Restless legs syndrome. Pathophysiology, diagnosis and treatment

Restless legs syndrome is the most prevalent sleep-related movement disorder, affecting 5-10% of the population, characterized by an urge to move that appears during rest or is exacerbated by rest, primarily in the lower extremities, that occurs in the evening or night and that disappears during movement or is improved by movement. Restless legs syndrome significantly impacts sleep, mood, and quality of life. Its pathophysiology involves a complex interplay of genetic and environmental factors, as well as comorbidities, leading to alterations in brain iron resulting in dysfunction in dopaminergic, adenosine, and glutamatergic pathways. Treatment typically includes iron supplementation and symptomatic therapy, traditionally utilizing dopamine agonists. However, their long-term use may exacerbate symptoms, relegating them to second-line treatment after ligands α2δ of calcium channels.

Preoperative treatment with dopamine agonist therapy influences surgical outcome in prolactinoma: a retrospective single-center on 159 patients

INTRODUCTION

Prolactinoma account to the most common pituitary adenomas and current therapy regime constitutes of dopamine agonist therapy (DA) and surgery in selected cases [17]. Due to tumor fibrosis induced by previous DA therapy, surgical removal can be challenging though. Therefore, this study investigates how preoperative DA usage influences perioperative treatment and surgical outcome in prolactinoma and aims to ascertain whether a specific subgroup of prolactinoma patients could derive greater benefit from exclusive surgical intervention.

METHODS

We retrospectively analyzed n = 159 surgically treated and histologically confirmed prolactinomas in the sella region from 2013-2022 in our institution. Clinical, radiological and surgical features were analyzed. Univariate and multivariate analyses were performed.

RESULTS

Out of total of 159 prolactinoma patients, 83.6% received previous treatment with DA followed by surgery, while only 16.4% received exclusive surgery. Both groups presented similar initial tumor volumes (1.9cm3 vs. 1.5cm3, p = 0.59) and equal preoperative prolactin levels (PRL) (199.7 µg/l vs. 191.0 µg/l, p = 0.44). Surgical procedures took significantly longer when patients received prior DA treatment (79 min. vs. 70 min., p = 0.0479). Six months after surgery, pretreated patients revealed significantly higher PRL compared to non-treated (107 g/l vs. 8.64 µg/, p = 0.0009). Additionally, untreated microprolactinoma presented a remission of 100%, whereas pretreated exhibited a remission rate of 88.75%.

CONCLUSION

The current study demonstrates that prior DA treatment is associated with significantly longer surgeries, higher recurrence rates and lower rates of normalization of PRL levels after surgery, particularly in microprolactinomas and support the latest recommendations of the Pituitary Society's Consensus Statement 2023, which favors the option of surgery alone as first-line therapy for microprolactinomas.

Characteristics and outcomes of men with erectile dysfunction as the presenting symptom due to a lactotroph adenoma

PURPOSE

Erectile dysfunction (ED) is frequently underreported in men suffering from prolactinomas and can be challenging to manage. Both dopamine agonists (DAs) and transsphenoidal surgery (TSS) correct hyperprolactinemia and restore gonadal function. However, there is scarce data regarding their effectiveness in correcting ED over the long term.

METHODS

This study is a retrospective single-center comparative cohort study analyzing men diagnosed with prolactinomas, both with and without confirmed erectile dysfunction (ED) at diagnosis. Independent risk factors for persistent ED over the long term were examined using multivariate logistic regression.

RESULTS

Among the 39 men with lactotroph adenomas, ED was one of the presenting symptoms in 22 (56%). The mean age at diagnosis was 45 ± 12 years. Surgery was the primary treatment in 6 (27%) ED patients and 8 (47%) non-ED patients. After a mean follow-up of 74 ± 48 months, remission from hyperprolactinemia was achieved in the majority (76%) of men: 71% in the non-ED cohort and 81% in the ED group (p = 0.70), regardless of the primary treatment strategy (surgical 84% versus medical 72%, p = 0.46). Long-term remission of ED was noted in 16 (73%) patients. Interestingly, high baseline BMI levels emerged as potential risk factors for persistent ED over the long term (OR 1.4, 95%CI 1.0-1.9; p = 0.04), while neither the initial adenoma size nor the primary treatment strategy (i.e., TSS vs. DAs) reached statistical significance.

CONCLUSIONS

Correcting hyperprolactinemia and its associated hypogonadism significantly improves ED in the majority of men with prolactinomas over the long term, regardless of the primary treatment strategy employed. In addition to addressing endocrine deficiencies, the early initiation of weight control programs may be considered for men with lactotroph adenomas and ED. Although our study suggests an association between BMI and the risk of persistent ED, further research is needed to establish any causal relationships.

