Cerebellar ataxia and sensory ganglionopathy associated with light-chain myeloma

Clinical whole Exome Sequencing Reveals Novel Homozygous Missense Variant in the PMPCA Gene causing Autosomal Recessive Spinocerebellar Ataxia

Background & Objective

Autosomal recessive cerebellar ataxias (ARCA) are rare heterogenous neurodegenerative disorders characterized by degeneration of the cerebellum and spinal cord with an early onset before the age of 20 years. PMPCA (MIM: 613036), is a key enzyme in mitochondrial protein processing which is critical for cell survival and growth. Our objective was to investigate Peptidase, Mitochondrial Processing Subunit Alpha (PMPCA) mutations linked with Spinocerebellar ataxia, autosomal recessive 2 (SCAR2).

Method

In the current study, Whole Exome Sequencing (WES) was done followed by Sanger sequencing for the validation of the WES results.

Results

WES results identified a novel homozygous variant, NM_015160.2: c.802C>T p.(Arg268Trp) in PMPCA gene. Mutation in this gene leads to progressive cerebellar ataxia with fine motor skills difficulties, intentional tremors, slow slurred speech and learning difficulties in a 12-year-old Saudi patient. WES results were further validated by Sanger sequencing technique.

Conclusions

Identified phenotype in our case was similar as previously described for SCAR2 related conditions. To our knowledge, this is the first reported mutation in PMPCA gene leading to SCAR2 in Saudi Arabia. These findings will enrich the scarce literature, further provide a new insight on the role of PMPCA gene-related disorders leading to SCAR2 and expand the disease concept. In addition, this will help to establish a database for the disease and its causative factors will further help in controlling diseases resulting from consanguinity in Saudi population.

A patient with neuropathy and ataxia: what do I have to consider?

PURPOSE OF REVIEW

An increasing number of peripheral neuro(no)pathies are identified as involving other components of the neurological system, particularly those that further impair balance. Here we aim to outline an evidence-based approach to the diagnosis of patients who present with a somatosensory disorder which also involves at least one other area of neurological impairment such as the vestibular, auditory, or cerebellar systems.

RECENT FINDINGS

Detailed objective investigation of patients who present with sensory impairment, particularly where the degree of imbalance is greater than would be expected, aids the accurate diagnosis of genetic, autoimmune, metabolic, and toxic neurological disease.

SUMMARY

Diagnosis and management of complex somatosensory disorders benefit from investigation which extends beyond the presenting sensory impairment.

Optokinetic Analysis in Patients With Spontaneous Horizontal Gaze-Evoked Nystagmus Without Radiological Neuropathology

Gaze-evoked nystagmus is not rare among those who have acute balance problem and may indicate a cerebellar dysfunction that is associated with a broad spectrum of disorders. The aim of this study is to analyze optokinetic response in those patients. Eleven males and 7 females (age range: 25-60, 42.5 [9.75]) with gaze-evoked nystagmus were analyzed with optokinetic test (Micromed Inc). Nystagmus was elicited by a stimulator light spot moving across the patient's visual field at a target speed of 30 degree/second. Ten age-matched healthy participants served as controls. The gain and slow-phase velocity difference in oculomotor response from left and right stimulus was compared in patients and the control participants. One-way analysis of variance test was used for multiple variance analysis of the groups. Statistical significance was set at P < .05. Slow-phase velocity of gaze-evoked nystagmus was ranging between 6 and 19 degree/second. The mean slow-phase velocity of gaze-evoked nystagmus to the right and left was 8.1 (3.81) and 6.8 (4.67) degree/second, respectively. Optokinetic gain was out of normal limits in 10 (55.5%) patients. Comparison of mean gain difference between the patients and the normal participants was statistically significant (P = .025). No statistical difference was found in mean slow-phase velocity difference in optokinetic nystagmus between control participants and patients (P > .05 [.099]). An acute-onset balance problem may be associated with dysfunction of separate populations of neurons in the brainstem and cerebellum even if there is no radiological neuropathy since gaze-evoked nystagmus is a sign of neural integrator dysfunction. Patients with gaze-evoked nystagmus and optokinetic abnormalities may have disruption of cerebellar pathways and should be followed closely.

