Dear Editor,
A sigmoid volvulus (SV) is a twisting of the sigmoid colon resulting in the obstruction of the colon [
1]. Since the colon is a gastrointestinal system frequently loaded with alpha-synuclein (aSyn) in Parkinson’s disease (PD), the role of aSyn in the pathogenesis of SV is of interest. However, although SV was reported in some patients with PD, pathologic reports were rarely made, leaving the role of aSyn in SV undetermined [
2-
4]. Herein, we report two cases of SV in PD patients with pathologic studies.
The first patient is a 67-year-old gentleman. At the age of 66, he presented with festination without a fall. Neurological examination showed limb bradykinesia and rigidity, which were worse on the left. Resting tremor and postural instability were absent (Hoehn and Yahr stage 2). Brain magnetic resonance imaging (MRI) was unremarkable, and positron emission tomography (PET) using
18F-N-3-fluoropropyl-2β-carbon ethoxy-3β-4-iodophenyl nortropane (FP-CIT) showed bilaterally decreased uptake of FP-CIT. Dopaminergic medications were effective. He had a history of lingering constipation and two episodes of SV after the diagnosis of PD (
Figure 1A). He underwent elective sigmoidectomy because of recurrent attacks. Pathologic examination showed unremarkable findings with negative aSyn aggregation and the absence of infiltrating lymphocytes (CD4, CD8) (
Figure 1B).
The second patient was an 85-year-old gentleman. He was diagnosed with PD at the age of 81. He had bilateral postural tremor, bilateral limb bradykinesia (worse in the left limb), and mild postural instability (Hoehn and Yahr stage 2.5). Brain MRI showed mild periventricular white matter change and mild cortical atrophy. 18F-FP-CIT PET showed decreased uptake of 18F-FP-CIT in the bilateral striata. His parkinsonism was relieved by dopaminergic medications. He had a history of drug-resistant constipation. At the age of 85, he visited the emergency room because of severe abdominal pain, where the diagnosis of SV was made. As endoscopic decompression failed, sigmoidectomy was performed. The removed sigmoid was unremarkable in pathologic examination, including negative immunostaining of aSyn and CD4/CD8.
The clinical and radiologic features of the two patients were compatible with PD. The two patients had suffered from SV three and four years after PD diagnosis, respectively. Since pathologic examination of the sigmoid was unremarkable with the absence of aSyn inclusions and no infiltrating leukocytes, the contribution of aSyn or inflammatory change to SV is uncertain in our cases. Previously, only one study reported eosinophilic hyaline inclusions suggesting Lewy bodies in a PD patient complicated by SV [
5]. However, immunostaining was not performed, and inclusions were rarely detected in the submucosal plexus in the rectum in the second pathologic examination, while the initial pathologic examination of the sigmoid at the time of SV showed no inclusions.
The exact incidence of SV in PD is not known, although a few studies have highlighted the possible association between SV and PD. In a large series, there were 7 PD patients out of 1,030 SV cases (0.7%), data which was collected in an endemic area (the “volvulus belt”) [
6]. SV was estimated to develop more frequently in PD than in the general population in Edinburg, UK [
2].
Constipation is one of the important risks of SV, and many PD patients have treatment-resistant constipation, similar to our patients. Moreover, dopaminergic medications can aggravate constipation. Thus, a higher frequency of SV could be expected in PD. However, the absence of aSyn in the colon of our patients is contradictory to the pathological correlation between PD and SV. In fact, aSyn inclusions in the gastrointestinal tract, including the colon, are also common in healthy controls [
7], and only the inclusions in the caudal portion of the tract demonstrated statistical significance. Moreover, recent studies introduced a dichotomous view on the pathogenesis of PD (“brain-first” versus “body-first”), challenging the role of aSyn in the enteric nervous system, especially in the brain-first subtype of PD.
In conclusion, the correlation between SV and aSyn inclusion is questionable in our patients. However, since there were only two PD cases with SV, further studies are needed with a larger number of cases to substantiate the findings of this study.