Dopamine agonists in restless leg syndrome treatment and their effects on sleep parameters: A systematic review and meta-analysis

BACKGROUND

Dopamine agonists (DAs) constitute the standard therapeutic scheme for restless leg syndrome (RLS) because they have been proven to be effective. However, DAs may change sleep parameters, thus having adverse effects on patient condition. This meta-analysis clarified the effects of DAs used in RLS treatment on the sleep architecture.

METHODS

PubMed, Embase, and Cochrane Central databases were searched for randomized control trials (RCT) (up to October 2023) that discussed the effects of DAs on sleep architecture in patients with RLS. A meta-analysis employing a random-effects model was conducted. The patients were divided into subgroups according to individual DAs and treatment duration (1 day or ≥4 weeks).

RESULTS

Thirteen eligible randomized placebo-controlled trials were included in the assessment. The effects of three DAs (i.e., pramipexole, ropinirole, and rotigotine) on rapid eye movement (REM) sleep, slow-wave sleep (SWS), and sleep efficiency (SE) were analyzed. Overall, pramipexole significantly improved SE but decreased the percentage of REM sleep among treated patients. Ropinirole also enhanced SE compared with the placebo group. Rotigotine did not affect SE and REM sleep. Subgroup analysis found that pramipexole used for 1 day and ≥4 weeks significantly diminished the percentage of REM sleep. Ropinirole used for 1 day showed similar REM sleep patterns. Finally, none of the three DAs affected SWS.

CONCLUSIONS

This meta-analysis demonstrated that DAs significantly affect sleep parameters.

Effect of Cabergoline on weight and glucose metabolism in patients with acromegaly

PURPOSE

Cabergoline (CAB) has shown to have benefic effects on the metabolism in different clinical settings but its metabolic role in acromegaly disease has not been studied yet. Aim of our study was to evaluate the impact of CAB on glucose metabolism and weight in patients with acromegaly.

METHODS

All patients with acromegaly undergoing continuous treatment with CAB for at least 6 months were retrospectively screened. Exclusion criteria were discontinuation of CAB for more than one month, change of antidiabetic or other therapy for acromegaly, concomitant untreated hormonal deficiency, initiation of pregnancy and/or breastfeeding. All patients were evaluated in terms of biochemical disease control, glucose metabolism and weight at baseline (T0) and after the introduction of CAB therapy at 6 (T6) and 12 months (T12).

RESULTS

Twenty-six patients (15 females and 11 males) were evaluated at T0 and T6 and 19 patients (12 females and 7 males) were also evaluated at T12. Insulin-like growth factor I (IGF-I) and prolactin (PRL) levels were significantly lower at T6 and T12 compared to baseline (p < 0.001 for IGF-I, p < 0.05 for PRL) even if no further differences were observed between T12 and T6. Considering the entire cohort, no differences were appreciated regarding the metabolic parameters but a significant reduction in weight and body mass index (BMI) was observed at both T6 (p = 0.009 for weight, p = 0.021 for BMI) and T12 (p = 0.014 for weight, p = 0.017 for BMI) compared to baseline.

CONCLUSION

Our results confirm the efficacy of CAB in providing a significant improvement in the biochemical disease control but do not demonstrate a marked benefit on glucose metabolism of acromegaly patients. In such patients, CAB appears to have a rapid effect on weight and BMI, with significant changes noticeable as early as 6 months and persisting for at least 12 months.

Aromatase inhibitors as a therapeutic strategy for male prolactinoma resistant to dopamine agonists: a retrospective cohort study and literature review

PURPOSE

To assess the effect of letrozole, an aromatase inhibitor (AI), in patients with resistant prolactinoma that presented an increase in serum prolactin (PRL) levels during testosterone replacement therapy (TRT).

METHODS

A retrospective cohort study in a single tertiary care center. From March 2012 to July 2023, 53 male patients over 18 years with prolactinoma were followed in our Neuroendocrine Unit. Of those, 90.6% presented macroadenomas, 41% of them were resistant to cabergoline and 25% presented persistent hypogonadism to whom TRT was indicated. Among them, five presented a significant increase in PRL levels and AI was initiated. All five patients had resistant prolactinomas. One of them was excluded due to tumor aggressiveness and concomitant use of temozolomide during AI therapy.

RESULTS

Four patients were included in the analysis, with a mean age of 28.5 (± 7.5) years, median prolactin of 1060 (600 to 6700) ng/mL and median of the largest tumor diameter of 3.6 (1.5 to 5) cm at the time of prolactinoma diagnosis. On TRT, all presented an increase in serum PRL levels (231 to 396%), with a subsequent decrease (61 to 93%) after adding AI. During AI treatment for a median time of 60.5 (21 to 120) months, tumor shrinkage was observed in two cases (-8 and -3 mm in the maximum diameter) and tumor stability in the other two. No major side effects occurred and AI was well tolerated.

CONCLUSION

AI might be an option for men with resistant prolactinoma who have an increase in PRL levels on TRT. Nevertheless, prospective randomized clinical trials are needed to ensure efficacy and security for this approach.