Axillary motor nerve conduction study: Description of technique and provision of normative data

BACKGROUND

Axillary nerve lesions can commonly occur secondary to trauma or brachial plexopathy. Our aim was to describe our technique of axillary nerve motor conduction studies and provide the respective normal values.

METHODS

Active electrode was positioned over the most prominent portion of the middle deltoid, approximately 5-7 cm distal to the acromion. Reference electrode was positioned over the acromion. Ground electrode was placed between the active and the reference electrodes. Supramaximal stimulation was at the Erb's point.

RESULTS

A total of 154 participants (61% male, age range 18-84) were included. There was a significant positive correlation between the subjects' age and the onset latency (Spearman's rho 0.312, p < 0.001) and a significant negative correlation between the participants' age and the CMAP (Spearman's rho -0.481, p < 0.001). For the total male population the lower normal value for the CMAP was 7.6 mV and the higher normal value for the onset latency was 5.0 ms. For the total female population the respective normal values were 6.5 mV and 3.5 ms. In order to detect an axillary nerve lesion, asymmetry of >40% in the CMAPS between the symptomatic and the asymptomatic side show a sensitivity of 95.2% and a specificity of 96.6%.

CONCLUSION

We described our technique of axillary nerve motor conduction studies and provided the respective normal values stratified for age and gender. When suspecting an axillary nerve lesion it is always worth performing axillary motor NCS bilaterally and compare the CMAPs.

Cerebellar ataxia with sensory ganglionopathy; does autoimmunity have a role to play?

Background and purpose

Cerebellar ataxia with sensory ganglionopathy (SG) is a disabling combination of neurological dysfunction usually seen as part of some hereditary ataxias. However, patients may present with this combination without a genetic cause.

Methods

We reviewed records of all patients that have been referred to the Sheffield Ataxia Centre who had neurophysiological and imaging data suggestive of SG and cerebellar ataxia respectively. We excluded patients with Friedreich’s ataxia, a common cause of this combination. All patients were screened for genetic causes and underwent extensive investigations.

Results

We identified 40 patients (45% males, mean age at symptom onset 53.7 ± 14.7 years) with combined cerebellar ataxia and SG. The majority of patients (40%) were initially diagnosed with cerebellar dysfunction and 30% were initially diagnosed with SG. For 30% the two diagnoses were made at the same time. The mean latency between the two diagnoses was 6.5 ± 8.9 years (range 0–44). The commonest initial manifestation was unsteadiness (77.5%) followed by patchy sensory loss (17.5%) and peripheral neuropathic pain (5%).

Nineteen patients (47.5%) had gluten sensitivity, of whom 3 patients (7.5%) had biopsy proven coeliac disease. Other abnormal immunological tests were present in another 15 patients. Six patients had malignancy, which was diagnosed within 5 years of the neurological symptoms. Only 3 patients (7.5%) were classified as having a truly idiopathic combination of cerebellar ataxia with SG.

Conclusion

Our case series highlights that amongst patients with the unusual combination of cerebellar ataxia and SG, immune pathogenesis plays a significant role.

Pain in Platin-Induced Neuropathies: A Systematic Review and Meta-Analysis

Introduction

Platin-induced peripheral neuropathy (PIPN) is a common cause of PN in cancer patients. The aim of this paper is to systematically review the current literature regarding PIPN, with a particular focus on epidemiological and clinical characteristics of painful PIPN, and to discuss relevant management strategies.

Methods

A systematic computer-based literature search was conducted on the PubMed database.

Results

This search strategy resulted in the identification of 353 articles. After the eligibility assessment, 282 articles were excluded. An additional 24 papers were identified by scanning the reference lists. In total, 95 papers met the inclusion criteria and were used for this review. The prevalence of neuropathic symptoms due to acute toxicity of oxaliplatin was estimated at 84.6%, whereas PN established after chemotherapy with platins was estimated at 74.9%. Specifically regarding pain, the reported prevalence of pain due to acute toxicity of oxaliplatin was estimated at 55.6%, whereas the reported prevalence of chronic peripheral neuropathic pain in PIPN was estimated at 49.2%.

