Rare Abdominal Manifestations in a Patient with Parkinson’s Disease after Deep Brain Stimulation of the Subthalamic Nucleus: A Case Report

Abstract

Introduction

Abdominal pain is an occasionally observed non-motor symptom during “off” periods in Parkinson’s disease (PD), often associated with end-of-dose wearing-off (EODWO). However, severe abdominal manifestations such as painful abdominal contraction (PAC) are rare, and their pathogenesis remains unclear. We report a unique case in which both PAC and belly dancer’s dyskinesia (BDD) emerged following subthalamic nucleus deep brain stimulation (STN-DBS).

Case Presentation

A 74-year-old woman with PD underwent bilateral STN-DBS. Following a postoperative reduction in her levodopa dosage, she developed continuous abdominal pain with a downward-pulling sensation, which was diagnosed as PAC. Symptoms worsened in upright positions and improved supine. With an increase in STN-DBS stimulation intensity, she subsequently developed wave-like involuntary contractions of the abdominal wall muscles, consistent with BDD, while her PAC remained unchanged. STN-DBS adjustments and dopaminergic agents other than levodopa provided only partial relief, with PAC showing minimal improvement. Restoration of the preoperative levodopa dosage led to marked alleviation of PAC. Additional STN stimulation effectively managed recurrent EODWO-related pain. Four months postoperatively, motor symptoms improved significantly, with only mild peak-dose BDD remaining.

Conclusion

This case illustrates that PAC may result from reduced baseline dopamine levels and may not respond to STN-DBS alone. The co-occurrence of PAC and BDD suggests a complex interplay between motor and non-motor circuits, possibly involving spinal plasticity and central pattern generators. Clinicians should consider that some cases of severe abdominal pain in PD may represent distinct non-motor phenomena that appear to respond preferentially to levodopa administration.

Introduction

Abdominal pain is recognized as a non-motor symptom associated with the wearing-off phase in patients with Parkinson’s disease (PD), potentially serving as an early indicator of end-of-dose wearing-off (EODWO) [1]. The prevalence of abdominal pain originating from the rectus abdominis has been reported in 3.7% of patients with PD [2]. Painful abdominal contraction (PAC) is characterized by a forceful downward-pulling sensation accompanied by abdominal discomfort and severe cramping without accompanying nausea or vomiting [1, 3, 4]. Conversely, repetitive and dyskinetic involuntary movements of the anterior abdominal wall are referred to as belly dancer’s dyskinesia (BDD). Although the precise pathogenesis of PAC and BDD remains unclear, we report a rare case in which both conditions occurred in a single patient following deep brain stimulation (DBS) surgery targeting the subthalamic nucleus (STN).

