Acute vestibular syndrome associated with anti-GQ1b antibody

Expanding Clinical Spectrum of Anti-GQ1b Antibody Syndrome: A Review

Importance

The discovery of the anti-GQ1b antibody has expanded the nosology of classic Miller Fisher syndrome to include Bickerstaff brainstem encephalitis, Guillain-Barré syndrome with ophthalmoplegia, and acute ophthalmoplegia without ataxia, which have been brought under the umbrella term anti-GQ1b antibody syndrome. It seems timely to define the phenotypes of anti-GQ1b antibody syndrome for the proper diagnosis of this syndrome with diverse clinical presentations. This review summarizes these syndromes and introduces recently identified subtypes.

Observations

Although ophthalmoplegia is a hallmark of anti-GQ1b antibody syndrome, recent studies have identified this antibody in patients with acute vestibular syndrome, optic neuropathy with disc swelling, and acute sensory ataxic neuropathy of atypical presentation. Ophthalmoplegia associated with anti-GQ1b antibody positivity is complete in more than half of the patients but may be monocular or comitant. The prognosis is mostly favorable; however, approximately 14% of patients experience relapse.

Conclusions and Relevance

Anti-GQ1b antibody syndrome may present diverse neurological manifestations, including ophthalmoplegia, ataxia, areflexia, central or peripheral vestibulopathy, and optic neuropathy. Understanding the wide clinical spectrum may aid in the differentiation and management of immune-mediated neuropathies with multiple presentations.

Clinical Features and Neurotologic Findings in Patients With Acute Unilateral Peripheral Vestibulopathy Associated With Antiganglioside Antibody

BACKGROUND AND OBJECTIVES

Anecdotal studies have reported the presence of antiganglioside antibodies in acute unilateral peripheral vestibulopathy (AUPV). This study aimed to determine the prevalence, clinical characteristics, and neurotologic findings of AUPV associated with antiganglioside antibodies.

METHODS

Serum antigangliosides were measured in consecutive patients with AUPV according to the Bárány Society criteria during the acute and recovery phases in a referral-based university hospital in South Korea from September 2019 to January 2023. Clinical characteristics and neurotologic findings were compared between those with and without antiganglioside antibodies. The results of video-oculography, video head impulse and bithermal caloric tests, and other neurotologic evaluations including ocular and cervical vestibular-evoked myogenic potentials and subjective visual vertical were compared between the 2. MRIs dedicated to the inner ear were also conducted when considered necessary.

RESULTS

One hundred five patients (mean age ± SD = 60 ± 13 years, 57 male) were included for analyses. During the acute phase, 12 patients (12/105, 11%) were tested positive for serum antiganglioside antibodies, including anti-GQ1b immunoglobulin (Ig) G (n = 5) or IgM (n = 4), anti-GM1 IgM (n = 3), and anti-GD1a IgG (n = 1, including 1 patient with a positive anti-GQ1b antibody). Patients with antiganglioside antibodies showed lesser intensity of spontaneous nystagmus (median [interquartile range] = 1.8 [1.2-2.1] vs 3.4 [1.5-9.5], p = 0.003) and a lesser degree of canal paresis (30 [17-47] vs 58 [34-79], p = 0.028) and gain asymmetry of the vestibulo-ocular reflex for the horizontal semicircular canal during head impulse tests (0.07 [-0.04 to 0.61] vs 0.36 [0.18-0.47], p = 0.032) than those without antibodies. Negative conversion of antibodies and vestibular recovery were observed in most patients (6/8, 75%). Among 30 patients with AUPV with 4-hour delayed 3D fluid-attenuated inversion recovery dedicated to the inner ear, gadolinium enhancement was observed in 18 (18/30, 60%), either in the vestibule (n = 9), semicircular canal (n = 6), or vestibular nerve (n = 5). The positivity rates based on specific antibodies could not be determined due to limited sample sizes.

DISCUSSION

The association between antiganglioside antibodies and AUPV suggests an immune-mediated mechanism in acute vestibular failure and extends the clinical spectrum of antiganglioside antibody syndrome.