Impulse control disorders in patients with dopamine agonist-treated pituitary adenomas: a cross-sectional multicenter study

BACKGROUND

Impulse control disorders (ICDs) have been described as underrecognized side effects of dopamine agonists (DAs) in neurological disorders but are not sufficiently understood in endocrine conditions.

OBJECTIVE

To identify the prevalence of DAs induced ICDs and determine potential risk factors related to these disorders in patients with prolactinoma and non-function pituitary adenomas (NFPAs).

METHODS

This is a cross-sectional multicenter study involving 200 patients with prolactinoma and NFPAs, who received follow-ups in tertiary referral centers. DA-induced ICDs were assessed using ICD questionnaires modified from prior studies.

RESULT

At least one ICD was reported by 52% of participants, among whom 28.5% mentioned compulsive shopping, 24.5% punding, and 24.5% hypersexuality. Furthermore, 33% of the patients reported the presence of one type of ICD behavior, while 12% specified two and 7% had three types of such behavior. The multivariable logistic regression showed that the significant risk factors of ICD were younger age (adjusted odds ratio [AOR]: 0.92, 95% confidence interval [CI]: 0.88-0.97, p 0.001), being single (AOR: 0.15, 95%CI: 0.03-0.84, p 0.03), and a positive history of psychiatric illness (AOR: 7.67, 95% CI: 1.37-42.97, p 0.021).

CONCLUSION

ICDs with a broad range of psychiatric symptoms are common in individuals with DA-treated prolactinoma and NFPAs. Endocrinologists should be aware of this potential side effect, particularly in patients with a personal history of psychiatric disorder.

Selective attention towards infants in nulliparous women across the menstrual cycle

Research in women showed that testosterone is associated with decreased selective attention towards infant stimuli, which can be compensated for by oxytocin administration. In theory, caregiving behavior is thought to be mediated by oxytocin. Oxytocin binds to dopaminergic neurons and thus supposedly motivates aspects of caregiving through its influence on dopaminergic transmission. Most previous studies on caregiving behaviors were thereby performed in women under hormonal contraception to avoid hormonal fluctuations. However, recent studies repeatedly demonstrated decisive influences of the hormonal changes across the female menstrual cycle on dopamine-mediated behaviors, suggesting that estradiol acts as dopamine agonist in the follicular phase and progesterone as dopamine antagonist in the luteal phase. In the present study, we investigated selective attention towards infants as one central aspect of caregiving behavior over the natural menstrual cycle and in relation to interindividual differences of estradiol and progesterone. As expected, we found that women with higher estradiol in the follicular phase also showed higher selective attention towards infant faces among adult distractors, whereas the correlation disappeared in the luteal phase. In contrast, progesterone did not correlate with selective attention towards infants. The present findings collectively support the assumption that estradiol may act as dopamine agonist in the follicular phase, thereby supposedly promoting an important aspect of caretaking behavior.

Long-term dopamine agonist treatment fails to restore altered central sensory processing in restless legs syndrome: Evidence from current perception threshold measurements

OBJECTIVES

Although some studies have examined the impact of short-term dopamine agonist treatment on altered central sensory processing in patients with restless legs syndrome (RLS), there is a scarcity of research investigating the effect of long-term treatment with these drugs. The aim of this study is to investigate the long-term impact of dopamine agonist treatment on altered central sensory processing in RLS patients using current perception threshold (CPT) testing.

METHODS

We conducted a study of 24 RLS patients, measuring their CPT values before and after dopamine agonist treatment for at least 2 months. Patients were classified as responders or non-responders based on their decrease in International Restless Legs Syndrome (IRLS) score. Clinical parameters were collected and compared pre- and post-treatment.

RESULTS

The mean duration of treatment with dopamine agonist was 13.6 ± 11.0 months. Our results showed that dopamine agonist treatment significantly improved clinical parameters, including the IRLS score, Visual Analogue Scale, and RLS Quality of Life questionnaire. However, CPT values did not show significant changes for all stimulus frequencies after treatment. Furthermore, we did not find any difference in CPT values before and after treatment in both responders and non-responders.

CONCLUSIONS

Our study demonstrated that long-term treatment with dopamine agonists effectively reduces RLS symptoms, but does not reverse the altered central sensory processing observed on CPT testing in RLS patients. These results support the notion that the pathophysiology of RLS is multifactorial and not solely driven by dopaminergic dysfunction.

