Periodic downbeat nystagmus

Downbeat nystagmus: a clinical and pathophysiological review

Downbeat nystagmus (DBN) is a neuro-otological finding frequently encountered by clinicians dealing with patients with vertigo. Since DBN is a finding that should be understood because of central vestibular dysfunction, it is necessary to know how to frame it promptly to suggest the correct diagnostic-therapeutic pathway to the patient. As knowledge of its pathophysiology has progressed, the importance of this clinical sign has been increasingly understood. At the same time, clinical diagnostic knowledge has increased, and it has been recognized that this sign may occur sporadically or in association with others within defined clinical syndromes. Thus, in many cases, different therapeutic solutions have become possible. In our work, we have attempted to systematize current knowledge about the origin of this finding, the clinical presentation and current treatment options, to provide an overview that can be used at different levels, from the general practitioner to the specialist neurologist or neurotologist.

An atypical case of hypomagnesemia-induced cerebellar syndrome with literature review

Cerebellar ataxia in adults is always a diagnostic challenge. One of the important causes of late-onset cerebellar ataxia is hypomagnesemia. Hypomagnesemia can have varied manifestations and is attributable to numerous causes. Identification of hypomagnesemia-induced cerebellar syndrome (HiCS) is important as it is reversible but often missed. HiCS has distinct clinical findings and characteristic magnetic resonance imaging (MRI) findings. HiCS presents with distinct clinical, biochemical, and neuroimaging findings, but it cannot be ruled out even in the absence of neuroimaging findings. This condition has to be treated promptly and meticulously to avoid precipitating any serious complications, and a strong suspicion is required for the diagnosis. The underlying cause should be evaluated and managed, as HiCS is a serious but potentially reversible disease with a good prognosis. We present a case of HiCS presenting with a characteristic history of recurrent ataxia, tremor, and vertigo that improved with treatment. Our patient was atypical, as there were no significant MRI findings attributable to hypomagnesemia. Only seven case reports are available throughout the world that show such disparity.

Movement Disorders and Other Neurologic Impairment Associated With Hypomagnesemia: A Systematic Review

Purpose of Review

The objective of this study was to explore the clinical spectrum of movement disorders and associated neurologic findings in hypomagnesemia and challenges in diagnosis and treatment.

Recent Findings

Sixty patients were identified in the literature for analysis. Movement disorders observed were postural tremor (23.3%, n = 14), resting tremor (8.3%, n = 5), intention tremor (10%, n = 6), ataxia involving the trunk (48.3%, n = 29) or limbs (25%, n = 15) and dysarthria (21.7%, n = 13), athetosis (8.3%, n = 5), myoclonus (6.7%, n = 4), and chorea (1.8%, n = 1). Symptoms may be accompanied by downbeat nystagmus, tetany, drowsiness, vertigo, and proximal muscle weakness. Residual deficits were noted in 16 (26.67%) patients. Serum magnesium was 1.3 mg/dL or lower in 53 patients (88.3%). Imaging findings include bilateral cerebellar (20%, n = 11) and vermis hyperintensities (9.09%, n = 5) and normal imaging. Proton pump inhibitors are the commonest etiology.

Summary

The movement disorders linked with hypomagnesemia can be associated with varied neurologic symptoms. A high degree of suspicion will enable early diagnosis to prevent residual deficits.

Cerebellar Syndrome Induced by Hypomagnesemia: A Treatable Cause of Ataxia Not to be Missed. Report of Three Cases and a Review of the Literature

Background

Magnesium is an important intracellular cation involved in essential enzymatic reactions. It is necessary for neuronal function and its depletion can produce neurological symptoms such as cramps or seizures. Clinical consequences of its deficit in the cerebellum are less known and the diagnosis can be delayed because of the lack of awareness on this condition.

Cases

We present three cases of cerebellar syndrome (CS) due to hypomagnesemia: A midline CS with myoclonus and ocular flutter and two cases of hemispheric CS, one of them entailed a Schmahmann's syndrome and the other suffered a seizure. MRI findings revealed cerebellar vasogenic edema and the symptoms improved after magnesium replacement in all cases.