Guillain-Barré Syndrome

OBJECTIVE

This article summarizes the clinical features, diagnostic criteria, differential diagnosis, pathogenesis, and prognosis of Guillain-Barré syndrome (GBS), with insights into the current and future diagnostic and therapeutic interventions for this neuromuscular syndrome.

LATEST DEVELOPMENTS

GBS is an acute, inflammatory, immune-mediated polyradiculoneuropathy that encompasses many clinical variants and divergent pathogenic mechanisms that lead to axonal, demyelinating, or mixed findings on electrodiagnostic studies. The type of antecedent infection, the development of pathogenic cross-reactive antibodies via molecular mimicry, and the location of the target gangliosides affect the subtype and severity of the illness. The data from the International GBS Outcome Study have highlighted regional variances, provided new and internationally validated prognosis tools that are beneficial for counseling, and introduced a platform for discussion of GBS-related open questions. New research has been undertaken, including research on novel diagnostic and therapeutic biomarkers, which may lead to new therapies.

ESSENTIAL POINTS

GBS is among the most frequent life-threatening neuromuscular emergencies in the world. At least 20% of patients with GBS have a poor prognosis and significant residual deficits despite receiving available treatments. Research is ongoing to further understand the pathogenesis of the disorder, find new biomarkers, and develop more effective and specific treatments.

Atypical anti-GQ1b antibody syndrome presenting with vomiting as the initial symptom: a case report and literature review

BACKGROUND

Anti-GQ1b antibody syndrome is a rare autoimmune neuropathy, and atypical cases are even more rare, only a few cases have been reported. Anti-GQ1b antibody syndrome is difficult in early diagnosis and prone to misdiagnosis. Generally,in children with anti-GQ1b antibody syndrome,extraocular muscle paralysis is the initial symptom. However, anti-GQ1b antibody syndrome with vomiting as the initial symptom followed by abnormal gait has not been reported.

CASE PRESENTATION

We reported a case of anti-GQ1b antibody syndrome with vomiting as the initial symptom, followed by abnormal gait. One day after vomiting, the child developed abnormal gait, which primarily manifested as a slight tilt of the upper body during walking as well as an opening and swaying of the legs at fast walking paces,then progressively aggravated, and finally he could not stand on his own.In the auxiliary examination, cerebrospinal fluid routine,biochemical and metagenomic Next-Generation Sequencing (DNA and RNA), brain + spinal cord contrast magnetic resonance imaging (MRI),magnetic Resonance angiography (MRA) and diffusion-weighted image (DWI), hip and knee joint ultrasound showed normal results. Anti-GQ1b antibody syndrome was not confirmed until the positive anti-GQ1b IgG antibody was detected in the serum. After treatment with intravenous immunoglobulin (IVIG) and glucocorticoid, the child recovered well, and a 3-month outpatient follow-up showed that the child was able to walk normally.

CONCLUSIONS

There are no previous reports of anti-GQ1b antibody syndrome with vomiting as the initial symptom, followed by abnormal gait. Therefore, this valuable case contributes to expanding the database of clinical manifestation of anti-GQ1b antibody syndrome, so as to improve pediatricians' awareness about such rare diseases and reduce misdiagnosis.

Acute comitant strabismus in anti-GQ1b antibody syndrome

Ophthalmoplegia is the diagnostic hallmark of anti-GQ1b antibody syndrome. This study aimed to define the patterns of acute comitant strabismus in patients with anti-GQ1b antibody syndromes. We retrospectively analyzed the ocular motor findings in 84 patients with anti-GQ1b antibody-associated ophthalmoplegia during the acute phases. Of the 84 patients, 11 (13%) showed acute comitant strabismus. Compared to those without, patients with acute comitant strabismus frequently showed abnormal ocular motor findings that included gaze-evoked (n = 8), spontaneous (n = 4) and positional nystagmus (n = 4), saccadic hypermetria (n = 3), head-shaking nystagmus (n = 2), pulse-step mismatch (n = 1), and impaired visual cancellation of the vestibulo-ocular reflex (n = 1, p < 0.001). On the contrary, iridoplegia (p = 0.029) and ptosis (p = 0.001) were more commonly observed in patients with paralytic (incomitant) strabismus than in those with acute comitant strabismus. Comitant strabismus can manifest during the acute phase of anti-GQ1b antibody syndromes in association with other central ocular motor abnormalities. These findings implicate that the cerebellum and/or brainstem can be the primary target of the anti-GQ1b antibodies.