Prolactinomas Resistant to Dopamine Agonists: Pathophysiology and Treatment

Prolactinomas are the most common functional pituitary tumors, accounting for 40% of all pituitary adenomas. Medical treatment with dopamine agonists (DA), mainly cabergoline, is considered the primary therapy for these patients. Prolactin normalization is achieved in 80-90% of prolactinomas treated with cabergoline. Patients resistant to the standard dose can escalate the dose of cabergoline up to the maximum tolerated dose. The expression of dopamine (D2) receptors and dopamine affinity is decreased in aggressive and resistant prolactinomas. Patients with aggressive and DA-resistant adenomas or with rare PRL-secreting carcinomas can be treated off-label with temozolomide (TMZ), a DNA alkylating agent. TMZ is effective in 40-50% of treated lactotroph tumors showing at least a partial response. However, patients tend to escape from the effect of TMZ after a limited time of response. Other therapeutic options include aromatase inhibitors, the somatostatin receptor ligand pasireotide, peptide receptor radionuclide therapy (PRRT), immune-checkpoint inhibitors, tyrosine-kinase inhibitors, or everolimus, the mammalian target of rapamycin inhibitor. These experimental treatments were effective in some patients carrying refractory prolactinomas showing usually partial tumor control. However, the number of treated patients with any of these new therapeutic options is very limited and treatment results are inconsistent, thus additional experience with more patients is required.

Impulse Control Disorders in Patients with Pituitary Tumors Treated with Dopamine Agonists: A Systematic Review

BACKGROUND

The increased prevalence of Impulse Control Disorders (ICDs) in dopamine agonist (DA) treated patients with Parkinson's disease is well described. Despite the frequent use of DAs in the management of pituitary tumors, the relationship between DAs and prevalence of ICDs in patients with pituitary tumours is unclear.

AIMS

To establish the prevalence of ICDs in patients with prolactinoma or acromegaly and determine whether prevalence differs in those on DAs to those treated without.

METHODS

Systematic review of the literature (registered a priori) reporting prevalence of ICDs in patients with prolactinoma or acromegaly (conducted June 2023). A narrative synthesis describing prevalence of ICDs according to assessment method was performed. Prevalence comparisons between patients with prolactinoma or acromegaly treated with DAs, to patients treated without, were summarised.

RESULTS

Studies were largely retrospective, observational and heterogenous, with few patients with prolactinoma and acromegaly treated without DA. Prevalence of ICDs varied between 0-60% in patients with prolactinoma, and from 5-23% in studies with at least five patients with acromegaly. In most studies comparing DA exposed to non-DA exposed cases, DA use was not associated with ICDs.

CONCLUSIONS

Reported prevalence of ICDs in patients with prolactinoma and acromegaly varies considerably. Given ICDs were reported to be highly prevalent in some studies, clinicians should be mindful of these potentially serious disorders. ICD screening tools validated for use in patients with pituitary tumors combined with prospective studies including appropriate controls, are necessary to accurately establish prevalence of ICDs and true impact of DAs in their development.

Efficacy and Safety of Endoscopic Transsphenoidal Resection for Prolactinoma: A Retrospective Multicenter Case-series

BACKGROUND

Endoscopic transsphenoidal surgery (ETSS) for prolactinoma is reserved for dopamine agonist (DA) resistance, intolerance, or apoplexy. High remission (overall 67%, microprolactinoma up to 90%), low recurrence (5-20%) rates highlighted that surgery might be first-line treatment.

AIMS

To report on outcomes of ETSS in a cohort of prolactinomas.

METHODS

Multicenter retrospective cohort of 137 prolactinoma patients (age 38.2 ± 13.7 years; 61.3% female, median follow-up 28.0 [15.0-55.5] months) operated between 2010-2019 with histopathological confirmation.

RESULTS

Median preoperative prolactin levels were 166 (98-837 µg/L; males 996 [159-2145 µg/L] vs. females 129 [84-223 µg/L], p <0.001). 56 (40.9%) microprolactinomas, 69 (50.4%) macroprolactinomas, and 7 (5.1%) giant prolactinomas were included, whereas no adenoma was detected in 5 (3.6%) patients. Males had larger tumors (macroprolactinomas: 38, 71.7%) vs. 31 (36.9%), p <0.001; giant prolactinomas: 7 (13.2%) vs. 0 (0.0%), (p <0.001). Prolactinomas were graded as KNOSP-3 in 15 (11.5%), and KNOSP-4 in 20 (15.3%) patients. Primary indication was DA intolerance (59, 43.1%); males 14 (26.4%) vs. females 45 (53.6%), p = 0.006. Long-term remission (i.e., DA-free prolactin level <1xULN) was achieved in 87 (63.5%) patients, being higher in intended complete resection (69/92 [75.0%]), and lower in males (25 [47.2%] vs. 62 females [73.8%], p = 0.002). Transient DI (n = 29, 21.2%) was the most frequent complication.

CONCLUSIONS

Despite high proportions of macroprolactinoma and KNOSP 3-4, long-term remission rates were 63.5% overall, and 83.3% in microprolactinoma patients. Males had less favorable remission rate compared to females. These findings highlight that ETSS may be a safe and efficacious treatment to manage prolactinoma.