Case Report

A 74-year-old woman with PD, Hoehn and Yahr stage 3, was referred to our hospital for DBS surgery. Her medical history included a left femoral neck fracture, and she had incomplete peroneal nerve paralysis in her left leg due to inappropriate posture at the surgery of the femur. There was no notable family history. She has experienced bradykinesia for the past 7 years. On admission, clinical examination revealed tremors in her left leg, left-predominant rigidity and bradykinesia, freezing of gait, postural instability, and moderate abdominal dull pain during the off period as a consequence of EODWO. Additionally, she exhibited occasional mild peak-dose dyskinesia involving slow trunk movements and mild camptocormia. Her medical regimen included levodopa 400 mg with benserazide 100 mg (divided into four doses), selegiline hydrochloride 5 mg, and zonisamide 50 mg. Her Unified Parkinson’s Disease Rating Scale (UPDRS) Part Ⅲ scores were 14 in the on state and 36 in the off state. Bilateral STN-DBS was performed without complications, as confirmed by postoperative computed tomography (CT). Vercise Cartesia^™ directional electrodes were implanted as part of a Vercise^™ PC DBS system (Boston Scientific, Marlborough, MA, USA). Electrode placements targeted the posterolateral STN and were verified intraoperatively via microelectrode recordings and postoperatively through CT-MRI fusion imaging. The same medication regimen was resumed the day after surgery, during which the patient continued to benefit from the microlesion effects. Six days post-surgery, her medications were adjusted to levodopa 200 mg with benserazide 50 mg (four doses), rasagiline mesylate 1 mg, and zonisamide 50 mg before starting the stimulation. The following day, she experienced a continuous heavy downward-pulling sensation with dull abdominal pain, preventing her from standing. The pain was localized to the abdominal wall, without any visceral component. She did not exhibit tremors, bradykinesia, or rigidity in her extremities. Abdominal CT and blood tests revealed no abnormalities. She could still stand and walk a few meters. Suspecting abdominal off-dystonia akin to a super-off state, the STN-DBS was started and gradually increased to 0.8 mA and 1.0 mA on the left and right sides, respectively. Despite these adjustments, the abdominal pain persisted, which was later diagnosed as PAC. She then developed sudden, continuous, wave-like involuntary contractions of the anterior abdominal wall muscles, indicative of BDD occurring concurrently with PAC [5]. The intense and continuous abdominal movements caused fatigue. Dyskinesia was confined to the abdominal region, with no involvement of the trunk or extremities (online suppl. Video 1; for all online suppl. material, see https://doi.org/10.1159/000550603). Both BDD and PAC worsened in sitting and standing positions but were alleviated in the supine position. Although the onset was abrupt, the movements were consistent across various contexts other than the supine position and did not fluctuate with attention or suggestion. There were no other features indicative of a functional movement disorder. As increased stimulation failed to relieve her symptoms, the STN-DBS was turned off, and a 4.5-mg rotigotine patch was applied. This intervention resolved BDD but had no effect on PAC. Subsequent trials of entacapone 200 mg and ropinirole hydrochloride patch 8 mg/day were also ineffective. Ultimately, her levodopa gradually increased to the preoperative level, which addressed PAC. After the microlesion effect, moderate abdominal pain caused by EODWO recurred but was effectively managed by additional stimulation of the STN at 130 Hz, 60 μs with 0.4 mA on the left and 0.2 mA on the right. The patient’s gait and postural stability improved. Four months postoperatively, her UPDRS Part III score was reduced to 3. Abdominal pain, including PAC, was not observed, and the patient occasionally experienced mild BDD at her peak levodopa dose, but this was not problematic for her. This indicates that BDD represented a type of levodopa-induced dyskinesia, manifesting independently of PAC. At 4 years postoperatively, increasing stimulation currents elicited BDD (online supplementary Video 2), while her symptoms remained stable at Hoehn and Yahr stage 3.

Discussion

In this case, PAC appeared after the patient’s levodopa dose was reduced, continued throughout the day, and improved when the dose was restored. This clinical course indicates that a decrease in baseline serum dopamine levels may cause PAC. To our knowledge, only three studies have described an association between PAC and PD (Table 1). Gee et al. [4] reported that DBS was ineffective in treating abdominal pain, which responded only to levodopa administration, similar to our findings. STN-DBS, despite its recognized effectiveness in addressing off dystonia, has been reported to be ineffective in cases of PAC. Furthermore, our patient exhibited both PAC and BDD simultaneously, suggesting that PAC is not merely a super-off motor state, but an independent manifestation of, potentially, pain. Dopamine depletion has been implicated in the development of non-motor Parkinsonian symptoms, including pain, likely through dysfunction of non-motor circuits, such as the mesolimbic pathway, which comprises dopaminergic neurons. The dopaminergic descending pathway originating from A11 dopaminergic neurons in the posterior hypothalamus exerts antinociceptive effects via D2-like receptors in the spinal cord’s substantia gelatinosa neurons. Disruption of this pathway may contribute to pain in patients with PD [6]. Although several etiologies for BDD have been proposed, including drug-induced onset, postoperative changes, functional movement disorders, and spinal cord tumors [6], this is the first reported case of BDD as an adverse event following STN-DBS.

Table 1.

