Distressing belching and neuroacanthocytosis

Pallidus Stimulation for Chorea-Acanthocytosis: A Systematic Review and Meta-Analysis of Individual Data

A significant proportion of patients with chorea-acanthocytosis (ChAc) fail to respond to standard therapies. Recent evidence suggests that globus pallidus internus (GPi) deep brain stimulation (DBS) is a promising treatment option; however, reports are few and limited by sample sizes. We conducted a systematic literature review to evaluate the clinical outcome of GPi-DBS for ChAc. PubMed, Embase, and Cochrane Library databases were searched for relevant articles published before August 2021. The improvement of multiple motor and nonmotor symptoms was qualitatively presented. Improvements in the Unified Huntington’s Disease Rating Scale motor score (UHDRS-MS) were also analyzed during different follow-up periods. A multivariate linear regression analysis was conducted to identify potential predictors of clinical outcomes. Twenty articles, including 27 patients, were eligible. Ninety-six percent of patients with oromandibular dystonia reported significant improvement. GPi-DBS significantly improved the UHDRS-motor score at < 6 months (p < 0.001) and ≥ 6 months (p < 0.001). The UHDRS-motor score improvement rate was over 25% in 75% (15/20 cases) of patients at long-term follow-up (≥ 6 months). The multiple linear regression analysis showed that sex, age at onset, course of disease, and preoperative movement score had no linear relationship with motor improvement at long-term follow-up (p > 0.05). GPi-DBS is an effective and safe treatment in most patients with ChAc, but no reliable predictor of efficacy has been found. Oromandibular dystonia-dominant patients might be the best candidates for GPi-DBS.

Short and long term outcome of bilateral pallidal stimulation in chorea-acanthocytosis

Background

Chorea-acanthocytosis (ChAc) is a neuroacanthocytosis syndrome presenting with severe movement disorders poorly responsive to drug therapy. Case reports suggest that bilateral deep brain stimulation (DBS) of the ventro-postero-lateral internal globus pallidus (GPi) may benefit these patients. To explore this issue, the present multicentre (n=12) retrospective study collected the short and long term outcome of 15 patients who underwent DBS.

Methods

Data were collected in a standardized way 2-6 months preoperatively, 1-5 months (early) and 6 months or more (late) after surgery at the last follow-up visit (mean follow-up: 29.5 months).

Results

Motor severity, assessed by the Unified Huntington’s Disease Rating Scale-Motor Score, UHDRS-MS), was significantly reduced at both early and late post-surgery time points (mean improvement 54.3% and 44.1%, respectively). Functional capacity (UHDRS-Functional Capacity Score) was also significantly improved at both post-surgery time points (mean 75.5% and 73.3%, respectively), whereas incapacity (UHDRS-Independence Score) improvement reached significance at early post-surgery only (mean 37.3%). Long term significant improvement of motor symptom severity (≥20 % from baseline) was observed in 61.5 % of the patients. Chorea and dystonia improved, whereas effects on dysarthria and swallowing were variable. Parkinsonism did not improve. Linear regression analysis showed that preoperative motor severity predicted motor improvement at both post-surgery time points. The most serious adverse event was device infection and cerebral abscess, and one patient died suddenly of unclear cause, 4 years after surgery.

Conclusion

This study shows that bilateral DBS of the GPi effectively reduces the severity of drug-resistant hyperkinetic movement disorders such as present in ChAc.

Clinical and molecular research of neuroacanthocytosis

Neuroacanthocytosis is an autosomal recessive or dominant inherited disease characterized by widespread, non-specific nervous system symptoms, or spiculated "acanthocytic" red blood cells. The clinical manifestations typically involve chorea and dystonia, or a range of other movement disorders. Psychiatric and cognitive symptoms may also be present. The two core neuroacanthocytosis syndromes, in which acanthocytosis is atypical, are autosomal recessive chorea-acanthocytosis and X-linked McLeod syndrome. Acanthocytes are found in a smaller proportion of patients with Huntington's disease-like 2 and pantothenate kinase-associated neurodegeneration. Because the clinical manifestations are diverse and complicated, in this review we present features of inheritance, age of onset, neuroimaging and laboratory findings, as well as the spectrum of central and peripheral neurological abnormalities and extraneuronal involvement to help distinguish the four specific syndromes.

