Leg restlessness and hyperparathyroidism in Parkinson's disease, a further clue to RLS pathogenesis?

Prevalence and clinical profile of patients with restless legs syndrome in Parkinson's disease: A meta-analysis

INTRODUCTION

Restless legs syndrome (RLS) is a sensorimotor disorder of sleep/wake regulation characterized by an urge to move the legs accompanied by a wide range of sensory symptoms, mainly affecting the lower limbs. An increased incidence of RLS has been demonstrated in Parkinson's disease (PD) and has been associated with severe motor and non-motor manifestations. We aimed to provide a reliable estimate of RLS prevalence and the clinical features associated with its occurrence in PD (PD-RLS).

METHODS

We performed a systematic literature search up to January 2024 using PubMed, Scopus, and PsycINFO databases. Articles were included if they provided data on PD patients with or without RLS, and these proportions were used to estimate the prevalence of PD-RLS. Clinical profile associated with PD-RLS was explored by comparing the clinical characteristics of PD patients with and without RLS.

RESULTS

Forty-six studies were included in the meta-analysis. Pooled RLS prevalence was 20 % of a total sample of 6990 PD patients and was associated with female sex, mixed motor phenotype, worse motor disturbances and functional disability, and a wide range of non-motor symptoms such as sleep disorders, cognitive and autonomic dysfunctions, and more severe neuropsychiatric manifestations. Sensitivity analyses indicated significant associations of PD-RLS with variables related to dopaminergic therapy. No association was found with serum ferritin, serum iron and hemoglobin levels.

CONCLUSIONS

The prevalence of PD-RLS exceeds that reported in the general population, suggesting the existence of a relationship between the two disorders. Dopaminergic treatment seems to play an ambivalent role relieving, worsening or "mimicking" RLS manifestations. However, the clinical profile of PD-RLS patients, characterized by a greater severity of non-motor symptoms, also suggests that neurotransmitter systems other than the dopaminergic one are involved in PD-RLS etiology.

Application of Repetitive Transcranial Magnetic Stimulation for the Treatment of Restless Legs Syndrome: A Pilot Study

OBJECTIVE

To explore effects of high-frequency repetitive transcranial magnetic stimulation (rTMS) on patients with restless legs syndrome (RLS).

METHODS

In total, 18 patients with primary RLS were divided into rTMS group and sham stimulation group. The rTMS treatment group received 15-Hz high-frequency rTMS to stimulate the leg motor representative area of the frontal cortex for 14 days, and the sham stimulation group received 15 Hz high-frequency rTMS sham stimulation in primary motor cortex for 14 days.

RESULTS

After rTMS, RLS severity scale score, Pittsburgh Sleep Quality Index (PSQI), Hamilton Anxiety Scale (HAMA), as well as Hamilton Depression Rating Scale 24 (HAMD24) in rTMS treatment group were significantly lower than before treatment; 1 month and 2 months after treatment, the score remained at low level. Meanwhile, no significant changes have been observed in the aforementioned index before rTMS stimulation for the sham stimulation group after 14 days or after 1 month and 2 months. In addition, the results of correlation analysis suggested for all the 18 patients with RLS, there was a positive correlation between PSQI score and HAMA as well as HAMD24 scores before and after rTMS stimulation. In addition, the RLS severity score was also positively correlated with PSQI, HAMA, and HAMD24 scores.

CONCLUSIONS

High-frequency rTMS stimulation reduces the frequency and severity of RLS; improves the quality of sleep, anxiety, as well as depression of the patients; and the curative effect can be sustained for 2 months. High-frequency rTMS may be used as an alternative treatment option for improving the quality of life of patients with RLS.

Restless leg syndrome as a complication of primary hyperparathyroidism: insights from a retrospective study

INTRODUCTION

Restless leg syndrome (RLS) is an invalidating neurological disorder with a complex, largely unknown pathophysiology. While RLS is observed in Parkinson's disease and in renal failure, idiopathic cases are common. Limited reports associate RLS with parathyroid hormone (PTH). This study analyzes a cohort of patients with primary hyperparathyroidism (PHPT) and chronic post-surgical hypoparathyroidism (hypo PTH), to investigate RLS prevalence, and associated risk factors.

METHODS

Ninety-five patients (54 PHPT, 41 hypo PTH) were consecutively enrolled at the bone metabolism outpatient clinic. The revised IRLSSG diagnostic criteria were used to diagnose RLS, with assessments conducted through face-to-face interviews and neurological examination. When RLS was confirmed, the RLS severity scale was applied. Retrospective records included calcium-phosphate metabolism-related parameters, surgery details, renal lithiasis, fragility fractures, and densitometric features (T-score).

RESULTS

RLS was diagnosed in 22.2% PHPT patients, compared to 4.9% of patients with hypo PTH (p = 0.02). Of RLS diagnosed patients, 91.7% had a history of parathyroidectomy, compared to 47.6% of patients without RLS (p = 0.01). Most of the operated patients reported that surgery determined an improvement of symptoms; however, mean score severity of RLS at our evaluation was 15/40, defined as moderate. PTH and calcium levels were not statistically associated to the presence of RLS.

CONCLUSION

Our study suggests that PHPT may be one of the etiologies of RLS. Parathyroidectomy alleviates symptoms in the vast majority of the cases but does not remove them.

Unveiling the pathophysiology of restless legs syndrome through transcriptome analysis

The aim of this study was to analyze signaling pathways associated with differentially expressed messenger RNAs in people with restless legs syndrome (RLS). Seventeen RLS patients and 18 controls were enrolled. Coding RNA expression profiling of 12,857 gene transcripts by next-generation sequencing was performed. Enrichment analysis by pathfindR tool was carried-out, with p-adjusted ≤0.001 and fold-change ≥2.5. Nine main different network groups were significantly dysregulated in RLS: infections, inflammation, immunology, neurodegeneration, cancer, neurotransmission and biological, blood and metabolic mechanisms. Genetic predisposition plays a key role in RLS and evidence indicates its inflammatory nature; the high involvement of mainly neurotropic viruses and the TORCH complex might trigger inflammatory/immune reactions in genetically predisposed subjects and activate a series of biological pathways-especially IL-17, receptor potential channels, nuclear factor kappa-light-chain-enhancer of activated B cells, NOD-like receptor, mitogen-activated protein kinase, p53, mitophagy, and ferroptosis-involved in neurotransmitter mechanisms, synaptic plasticity, axon guidance, neurodegeneration, carcinogenesis, and metabolism.