Summary of 6 patients of PD presenting with PAC

Study (year)	Age, years	Sex	Effective treatment	Exacerbating factor	Improving factor
Kataoka et al. [1] (2012)	80	F	Increase LEDD	Sitting, walking	Supine position
Kataoka et al. [1] (2012)	77	M	Increase LEDD	Sitting, walking	Supine position
Rana et al. [3] (2011)	61	M	Administration of levodopa	N.A.	N.A.
Rana et al. [3] (2011)	71	M	Administration of levodopa	N.A.	N.A.
Gee et al. [4] (2015)	N.A.	N.A.	Administration of levodopa (DBS not effective)	N.A.	N.A.
Present case	74	F	Administration of levodopa (DBS not effective)	Sitting, walking	Supine position

F, female; M, male; N.A., not available; LEDD, levodopa equivalent daily dose; DBS, deep brain stimulation.

This raises the question of why these symptoms are localized to the abdominal region. Chronic pain induces plastic and structural changes in the spinal cord. Recent studies have reported microglial accumulation in the dorsal and ventral horns during chronic pain states, leading to hyperactivation of dorsal root ganglion and ventral horn neurons [7]. In our patient, chronic abdominal pain due to EODWO may have induced these types of abnormal hyperactivities in her spinal cord, resulting in the emergence of PAC and BDD. Tamburin et al. [8] indicated that BDD may originate from abnormalities in the spinal central pattern generator. It is hypothesized that STN-DBS may influence the most sensitive spinal central pattern generator via the mesencephalic locomotor region, although this remains to be verified. Clinicians should be aware that severe abdominal symptoms, exemplified by PAC, may represent a discrete non-motor phenotype in PD, showing preferential responsiveness to levodopa over other dopaminergic agents and STN-DBS. Interestingly, 4 years after surgery, BDD was less severe and involved somewhat different movements compared with onset. Although the underlying mechanism remains uncertain, the patient’s abdominal pain had completely resolved following discharge from surgery. This clinical course raises the possibility that reduced nociceptive input may have induced plasticity changes at the spinal cord level, which in turn could have attenuated motor hyperexcitability. Variability in how such plasticity develops within the spinal cord might, at least in part, account for the altered movement patterns observed.

Stimulation of contacts dorsal to STN has been associated with engagement of the pallidothalamic tract, resulting in suppression of stimulation-induced dyskinesia while maintaining motor benefits in patients with PD [9]. Alternatively, globus pallidus internus stimulation has shown direct anti-dyskinetic effects, even in cases where dyskinesias persist despite dopaminergic medication reduction, and may be preferable in patients with refractory or atypical dyskinesias when STN programming proves insufficient [10]. The efficacy of stimulation strategies such as pallidothalamic tract engagement via STN-DBS or globus pallidus internus-DBS for rare abdominal symptoms like BDD and PAC remain unclear, highlighting the need for further investigation to determine their therapeutic relevance in these manifestations.

Acknowledgments

We gratefully acknowledge the support of our movement disorders team.

Statement of Ethics

The use of clinical data was approved by the Ethical Committee of Tokushima University Hospital (No. 3743-4). Written informed consent was obtained from the patient according to the Declaration of Helsinki. The CARE Checklist has been completed by the authors for this case report, attached as online supplementary material.

Conflict of Interest Statement

The authors have no conflicts of interest to declare.

Funding Sources

This work was supported by JSPS KAKENHI Grants 23K08523 and Beauty Life Corporation.

Author Contributions

Conceptualization: R.M. Data curation and visualization: H.K., R.M., and K.M. Methodology: HK, R.M., K.M., T.M., J.F., and K.S. Project administration: R.M., Y.N., and Y.T. Writing – original draft: H.K. and R.M. Writing – review and editing: H.K., R.M., K.M., T.M., J.F., K.S., Y.N., and Y.T.

Funding Statement

This work was supported by JSPS KAKENHI Grants 23K08523 and Beauty Life Corporation.

Data Availability Statement

The data supporting the findings of this case report are not publicly available due to privacy and ethical restrictions. De-identified data may be made available from the corresponding author upon reasonable request and with approval from the Institutional Ethics Committee.