Literature Review

We reviewed 22 cases of CS due to hypomagnesemia, all with subacute onset (days to weeks). Encephalopathy and/or epileptic seizures were common. MRI findings were vasogenic edema involving the cerebellar hemispheres, the vermis, or the nodule. Up to 50% of patients presented hypocalcemia and/or hypokalemia. All the patients showed symptomatic improvement after magnesium replacement, but 50% showed significant sequelae, and 46% relapsed.

Conclusions

Hypomagnesaemia should always be considered in the differential diagnosis of CS as it has a potential treatment, and its early recognition can avoid recurrences and permanent cerebellar impairment.

Vestibular Disorders after Kidney Transplantation: Focus on the Pathophysiological Mechanisms Underlying the Vertical Nystagmus Associated with Tacrolimus-Related Hypomagnesamia

The purpose of this paper is to present the case of a patient undergoing kidney transplantation who developed limb tremor dizziness and vertical nystagmus (ny) during Tacrolimus (TAC) therapy and to investigate the pathophysiological mechanisms underlying the balance disorder. This case study regards a 51-year old kidney transplant male patient with hand tremors and lower limbs asthenia associated with dizziness and nausea. The symptoms started two months after the beginning of intravenous TAC for renal transplantation. The pure-tone audiometry showed a mild symmetrical high-frequencies down-sloping sensorineural hearing loss. Acoustic emittance measures showed a normal tympanogram; stapedial reflexes were normally elicited. The Auditory Brainstem Responses (ABR) and Cervical Vestibular Evoked Myogenic Potentials (c-VEMPs) were bilaterally normally evoked. The bedside vestibular examination showed spontaneous down-beating stationary persistent, omni-positional nystagmus, not inhibited by fixation. The Head-Shaking Test accentuates the spontaneous ny. The horizontal clinical head impulse test was negative, bilaterally. A biochemical blood test revealed a decrease in Magnesium (Mg) levels (0.8 mg/dL; normal range 1.58–2.55). The integration of Mg induced both a plasma levels normalization and an improvement of clinical symptoms. This case suggests that TAC treatment can induce a Mg depletion that caused the transient cerebellar lesion. Therefore, the monitoring of serum electrolytes during immunosuppressive treatment appears to be a useful tool in order to reduce the central system symptomatology.

Downbeat nystagmus: a clinical review of diagnosis and management

PURPOSE OF REVIEW

This review will extensively cover the clinical manifestations, causes, diagnostic evaluation, and management strategies of downbeat nystagmus (DBN).

RECENT FINDINGS

Historically, MRI to assess for structural lesions at the cervicomedullary junction has been the primary diagnostic test in the evaluation of DBN since the 1980s. In recent years, there is increasing awareness of nonstructural causes of DBN including gluten ataxia, nutritional deficiencies, and paraneoplastic syndromes, among others. Medical management with aminopyridines has become first-line therapy in addition to disease-specific therapies.

SUMMARY

DBN is a common form of acquired nystagmus and the differential diagnosis remains broad, including both benign and potentially fatal causes. For practical purposes, the causes can be categorized as structural vs. nonstructural with MRI as the ideal, initial diagnostic study to differentiate the two. General therapeutic options include pharmacotherapy to enhance Purkinje cell function, strabismus surgery or prisms to shift null points, and behavioural changes. Disease-specific treatment is necessarily broad, though a significant proportion of patients will be idiopathic.

