CBS, neuroimaging work-up may not infrequently reveal a BCM requiring complex multidisciplinary team management including neurosurgical advice.

Radiographic horizontal gaze deviation in the setting of acute PICA territory ischemia: A potential mimic of large vessel occlusion

PURPOSE

Horizontal gaze deviation (HGD) is a predictor of acute large vessel occlusion (LVO) and helps to expedite the triage of patients to CTA and endovascular-capable sites. Patients with acute cerebellar ischemia, particularly involving the PICA territory, can also exhibit HGD.

MATERIALS AND METHODS

We reviewed 2260 CTA stroke assessment cases between January 2016 and May 2020. Forty-six patients with CTA-proven acute PICA occlusions were identified and compared with 114 patients with acute LVO (ICA, M1, and M1/2). Both clinical and radiographic HGD were examined. The degree of radiographic HGD was measured for each patient. Site of ischemia was confirmed on subsequent MRI.

RESULTS

Of the 46 patients with acute PICA occlusions, 20 (43.5%) patients had radiographic (+) HGD with either ipsilateral or contralateral gaze deviation, 6 of whom (13.0%) displayed clinical HGD. Of the 114 patients with LVO (control group), 72 (63.2%) patients had radiographic (+) HGD, all ipsilateral, 49 of whom (68.0%) displayed clinical HGD. The mean degree of HGD between PICA and LVO were 30.0° vs. 22.9°, respectively, p < 0.001; AUC = 0.68.

CONCLUSION

Patients with acute PICA occlusion can exhibit either ipsilateral or contralateral HGD and a higher degree of HGD than LVO occlusion on NECT. In hyperacute stroke, the presence of radiographic HGD > 30° in the absence of ischemic changes in the MCA territory should prompt clinicians to closely evaluate for features of early ischemic changes in the cerebellar hemispheres that suggest acute PICA occlusion.

Conjugate Eye Deviation in Unilateral Lateral Medullary Infarction

Background and Purpose

The initial diagnosis of medullary infarction can be challenging since CT and even MRI results in the very acute phase are often negative.

Methods

A retrospective, observer-blinded study of horizontal conjugate eye deviation was performed in 1) 50 consecutive patients [age 58±15 years (mean±SD), 74% male, National Institutes of Health Stroke Scale 2±1] with acute unilateral lateral medullary infarction as seen in MRI (infarction group), 2) 54 patients with transient brainstem symptoms [transient ischemic attack of brainstem (TIA) group; age 69±16 years, 59% male], and 3) 53 patients (age 59±20 years, 49% male) with diagnoses other than stroke (control group).

Results

Conjugate eye deviation was found in all patients in the infarction group [n=47 (94%) with ipsilesional deviation and n=3 (6%) with contralesional deviation] compared to 41% (n=22) in the brainstem TIA group and 15% (n=8) in the control group (p<0.0001). Within all groups mean deviation and range were similar for both sides (to the right vs. to the left side 26.6°±12.3 vs. 26.1°±12.3 in the infarction group, 10.5°±5.8 vs. 8.4°±6.3 in the brainstem TIA group and 4.5°±3.2 vs. 7.5°±3.2 in the control group). The extent of eye deviation was significantly greater in the infarction group (p<0.05).

Conclusions

All patients with MRI-demonstrated unilateral medullary infarction showed conjugate eye deviation. Therefore, conjugate eye deviation in patients with suspected acute lateral medullary infarction is a helpful sensitive sign for supporting the diagnosis, particularly if the deviation is >20°.

Contralesional spasticity of conjugate gaze in striatocapsular infarction

A 44-year-old man developed sudden non-fluent aphasia and right hemiplegia due to left striatocapsular infarction (Figure). Neurologic examination revealed gaze deviation to the right with eyes closed, but not with eyes open (Video). There was no spontaneous or gaze-evoked nystagmus, even after elimination of visual fixation. Leftward pursuit was impaired in a craniotopic frame of reference, and horizontal saccades were hypometric in both directions. Head impulse test was normal in the horizontal plane and there were no visual field defects. The contralesional gaze deviation with eye closure persisted for ten days.