Exploring the prescribing trends and factors affecting initial anti-parkinsonian drug selection in Korea: A nationwide population-based cohort study

BACKGROUND

Parkinson's disease (PD) is a common neurodegenerative disorder typically treated with dopamine replacement therapy and dopamine agonists (DAs) to alleviate symptoms and minimize dyskinesia. Optimal treatment strategies for patients newly diagnosed with PD have been a topic of debate for many years.

METHODS

We conducted a 10-year descriptive study of drug prescription trends and factors affecting prescription choices for newly diagnosed drug-naïve PD patients using data from the National Health Insurance program in Korea. To identify statistically significant differences in yearly trends, we employed the Cochran-Armitage trend test. Additionally, we utilized multiple logistic regression analysis to investigate the factors associated with the selection of levodopa and DAs as initial anti-parkinsonian drugs.

RESULTS

A total of 99,118 patients with PD who were prescribed levodopa or DAs alone as initial anti-parkinsonian drugs between 2011 and 2020 were eligible for inclusion in the analysis. The prescription rate of DAs increased until 2012, and then steadily decreased annually. The likelihood of levodopa prescription increased with age and at higher-level hospitals. In terms of comorbidities, patients with Alzheimer's disease and cerebrovascular diseases were more likely to be prescribed levodopa than those with peptic ulcer disease and dyslipidemia.

CONCLUSION

The decline in levodopa prescriptions was reversed in 2012, and the prescription rate has continued to increase until recently. The odds ratio of levodopa prescription increased in elderly patients with Alzheimer's disease and decreased in patients with Medical aid insurance and peptic ulcer disease.

Surgical Treatment of Prolactinomas: Potential Role as a First-Line Treatment Modality

PURPOSE

Treatment with dopamine agonists (DAs) has been the first-line standard treatment for prolactinoma, and surgery has been reserved for drug intolerance and resistance for several decades. We evaluated whether surgery plays a primary role in prolactinoma management.

MATERIALS AND METHODS

We conducted a retrospective study of 210 prolactinoma patients who had received surgical treatment at our institution. We analyzed the treatment outcomes according to tumor extent, sex, and preoperative DA medication.

RESULTS

Overall hormonal remission was achieved in 164 patients (78.1%), and complete removal was achieved in 194 patients (92.4%). When the tumors were completely removed, the remission rate increased to 84.5%. Anterior pituitary function was normalized or improved in 94.6% of patients, whereas only 4.1% of patients showed worsening of hormone control. Hormonal remission was higher in patients who had not received DA preoperatively than in those who had received preoperative DA treatment. Smaller tumor size (<1 cm), no invasion into the cavernous sinus, and female sex were predictors of good surgical outcomes.

CONCLUSION

Although DAs remain the first-line standard treatment for prolactinomas, surgery can be an excellent option and should be considered as an alternative primary treatment modality when patients are predicted to achieve a good surgical outcome.

Effect of bromocriptine on glycemic control, risk of cardiovascular diseases and weight in patients with type 2 diabetes: a systematic review

BACKGROUND

Type 2 diabetes (T2DM) patients, including those in good glycemic control, have an increased risk of cardiovascular disease (CVD). Maintaining good glycemic control with drugs may reduce long-term CVD risk. Bromocriptine has been in clinical use for over 30 years, but the utility of bromocriptine in the treatment of diabetes patients has been proposed more recently.

OBJECTIVE

To summarize the available data regarding the effect of bromocriptine in T2DM management.

METHOD

A systematic literature search was conducted in the electronic databases, including Google Scholar, PubMed, Medline, and Science Direct, to locate studies that meet the objectives of this systematic review. Additional articles were included by conducting direct Google searches of the references cited by eligible articles located by the database search. The following search terms were used on PubMed "bromocriptine OR dopamine agonist AND diabetes mellitus OR hyperglycemia OR obese".

RESULT

Eight studies were included in the final analysis. 6210 of the 9391 study participants received bromocriptine treatment, while 3183 received a placebo. The studies demonstrated that patients who took bromocriptine treatment had significantly reduced blood glucose and BMI, which is the main cardiovascular risk factor in T2DM patients.

CONCLUSION

Based on this systematic review, bromocriptine may be used for T2DM treatment for its cardiovascular risk reduction effect, especially body weight reduction. However, advanced study designs might be warranted.

Dopamine agonist therapy in Parkinson's disease: Spanish expert consensus on its use in different clinical situations

BACKGROUND

Different types of therapies were proven effective for the medical management of motor and non-motor symptoms in Parkinson's disease (PD). We aimed to gain consensus on the Dopamine agonist (DA) therapy use in different clinical scenarios of Parkinson's disease (PD) patients.

METHODS

This consensus study was based on the nominal group technique. Initially, a Consensus Group comprising 12 expert neurologists in the PD field identified the topics to be addressed and elaborated different evidence-based preliminary statements. Next, a panel of 48 Spanish neurologists expressed their opinion on an internet-based systematic voting program. Finally, initial ideas were reviewed and rewritten according to panel contribution and were ranked by the Consensus group using a Likert-type scale. The analysis of data was carried out by using a combination of both qualitative and quantitative methods. The consensus was achieved if the statement reached ≥3,5 points on the voting process.