Developments in neuroacanthocytosis: Expanding the spectrum of choreatic syndromes

As with other neurodegenerative disorders, research into the group of diseases known under the umbrella term of "neuroacanthocytosis" has greatly benefited from the identification of causative genes. The distinct and unifying aspect of these disorders is the presence of thorny deformations of circulating erythrocytes. This may be due to abnormal properties of red cell membranes, which could lead to insights into mechanisms of neurodegeneration. Research approaches in this field, in addition to examining functions and protein interactions of the affected proteins with particular respect to neurons, have also drawn upon the expertise of hematologists and red cell membrane biologists. In this article, recent developments in the field are presented.

Identification of a VPS13A founder mutation in French Canadian families with chorea-acanthocytosis

Mutations in VPS13A cause chorea-acanthocytosis (ChAc), an autosomal recessive neurodegenerative disorder. VPS13A is located in a tail-to-tail arrangement with GNA14 on chromosome 9q21. ChAc shows substantial allelic heterogeneity, with no single VPS13A mutation causing the majority of cases. We examined 11 patients in four French Canadian ChAc pedigrees for mutations in VPS13A. Affected members of three families were homozygous for a 37-kb deletion of the four terminal exons of VPS13A (EX70_EX73del). This deletion also encompasses the two terminal exons of GNA14. Two affected females in family 4 were homozygous for the splicing mutation 4242+1G>T. Remarkably, the affected males in this highly consanguineous pedigree were compound heterozygotes for EX70_EX73del and 4242+1G>T. PCR analysis of the deletion breakpoint junction revealed that an additional patient with French Canadian ancestry was heterozygous for the EX70_EX73del allele. The identification of a common 9q21 haplotype associated with EX70_EX73del in at least four apparently unrelated ChAc families implies that ChAc shows a founder effect in French Canadians, and that routine testing for EX70_EX73del in suspected ChAc cases may therefore be worthwhile in this population. The deletion breakpoint PCR described here will enable rapid identification of both homozygous and heterozygous carriers of EX70_EX73del.

Neuroacanthocytosis

PURPOSE OF REVIEW

The term neuroacanthocytosis describes a group of phenotypically and genetically heterogeneous disorders, and thus has long been a source of confusion and diagnostic imprecision. It is vital to distinguish between the lipoprotein deficiency disorders which affect gait, but do not cause movement disorders or neuropsychiatric problems, and the diseases described here, of which these are characteristic features. This review summarizes the current state of knowledge regarding this group of diseases in order to facilitate clinical recognition, accurate diagnosis and appropriate management.

RECENT FINDINGS

Advances in molecular medicine have enabled us to distinguish precisely among the disorders described under the label of neuroacanthocytosis, most notably between autosomal recessive chorea-acanthocytosis and the X-linked McLeod syndrome. This has facilitated appreciation of the range of phenotypes in each of the various conditions. Acanthocytosis is also found in a smaller percentage of cases with pantothenate kinase-associated neurodegeneration (PKAN) and Huntington's disease-like 2 (HDL2). An improved method of determination of acanthocytosis has been described, which if adopted as standard practice may facilitate detection of these conditions.

SUMMARY

Genetic testing has led to increased diagnostic accuracy of the neuroacanthocytosis syndromes, which is essential to extend recognition of these disorders, as well as to improve understanding of the disease process. Most importantly, given the absence of a cure, it is vital for appropriate genetic counselling. Treatments, as in other neurodegenerative conditions, are at present limited to symptomatic therapies.