Intraspinal Sparganum mansoni infection with the extraction of a live adult worm

PRACTICAL IMPLICATIONS

Consider intraspinal sparganosis in the differential diagnosis of patients with recent travel to Southeast Asia, and with imaging findings consistent with nodular, circular, or mass-like lesions in the spinal canal.

A 54-year-old man was hospitalized with a 7-month history of progressive hip numbness and pain radiating to both legs. Numbness and pain occurred first in the left hip and leg, and gradually extended to the right. At first, the pain was slight and could be alleviated by rest but rapidly progressed to persistent burning pain. Immediately before presentation, the patient became incontinent to urine and stool. The patient came from a rural area and provided no significant medical history.

The patient complained of a sensations of numbness and burning pain of both hips and legs, which was aggravated by hip flexion. Paresthesia was found in the saddle area. No abnormalities of strength, muscle tone, or reflexes were detected.

MRI of the whole spine showed multiple circular and nodular mass-like, heterogeneously enhancing lesions most prominently observed at T12-S2, involving the conus medullaris and cauda equina (figure 1, A–D). Based on these findings, intraspinal tumors were first suspected, and an exploratory operation was performed. Severe tissue adhesion and edema were found in the intradural space. A small (7 cm × 0.2 cm) white worm was discovered among the rootlets of the cauda equina, which was initially mistaken for a nerve until wriggling was observed (figure 1E and video 1). The longitudinal, pseudosegmented, thread-like helminth was carefully isolated surgically and identified as Sparganum mansoni by histology (video 2). The diagnosis of intraspinal sparganosis was revised by pathologic findings.

Figure 1. MRI of the lumbar spine.

MRI of the lumbar spine shows multiple circular and mass-like lesions with hypointense and isointense on T1WI (A), hyperintense on T2WI (B), and fat-suppression T2WI (C). The lesions exhibited heterogeneous enhancement after contrast administration (D). A tapeworm isolated from the surgery and was observed to be wriggling in the saline (E).

Video 1

The tapeworm just isolated from the surgery was observed to be wriggling in the saline.Download Supplementary Video 1 ^{(47.2MB, mov)} via http://dx.doi.org/10.1212/000658_Video_1

Video 2

The tapeworm was wriggling in saline in a specimen bag, which was identified as S. mansoni by histology.Download Supplementary Video 1 ^{(33.8MB, mov)} via http://dx.doi.org/10.1212/000658_Video_2

Furthermore, blood and CSF were both positive for S. mansoni antibody when analyzed by ELISA. A subsequent MRI of the brain revealed a mass-like lesion in the left cerebellopontine angle, which was hypointense on T1WI and hyperintense on T2WI, and heterogeneously enhancing after contrast administration (figure 2).

Figure 2. MRI of the brain.

MRI of the brain shows a mass-like lesion in the left cerebellopontine angle, with hypointense on T1WI (A and E) and hyperintense on T2WI (B), and heterogeneous signal intensity in the enhanced sequence (D and F). Sagittal view of the brain shows a tunnel-like cavity within the lesion, which typically indicates the migration of a parasite (E).

The patient was treated postoperatively with praziquantel at the recommended dose of 120 mg/kg, divided into 3 doses per day for 2 days. At the 4-month follow-up, the patient reported only mild pain in the hip without incontinence.

Discussion

Sparganosis is an uncommon parasitic infection caused by plerocercoid larvae or Diphyllobothrium of the genus Spirometra. Intraspinal sparganosis is extremely rare.¹ Of the more than 1600 cases of sparganosis that have been reported worldwide, only 13 were of spinal sparganosis.¹ Humans occasionally become intermediate hosts for S. mansoni. Infection may occur by ingesting undercooked infected meat,^2,3 drinking contaminated water, or applying raw flesh as traditional poultices.⁴ The incidence of sparganosis is much higher in Southeast Asian such as China, Korea, and Japan due to the high consumption of raw frog and snake meat in the region.² In our case, the patient denied eating raw or undercooked frog or snake meat, or using raw flesh as a therapeutic poultice, but whether the patient obtained the infection from contaminated water was unclear.

The imaging profile of sparganosis is nonspecific. Local “beadlike” or conglomerated ring-like enhancement and serpiginous tunneling have been reported to be characteristic.⁵ Other features, such as heterogeneously enhancing mass-like or circle-like lesions, are also frequently indicative of tumors.^1,4 In our case, both circle-like and mass-like lesions were observed in the MRI scan of the spine, leading to a high suspicion for intraspinal tumors until the live worm was discovered intraoperatively. Considering the literature that we reviewed, this report is the first to extract a live adult S. mansoni from a patient's spinal canal. Whether surgical removal or praziquantel treatment should be carried out remains under debate.^5,6 Our case demonstrated that surgical removal of the live worm yields a favorable prognosis.

Notably, except for the lesion in the spinal canal, a mass-like heterogeneously enhancing lesion was found in the left cerebellopontine angle in the brain. The sagittal view of the MRI scan showed a tunnel-like cavity lesion (figure 2E), which indicates that the S. mansoni might migrate between the brain and the spinal canal through the ventricular system or through loose connective tissue around the nerve fibers.⁷ Dual infection of spinal sparganosis and racemose neurocysticercosis was reported by Chotmongkol et al.⁶ in 2018. Considering all factors, cerebral sparganosis was suspected in our patient. Because of the lack of symptoms and cranial nerve abnormalities, the patient refused an exploratory operation. The patient received treatment with praziquantel, and a follow-up visit was recommended.

Currently, our case is the 6th report of intraspinal sparganosis worldwide. Although rare, this case emphasizes the need to consider intraspinal sparganosis as the differentiation diagnosis of patients with heterogeneously enhanced lesions in the spinal canal, especially for those who live in or travel from Southeast Asia.

Appendix. Authors

Study funding

This work was supported by grants from Omics-Based Precision Medicine of Epilepsy entrusted by the Key Research Project of the Ministry of Science and Technology of China (Grant No. 2016YFC0904400) and the National Natural Science Foundation of China (Grant nos. 81771407 and 81701182).

Disclosure

The authors report no disclosures relevant to the manuscript. Full disclosure form information provided by the authors is available with the full text of this article at Neurology.org/cp.