RESULTS

The Consensus Group produced 76 real-world recommendations. The topics addressed included 12 statements related to DA therapy in early PD, 20 statements concerning DA treatment strategy in patients with motor complications, 11 statements associated with DA drugs and their side effects, and 33 statements regarding DA therapy in specific clinical scenarios. The Consensus Group did not reach a consensus on 15 statements.

CONCLUSION

The findings from this consensus method represent an exploratory step to help clinicians and patients in the appropriate use of DA in different stages and clinical situations of PD.

Safety review of current pharmacotherapies for levodopa-treated patients with Parkinson's disease

INTRODUCTION

Levodopa remains the gold standard for treatment of Parkinson's disease (PD). Patients develop complications with disease progression, necessitating adjunctive therapy to control fluctuations in motor and non-motor symptoms and dyskinesia. Knowledge of medication safety and tolerability is critical to ascertain the benefit-risk ratio and select an adjunctive therapy that provides the highest chance for medication adherence. Posing a challenge are the sheer abundance of options, stemming from the development of several new drugs in recent years, as well as differences in commercial drug availability worldwide.

AREAS COVERED

This review evaluates the efficacy, safety, and tolerability of current US FDA-approved pharmacotherapies for levodopa-treated PD patients, including dopamine agonists, monoamine oxidase type-B inhibitors, catechol-O-methyltransferase inhibitors, the N-methyl-D-aspartate receptor antagonist amantadine, and the adenosine receptor antagonist istradefylline. Data were taken from pivotal phase III randomized controlled and post-surveillance studies, when available, that directly led to FDA-approval.

EXPERT OPINION

No strong evidence exists to support use of a specific adjunctive treatment for improving Off time. Only one medication has demonstrated improvement in dyskinesia in levodopa-treated PD patients; however, every patient cannot tolerate it and therefore adjunctive therapy should be tailored to an individual's symptoms and risk for specific adverse effects.

Role of Immediate Postoperative Prolactin Measurement in Female Prolactinoma Patients: Predicting Long-Term Remission After Complete Tumor Removal

BACKGROUND

Transsphenoidal surgery is one of the important treatment options in the management of prolactinomas; however, complete resection of the tumor does not always lead to endocrinological remission. While many studies have investigated preoperative factors associated with surgical outcome, little has been known about the relationship between postoperative factors and long-term surgical outcomes; moreover, there is no consistency in results. The aim of this study was to demonstrate the reliability of immediate postoperative prolactin levels as predictors of long-term outcomes.

METHODS

A total of 105 female patients who underwent complete removal of their histologically confirmed prolactinomas were included, and their medical records were retrospectively reviewed. To evaluate the predictability of immediate postoperative prolactin levels for long-term remission, prolactin levels were measured at 2, 6, 12, 18, 24, 48, and 72 h after surgery.

RESULTS

From the 105 included patients, 95 (90.5%) and 10 (9.5%) belonged to the remission and non-remission groups, respectively. A significant difference was observed in the prolactin level measured 6 h after surgery between the remission and non-remission groups, and this difference stayed apparent until 72 h after surgery. We derived a cut-off value for every postoperative time point that showed a significant relationship with disease remission.

CONCLUSION

Our study suggests that immediate postoperative measurement of prolactin levels is a reliable predictor of long-term remission and can contribute to early identification of patients who require adjuvant treatment after surgery.

Dopamine agonists versus levodopa monotherapy in early Parkinson's disease for the potential risks of motor complications: A network meta-analysis

BACKGROUND

Compared with levodopa, dopamine agonists (DAs) as initial treatment are associated with lower incidences of motor complications in early Parkinson's disease (PD). There is no strong evidence that a given DA is more potent in lower incidences of motor complications than another.

OBJECTIVE

We performed a network meta-analysis of levodopa versus DAs as monotherapy in early PD to access the risk of motor complications.

METHODS

Databases were searched up to June 2022 for eligible RCTs. Levodopa and four DAs (pramipexole, ropinirole, bromocriptine and pergolide) were investigated. The incidences of motor complications and efficacy, tolerability and safety outcomes were analyzed.

RESULTS

Nine RCTs (2112 patients) were included in the current study. The surface under the cumulative ranking curve (SUCRA) indicated that levodopa ranked first in the incidence of dyskinesia (0.988), followed by pergolide, pramipexole, ropinirole, and bromocriptine (0.704, 0.408, 0.240, 0.160). Pramipexole was least prone to wearing-off (0.109) and on-off fluctuation (0.041). Levodopa performed best in improvements of UPDRS-II, UPDRS-III, and UPDRS-II + III (0.925, 0.952, 0.934). Bromocriptine ranked first in total withdrawals and withdrawals due to adverse events (0.736, 0.751). Four DAs showed different adverse events profiles.