Head shaking does not alter vestibulo ocular reflex gain in vestibular migraine

Vestibular Migraine (VM) is the most common cause of non-positional episodic vestibular symptoms. Patients with VM commonly report increased motion sensitivity, suggesting that vestibular responses to head movement may identify changes specific to VM patients. Here we explore whether the vestibulo-ocular reflex (VOR) gain alters in response to a clinical “headshake” maneuver in patients with VM. Thirty patients with VM in the inter-ictal phase, 16 patients with Benign Positional Paroxysmal Vertigo (BPPV) and 15 healthy controls were recruited. Patients responded to the question “Do you feel sick reading in the passenger seat of a car?” and completed a validated motion sickness questionnaire as a measure of motion sensitivity. Lateral canal vHIT testing was performed before and after headshaking; the change in VOR gain was calculated as the primary outcome. Baseline VOR gain was within normal limits across all participants. There was no significant change in VOR gain after headshaking in any group (p = 0.264). Patients were 4.3 times more likely to be in the VM group than in the BPPV group if they reported nausea when reading in the passenger seat of a car. We postulate that a headshake stimulus may be insufficient to disrupt cortical interactions and induce a change in VOR gain. Alternatively, changes in VOR gain may only be apparent in the acute phase of VM. Reading in the passenger seat of a car was considered uncomfortable in all VM patients suggesting that this specific question may be useful for the diagnosis of VM.

Current concepts in acute vestibular syndrome and video-oculography

PURPOSE OF REVIEW

We present here neuro-otological tests using portable video-oculography (VOG) and strategies assisting physicians in the process of decision making beyond the classical 'HINTS' testing battery at the bedside.

RECENT FINDINGS

Patients with acute vestibular syndrome (AVS) experience dizziness, gait unsteadiness and nausea/vomiting. A variety of causes can lead to this condition, including strokes. These patients cannot be adequately identified with the conventional approach by stratifying based on risk factors and symptom type. In addition to bedside methods such as HINTS and HINTS plus, quantitative methods for recording eye movements using VOG can augment the ability to diagnose and localize the lesion. In particular, the ability to identify and quantify the head impulse test (VOR gain, saccade metrics), nystagmus characteristics (waveform, beating direction and intensity), skew deviation, audiometry and lateropulsion expands our diagnostic capabilities. In addition to telemedicine, algorithms and artificial intelligence can be used to support emergency physicians and nonexperts in the future.

SUMMARY

VOG, telemedicine and artificial intelligence may assist physicians in the diagnostic process of AVS patients.

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.

Graves' disease with anti-GQ1b antibody syndrome: a rare case report

BACKGROUND

Graves' disease and anti-GQ1b antibody syndrome are both autoimmune diseases, and there have been few reports on whether there is a correlation between the two. In this study, we present the case of a woman who was diagnosed with Graves' disease and anti-GQ1b antibody syndrome in succession.

CASE PRESENTATION

The chief complaints of this patient were limb weakness and blurred vision. Graves' disease was diagnosed by examination of thyroid function and thyroid autoantibodies, but the clinical symptoms were not relieved after antihyperthyroidism treatment. Finally, it was found that Graves' disease was complicated by anti-GQ1b antibody syndrome, and the symptoms were relieved after treatment with glucocorticoids and intravenous immunoglobulin. We also explored the possible mechanism of these diseases through a literature review.

CONCLUSIONS

We report a rare case of the cooccurrence of Graves' disease and anti-GQ1b antibody syndrome. Immune dysregulation might be the pathogenesis of the association, but there is no precise supporting evidence, and more research is needed.