Conclusion

Peripheral neuropathy is a common complication in patients receiving platins and can be particularly painful. There is significant heterogeneity among studies regarding the method for diagnosing peripheral neuropathy. Nerve conduction studies are the gold standard and should be performed in patients receiving platins and complaining of neuropathic symptoms post-treatment.

Rapid neurophysiological screening for sensory ganglionopathy: A novel approach

BACKGROUND AND AIM

Pure sensory neuropathies involving the dorsal root ganglia are commonly referred to as sensory ganglionopathies (SG). Causes of SG can be inherited (as seen in Friedreich's ataxia) or acquired (e.g. immune-mediated or paraneoplastic). Diagnostic criteria for confirming SG have been published and consist of a combination of clinical and neurophysiological parameters. The aim of our study was to develop a neurophysiological method for rapid screening for diagnosis of SG.

METHODS

For each subject we obtained the sensory nerve action potentials (SNAPs) of five nerves (median, ulnar, radial, sural and superficial peroneal) bilaterally. In the presence of an entrapment neuropathy we obtained the SNAP of the medial antebrachial cutaneous nerves bilaterally. We estimated the number of pairs of nerves showing a SNAP asymmetry of >50% (difference of SNAPs/ lower SNAP).

RESULTS

Sixty-eight subjects, 34 patients with SG and 34 age and sex-matched controls, participated in the study. Among all subjects using a receiver operating characteristic (ROC) curve analysis, the area under the curve was 0.984 (95% CI, 0.960-1.000; SE, 0.012; p < .001). In order to detect SG, presence of SNAP asymmetry of >50% in 2 pairs of nerves, not explained by an entrapment neuropathy, shows a sensitivity of 97.1%, a specificity of 94.1%, a positive predictive value of 94.3% and a negative predictive value of 97.0.

CONCLUSION

The number of pairs of nerves showing a SNAP asymmetry of >50% may be used as a novel rapid screening tool of patients with SG.

Pain as a First Manifestation of Paraneoplastic Neuropathies: A Systematic Review and Meta-Analysis

INTRODUCTION

Paraneoplastic neurological syndromes (PNS) consist of a heterogeneous group of neurological disorders triggered by cancer. The aim of this systematic review is to estimate the reported prevalence of pain in patients with paraneoplastic peripheral neuropathy (PPN).

METHODS

A systematic computer-based literature search was conducted on PubMed database.

RESULTS

Our search strategy resulted in the identification of 126 articles. After the eligibility assessment, 45 papers met the inclusion criteria. Full clinical and neurophysiological data were further extracted and involved 92 patients with PPN (54.5% males, mean age 60.0 ± 12.2 years). The commonest first manifestation of PPN is sensory loss (67.4%), followed by pain (41.3%), weakness (22.8%), and sensory ataxia (20.7%). In 13.0% of the cases, pain was the sole first manifestation of the PPN. During the course of the PPN, 57.6% of the patients may experience pain secondary to the neuropathy.

CONCLUSIONS

Pain is very prevalent within PPN. Pain specialists should be aware of this. Detailed history-taking, full clinical examination, and requesting nerve conduction studies might lead to an earlier diagnosis of an underlying malignancy.

Painful Peripheral Neuropathy and Cancer

Peripheral neuropathy (PN) is very prevalent in cancer patients and a leading cause of pain related to cancer. However, the underlying pathophysiological mechanisms vary significantly. Peripheral neuropathy can be a direct or an indirect complication of cancer or cancer-related treatment, or a pre-existing comorbidity not related to cancer. PN might also occur as a paraneoplastic neurological syndrome. Such syndromes are immune-mediated manifestations that usually precede the diagnosis of cancer or cancer’s relapse. Pain is very prevalent in paraneoplastic peripheral neuropathies and, therefore, merits attention.