CONCLUSION

In the two non-ergot DAs, ropinirole is associated with a lower risk of dyskinesia while pramipexole is associated with lower risks of wearing-off and on-off fluctuations. Our research may facilitate head-to-head research, larger sample sizes, long following-up time RCTs to confirm the findings of this network meta-analysis.

How to manage intolerance to dopamine agonist in patients with prolactinoma

PURPOSE

Dopamine agonists (DA) are the gold-standard for prolactinoma and hyperprolactinemia treatment. Intolerance to DA leading to drug drop out occurs in 3 to 12% of cases. We provide here a review of published data about DA intolerance and present a case report concerning the use of intravaginal cabergoline.

METHODS

We review the literature on the definition, the pathogenesis, frequency and management of DA intolerance. In addition, the review provides strategies to enhance tolerability and avoid precocious clinical treatment withdrawal.

RESULTS

Cabergoline is often cited as the most tolerable DA and its side effects tend to ameliorate within days to weeks. Restarting the same drug at a lower dose or switching to another DA can be used in cases of intolerance. The vaginal route can be tried specifically if there are gastrointestinal side effects in the oral administration. Symptomatic treatment could be attempted, although mainly based on a strategy used in other diseases.

CONCLUSIONS

Due to limited data, no guidelines have been developed for the management of intolerance in DA treatment. The most frequent management is to perform transsphenoidal surgery. Nevertheless, this manuscript provides data derived from published literature and expert opinion, suggesting new approaches to this clinical issue.

The effect of levodopa treatment on vascular endothelial function in Parkinson's disease

OBJECTIVE

There has been increasing awareness that micro-vascular alteration or vascular inflammation has been associated with levodopa-induced dyskinesia in PD. Vascular endothelial function assessed by flow mediated dilation (FMD) is known to reflect early microvascular change. We compare the impact of levodopa or dopamine agonist treatment on the change of FMD in de novo PD patients.

METHODS

This retrospective study used a selected sample from registry. We identified de-novo PD patients who underwent FMD at baseline, and follow-up FMD after 1 year (± 2 month) of levodopa (n = 18) or dopamine agonist (n = 18) treatment.

RESULTS

FMD decreased after levodopa (8.60 ± 0.46 to 7.21 ± 0.4, p = 0.002) but there were no significant changes after DA treatment (8.33 ± 0.38 to 8.22 ± 0.33, p = 0.26). Homocysteine rose (11.52 ± 0.45 to 14.33 ± 0.68, p < 0.05) during levodopa treatment, but dopamine agonist had no effect (10.59 ± 0.38 to 11.38 ± 0.67, p = 0.184). Correlation analysis revealed that the changes in homocysteine level had non-significant correlation with FMD change (r =  - 0.30, p = 0.06). FMD change was not associated with age (p = 0.47), disease duration (p = 0.81), baseline motor UPDRS (p = 0.43), motor UPDRS change (p = 0.64), levodopa equivalent dose change (p = 0.65).

CONCLUSIONS

We found that 1-year levodopa treatment may adversely affect vascular endothelial function in de novo PD. Further studies are needed to clarify the exact pathogenesis and clinical implication of levodopa-induced endothelial dysfunction in PD.

DRD2 expression based on 18F-fallypride PET/MR predicts the dopamine agonist resistance of prolactinomas: a pilot study

PURPOSE

The dopamine agonists (DA) have been used widely to treat prolactinomas. However, it is difficult to predict whether the patient will be responsive to DA treatment.

METHODS

We aimed to investigate whether the in vivo expression of DRD2 based on ¹⁸F-fallypride PET/MR could predict the therapeutic effect of DA on prolactinomas. Seven patients with prolactinomas completed ¹⁸F-fallypride PET/MR. Among them, three patients underwent surgery and further tumor immunohistochemistry. Imaging findings and immunohistochemical staining were compared with treatment outcomes.

RESULTS

¹⁸F-fallypride PET/MR was visually positive in 7 of 7 patients, and DRD2 target specificity could be confirmed by immunohistochemical staining. A significantly lower tracer standard uptake value (SUV) could be detected in the resistant patients (n = 3) than in the sensitive patients (n = 4; SUV_mean, 4.67 ± 1.32 vs. 13.57 ± 2.42, p < 0.05). DRD2 expression determined by ¹⁸F-fallypride PET/MR corresponded with the DA treatment response.

CONCLUSION

¹⁸F-fallypride PET/MR may be a promising technique for predicting DA response in patients with prolactinoma.