Acute Vestibular Syndrome

PURPOSE OF REVIEW

This article provides a practical approach to acute vestibular syndrome while highlighting recent research advances.

RECENT FINDINGS

Acute vestibular syndrome is defined as sudden-onset, continuous vertigo lasting longer than 24 hours with associated nausea and vomiting, all of which are worsened with head movement. Acute vestibular syndrome is provoked by a variety of central and peripheral causes, the most common of which are vestibular neuritis and acute stroke (posterior circulation). A clinical approach focusing on timing, associated history, and ocular motor findings can improve diagnostic accuracy and is more sensitive and specific than early neuroimaging. Because of the shared neurovascular supply, both peripheral and central vestibular disorders can manifest overlapping signs previously considered solely peripheral or central, including vertical skew, nystagmus, abnormal vestibular ocular reflex, hearing loss, and gait instability. Although acute vestibular syndrome is typically benign, stroke should be considered in every person with acute vestibular syndrome because it can act as a harbinger of stroke or impending cerebellar herniation. Treatment is focused on physical therapy because the evidence is minimal for the long-term use of medication.

SUMMARY

The diagnosis of acute vestibular syndrome first requires the elimination of common medical causes for dizziness. Next, underlying pathology must be determined by distinguishing between the most common causes of acute vestibular syndrome: central and peripheral vestibular disorders. Central vestibular disorders are most often the result of ischemic stroke affecting the cerebellar arteries. Peripheral vestibular disorders are assumed to be caused mostly by inflammatory sources, but ischemia of the peripheral vestibular apparatus may be underappreciated. By using the HINTS Plus (Head Impulse test, Nystagmus, Test of Skew with Plus referring to hearing loss assessment) examination in addition to a comprehensive neurologic examination, strokes are unlikely to be missed. For nearly all acute vestibular disorders, vestibular physical therapy contributes to recovery.

Clinical Characterization of Anti-GQ1b Antibody Syndrome in Childhood

Objective: To delineate the comprehensive clinical features of anti-GQ1b antibody syndrome in childhood. Methods: The clinical data of children diagnosed with anti-GQ1b antibody syndrome at two Chinese tertiary pediatric neurology centers were collected and analyzed. We also conducted a systematic literature review on anti-GQ1b antibody syndrome in children. Results: This study included 78 children with anti-GQ1b antibody syndrome, consisting of 12 previously unreported cases from the two Chinese centers. The median onset age was 10 years (range, 2-18 years). The most common phenotype was acute ophthalmoparesis (32%), followed by classic Miller Fisher syndrome (15%), and Bickerstaff brainstem encephalitis (12%). External ophthalmoplegia (48%), sensory disturbance (9%), and bulbar palsy (9%) were the three most frequent onset symptom manifestations. Brain or spinal lesions on MRI and abnormal recordings by nerve conduction study were present in 18% (12/68) and 60% (27/45) of cases, respectively. There was CSF albuminocytologic dissociation in 34% of the patients (23/68). IV immunoglobulin alone or combined with steroids or plasma exchange was administered to 58% of patients (42/72). We did not find a significant correlation between early improvement up to 3 months and age onset and phenotype. All patients showed different degrees of recovery, and 81% (57/70) had complete recovery within 1 year. Conclusions: Acute ophthalmoparesis and classic Miller Fisher syndrome are the most common phenotypes of anti-GQ1b antibody syndrome in childhood. The majority of patients show good response to immunotherapy and have favorable prognosis.

Update on Nystagmus and Other Ocular Oscillations

This review reports on recent advances in understanding nystagmus and other involuntary eye movements. Advances in quantitative evaluations of eye movements using oculography, computational model simulations, genetics, and imaging technologies have markedly improved our understanding of the pathophysiology of involuntary eye movements, as well as their diagnosis and management. Patient-initiated capture of eye movements, especially when paroxysmal, and the online transfer of these data to clinicians would further enhance the ability to diagnose involuntary eye movements.