A case of apogeotropic nystagmus with brainstem lesion: An implication for mechanism of central apogeotropic nystagmus

Central positional nystagmus: an update

Clinically, central positional nystagmus (CPN) is often suspected when atypical forms of its peripheral counterpart, i.e., benign paroxysmal positional vertigo (BPPV), are observed, namely a linear horizontal nystagmus as in horizontal canal BPPV or a downwardly and torsionally beating nystagmus as in anterior canal BPPV. Pathophysiologically, CPN is caused by cerebellar and/or brainstem dysfunction. Recent work has provided further insights into the different clinical phenotypes and the underlying pathomechanisms. We performed a PubMed review focused on the findings on CPN using the key words "Central Positional Nystagmus", "Central Positional Vertigo", "Positional Nystagmus" OR "Positioning Nystagmus" OR "Positional Vertigo" OR "Positioning Vertigo" AND "Central" from January 2015 to August 2021. CPN may account for up to 12% of patients with positional nystagmus. Clinical data on CPN are mostly based on case reports or small retrospective case series. CPN is frequently associated with cerebellar and/or brainstem structural lesions, namely stroke, tumours or demyelination, or diffuse involvement of these structures due to degenerative or autoimmune/paraneoplastic diseases; it is also found in patients with vestibular migraine. CPN can be paroxysmal or persistent. The direction of the nystagmus is often downward in head-hanging or apogeotropic in lateral supine positions; combinations of both forms also occur. Clinically it is important to note that CPN is often associated with other central, often cerebellar ocular motor or other neurological signs; typically, it is not improved by the therapeutic liberatory manoeuvres for BPPV. These additional features are also important for the diagnosis, in particular if no structural lesions are found. Pathophysiologically, CPN is believed to reflect an abnormal integration of semicircular canal-related signals by the cerebellar nodulus, uvula and/or tonsil, ultimately providing an erroneous estimation of the head tilt and/or eye position coordinates. The natural course of CPN remains, so far, largely unknown. Symptomatic treatment of CPN consists of pharmacotherapy, e.g., with 4-aminopyridine, and causative treatment of the underlying disease if known. CPN is an important differential diagnosis to BPPV and a clinically relevant entity with heterogenous clinical presentations and various pathomechanisms and etiologies. In particular, studies on the natural course and treatment of CPN are needed.

Central Positional Nystagmus: A Systematic Literature Review

Objective

To provide a systematic review of the clinical and radiological features of lesion-induced central positional nystagmus (CPN) and identify salient characteristics that differentiate central from peripheral positional nystagmus (PN).

Methods

Systematic literature search according to the preferred reporting items for systematic reviews and meta-analysis.

Results

A total of 82 patients from 28 studies met the participants intervention, comparison, outcomes, and study designs criteria for inclusion. An atypical direction of nystagmus for the stimulated canal was reported in 97.5% patients during Dix–Hallpike (D–H) and 54.5% upon supine roll testing. Five types of CPNs were identified during positional testing: positional horizontal nystagmus (pHN) (36.8%), positional downbeating nystagmus (pDBN) (29.2%), positional torsional nystagmus (pTN) (2.1%), positional upbeating nystagmus (pUBN) (2.1%), and a combination of the four profiles (29.9%). CPN was paroxysmal (<60 s) in 85% patients on straight head hanging (SHH), 63.9% on D–H, and 37.5% on supine roll, and had a latency <3 s upon positioning in 94.7% patients in which it was reported. Concurrent vertigo was reportedly present in 63.4% patients and 48.8% demonstrated other neurological signs. Radiologically, in 74.4%, there was mention of cerebellar involvement, isolated brainstem involvement in 8.5%, and 14.6% involved the fourth ventricle.

Conclusion

Currently, there is a lack of robust data on the clinical and radiological characteristics of CPN highlighting the need for better phenotyping of CPN to help differentiate this entity from peripheral causes of PN. With increased awareness of CPN, particularly in the acute setting, we may see a change in the estimated prevalence of CPN and improved clinical markers to promptly identify the frequently sinister underlying causes.

Vertigo in brainstem and cerebellar strokes

PURPOSE OF REVIEW

The aim of this study is to review the recent findings on the prevalence, clinical features, and diagnosis of vertigo from brainstem and cerebellar strokes.

RECENT FINDINGS

Patients with isolated vertigo are at higher risk for stroke than the general population. Strokes involving the brainstem and cerebellum may manifest as acute vestibular syndrome, and acute isolated audiovestibular loss may herald impending infarction in the territory of the anterior inferior cerebellar artery. Appropriate bedside evaluation is superior to MRI for detecting central vestibular syndromes. Recording of vestibular-evoked myogenic potentials is useful for evaluation of the central otolithic pathways in brainstem and cerebellar strokes.

SUMMARY

Accurate identification of isolated vascular vertigo is very important since misdiagnosis of acute stroke may result in significant morbidity and mortality, whereas overdiagnosis of vascular vertigo would lead to unnecessary costly work-ups and medication.

Analysis of benign paroxysmal positional nystagmus in children

INTRODUCTION

Benign paroxysmal positional vertigo (BPPV) is the most common vestibular disorder. However, BPPV in children has been studied less extensively than in the adult population. This is because the observation of benign paroxysmal positional nystagmus (BPPN) in children is technically very difficult and BPPV is rare in children. In this study, we present the only two cases of BPPV in children in which we successfully recorded and analyzed the BPPN.

METHODS

One case was an 11-year-old boy and the other was a 3-year-old girl. We analyzed their BPPN three-dimensionally.

RESULTS

Apogeotropic positional nystagmus was observed in the first case. We analyzed it to verify the presence of cupulolithiasis in the horizontal semicircular canal (HSCC). Geotropic positional nystagmus was observed in the second case, and the analyzed data indicated the presence of canalolithiasis in HSCC. Over the last decade, we have examined 3341 patients complaining of vertigo or dizziness. Among them, there were 63 children with the same complaint, so that the proportion of cases of BPPV in children was only 3% (2/63).

DISCUSSION

Among patients complaining of vertigo or dizziness, children with BPPV are rare (3%). However, we have recorded their BPPN to confirm that BPPV does occur in children and that their characteristics of positional nystagmus are generally identical to those in adults. We emphasize that this is the first report of a child as young as 3 years old being diagnosed with BPPV.