Distinctive Effects of D1 and D2 Receptor Agonists on Cortico-Basal Ganglia Oscillations in a Rodent Model of L-DOPA-Induced Dyskinesia

L-DOPA-induced dyskinesia (LID) in Parkinson's disease has been linked to oscillatory neuronal activities in the cortico-basal ganglia network. We set out to examine the pattern of cortico-basal ganglia oscillations induced by selective agonists of D1 and D2 receptors in a rat model of LID. Local field potentials were recorded in freely moving rats using large-scale electrodes targeting three motor cortical regions, dorsomedial and dorsolateral striatum, external globus pallidus, and substantial nigra pars reticulata. Abnormal involuntary movements were elicited by the D1 agonist SKF82958 or the D2 agonist sumanirole, while overall motor activity was quantified using video analysis (DeepLabCut). Both SKF82958 and sumanirole induced dyskinesia, although with significant differences in temporal course, overall severity, and body distribution. The D1 agonist induced prominent narrowband oscillations in the high gamma range (70-110 Hz) in all recorded structures except for the nigra reticulata. Additionally, the D1 agonist induced strong functional connectivity between the recorded structures and the phase analysis revealed that the primary motor cortex (forelimb area) was leading a supplementary motor area and striatum. Following treatment with the D2 agonist, narrowband gamma oscillations were detected only in forelimb motor cortex and dorsolateral striatum, while prominent oscillations in the theta band occurred in the globus pallidus and nigra reticulata. Our results reveal that the dyskinetic effects of D1 and D2 receptor agonists are associated with distinct patterns of cortico-basal ganglia oscillations, suggesting a recruitment of partially distinct networks.

Brain monoamine vesicular transport disease caused by homozygous SLC18A2 variants: A study in 42 affected individuals

PURPOSE

Brain monoamine vesicular transport disease is an infantile-onset movement disorder that mimics cerebral palsy. In 2013, the homozygous SLC18A2 variant, p.Pro387Leu, was first reported as a cause of this rare disorder, and dopamine agonists were efficient for treating affected individuals from a single large family. To date, only 6 variants have been reported. In this study, we evaluated genotype-phenotype correlations in individuals with biallelic SLC18A2 variants.

METHODS

A total of 42 affected individuals with homozygous SLC18A2 variant alleles were identified. We evaluated genotype-phenotype correlations and the missense variants in the affected individuals based on the structural modeling of rat VMAT2 encoded by Slc18a2, with cytoplasm- and lumen-facing conformations. A Caenorhabditis elegans model was created for functional studies.

RESULTS

A total of 19 homozygous SLC18A2 variants, including 3 recurrent variants, were identified using exome sequencing. The affected individuals typically showed global developmental delay, hypotonia, dystonia, oculogyric crisis, and autonomic nervous system involvement (temperature dysregulation/sweating, hypersalivation, and gastrointestinal dysmotility). Among the 58 affected individuals described to date, 16 (28%) died before the age of 13 years. Of the 17 patients with p.Pro237His, 9 died, whereas all 14 patients with p.Pro387Leu survived. Although a dopamine agonist mildly improved the disease symptoms in 18 of 21 patients (86%), some affected individuals with p.Ile43Phe and p.Pro387Leu showed milder phenotypes and presented prolonged survival even without treatment. The C. elegans model showed behavioral abnormalities.

CONCLUSION

These data expand the phenotypic and genotypic spectra of SLC18A2-related disorders.

Dopamine agonist monotherapy utilization in patients with Parkinson's disease

Objectives

To characterize patients with Parkinson's disease (PD) who initiated dopamine agonist (DA) monotherapy, describe medication utilization and provider types, and estimate medication adherence and discontinuation rates.

Methods

Retrospective study identified patients with PD in the Optum Research Database and included those with ≥1 claim for DA or levodopa between 09/01/2012 and 12/31/2018, ≥2 PD diagnoses, commercial or Medicare Advantage Part D (MAPD) insurance, ≥40 years old, and continuous medical and pharmacy coverage ≥12 months before and after index date. A subset of patients receiving DA monotherapy was selected for this analysis. Variables were analyzed descriptively. Adherence was measured with medication possession ratio (MPR) and proportion of days covered (PDC); defined as ≥0.80.

Results

Patients (N = 642) had mean (SD) age of 70.2 (9.9) years, 70.6 % had MAPD coverage, and 61.7 % were male. Neurologists prescribed 64.6 % of DA monotherapy, and 56.9 % of patients had ≥2 PD diagnoses before or on the index date. Index therapy was discontinued by 44.1 % of patients, and 55.9 % persisted for 12 months without change. Mean (SD) time to discontinuation was 102 (79) days. Mean (SD) MPR for patients (n = 562) with ≥2 fills was 0.84 (0.2); 70.3 % were MPR adherent. Mean (SD) PDC for all 642 patients was 0.66 (0.3); 50.5 % were PDC adherent.

Conclusion

Adherence and continuation of therapy were suboptimal, which could translate into poor patient outcomes. Future studies could provide insights on the impact of low adherence and persistence with DA monotherapy.