Hypomagnesemia-Induced Cerebellar Syndrome-A Distinct Disease Entity? Case Report and Literature Review

Clinical consequences of hypomagnesemia are manifold and include various neurological syndromes up to life-threatening conditions. Despite its importance, magnesium is generally not routinely determined leading to an under-recognition of hypomagnesemia-related disorders. In the past years, there are growing numbers of reports of hypomagnesemia-induced cerebellar syndromes (HiCS) with corresponding cerebellar edema, which might be a distinct disease entity. To provide further insights into HiCS, we describe a patient with HiCS and performed a literature review on cerebellar syndromes due to severe hypomagnesemia with regard to the clinical, MRI, and laboratory findings. We identified 17 cases, so including our case, 18 cases contribute to this review. Summarized, HiCS seems to be a distinct disease entity because of the remarkable similarities of clinical, MRI, and laboratory features. It should be diagnosed and treated early to avoid recurrent disease courses, residual symptoms, and potentially life-threatening conditions such as seizures. Physicians must be alert to HiCS as magnesium is usually not part of the routine electrolyte panel.

Posterior Reversible Encephalopathy Syndrome due to Hypomagnesemia: A Case Report and Literature Review

Background

Hypomagnesemia can cause various unspecific neurological complications, which can lead to diagnostic confusion. One of these complications is the posterior reversible encephalopathy syndrome (PRES), which is extremely uncommon and has been reported only twice in the English-language literature.

Case presentation

We report the case of a 60-year-old man who presented with PRES involving only the cerebellar hemispheres and associated with hypomagnesemia. After excluding all the other possible etiologies of PRES, we started magnesium replacement therapy, which led to a remarkable but fluctuating clinical and chemical improvement. A full recovery with no need for further supplementation was achieved only after discontinuation of a proton pump inhibitor.

Conclusions

This case highlights the role of magnesium in the pathophysiology of PRES; thereby, underlying hypomagnesemia should be considered in every PRES case with unclear etiology.

An eye for an I: a 35-year-old woman with fluctuating oculomotor deficits and dissociative identity disorder

Physiologic changes, including neurological or pseudo-neurological symptoms, occur across identity states in dissociative identity disorder DID) and can be objectively measured. The idea that dissociative phenomena might be associated with changes in brain function is consistent with research on the brain effects of hypnosis. The authors report a case of psycho-physiologic differences among 4 alter personalities manifested by a 35-year-old woman with DID. Differences in visual acuity, frequency of pendular nystagmus, and handedness were observed in this patient both when the alter personalities appeared spontaneously and when elicited under hypnosis. The authors consider several diagnostic possibilities for these findings and discuss whether prevailing treatment recommendations for DID patients could possibly be modified to ameliorate such visual and neurologic symptoms.

Reversible hypomagnesaemia-induced subacute cerebellar syndrome

Magnesium is the second most abundant intracellular cation and is a fundamental cofactor in a multitude of cellular enzymatic reactions. Magnesium deficiency causes diverse clinical features predominantly due to cardio- and neurotoxicity. We describe a case of severe hypomagnesaemia associated with intermittent downbeat nystagmus, cerebellar ataxia, generalised convulsions and a supraventricular tachycardia. On MRI imaging, a transient lesion of the cerebellar nodulus was observed, which has not, to our knowledge, been previously described in isolated hypomagnesaemia.

New genetic, pathophysiologic, and therapeutic issues in nystagmus

Nystagmus may have onset in infancy or adulthood. Infantile-onset nystagmus is commonly associated with genetic disease, and recognition of the various genetic and nongenetic diseases in which it may develop has led to the understanding that nystagmus is often a response of the oculomotor system to an early-onset, bilateral abnormality of vision. Adult-onset nystagmus most often develops as a result of nongenetic neurologic disease, and it manifests in a variety of patterns. Genetic studies have allowed further identification of the genes and genetic loci associated with nystagmus, and careful eye-movement recordings in patients with various patterns of nystagmus have further clarified the oculomotor pathophysiology.

[Type I Chiari malformation: report of 2 cases with unusual clinical presentation]

We describe two patients with Chiari type I malformation with unusual clinical presentation. The first one with clinical picture of acute respiratory insufficiency and the second one with vestibular and mild cerebellar syndrome and headache. In both cases the neurological examination demonstrated the presence of "down-beating nystagmus". We emphasize the value of neurological semiology, determining a correct complementary evaluation and effective treatment.