Sparganosis is an uncommon disease in humans. It is caused by larvae of the tapeworm genus Spirometra
, whose definitive hosts are domestic and wild cats and dogs1,6,11)
. The disease usually involves the subcutaneous tissue or muscle of the chest, abdominal wall, or limbs. Central nervous system involvement is relatively rare, with infection of the spinal system being extremely rare2,3)
. To date, only nine cases have been reported; in all but one patient, the worm was surgically removed and identified1,9)
Sparganosis occurs more frequently in eastern Asia than in other areas of the world. In this region, human infection develops accidentally by drinking water contaminated with infected copepods, ingesting raw or inadequately cooked snakes or frogs infected with the sparganum, or by applying the flesh of an infected intermediate host as a poultice to the eye or an open wound4,9)
The first male patient had a history of ingestion of inadequately cooked snakes and frogs 40 years ago and had 2 year-history of clinical manifestation. The second female patient ate inadequately cooked snakes 10 years ago, but her symptoms emerged 7 days after a recent rauma.
Considering the ingestion history and life span of sparganum in humans; 5-20 years, we concluded that the worm found in the woman was more likely to be alive and histological findings also supported such a possibility. Her acute manifestation of pain seemed to be related with a inflammatory immune reaction. In contrast, the male patient ate inadequately cooked snakes and frogs 40 years ago, which implies much longer duration than the mean life span of sparganum. In addition, histological confirmation of the dead worm led us to conclude that further surgical attempts for total removal would be ineffective for him2). After visiting another hospital, however, he underwent the second operation at that hospital, which resulted in aggravation of neurological deficit and pain. We presumed that it might have been further attempted to reduce severe adhesion between cauda equina and granulation tissue which only caused further worsening of pain and neurologic deficts.
Preoperative diagnosis of cerebral sparganosis mansoni, based on clinical and radiological findings, is difficult8)
. Preoperative diagnosis is rare in human sparganosis, because the condition is very uncommon even in endemic areas. Diagnosis has usually been made after surgical removal of worms2,4,8,10,12)
. The presence of anti-sparganum antibody in CSF or serum, measured by ELISA, is highly sensitive and specific in the diagnosis of sparganosis4,7,9)
. However, because it is difficult to suspect this parasitic disease based on clinical and imaging findings, the value of ELISA in preoperative diagnosis is limited.
In the female patient described here, we attempted surgical resection with preoperative wrong diagnosis, and without a preoperative ELISA test. The goals of our surgery were to remove the offending lesion and to confirm a correct diagnosis. Fortunately, the worm was located in the epidural space only without severe inflammation, and thus detachment from the dura was easily performed. For this reason, total mass removal was easily done and the outcome was excellent without correct preoperative diagnosis. In the male patient, we also did not suspect parasite infection and tried to get a tissue for histological diagnosis. Preoperative image indicated that total removal of mass would be very difficult but we were only able to obtain a small quantity of granulation tissue, because of severe arachnoiditis and adhesion. If we had suspected parasite infection and done ELISA test preoperatively, we would have avoided such an inefficacious intradural surgery for biopsy, considering surgical risk, life span of sparganum and the ingesting history of raw foods. His poor neurological function did not improve and became worse than his preoperative state. His poor outcome seems to be resulted from the severe adhesion between cauda equina and granulation tissue, the long duration of his urinary and defecation problem, and the irritation of adhesive cauda equina induced by surgery. The granulation tissue of sparganum is reported to regress slowly after death of worm2)
. If preoperative correct diagnosis had been made with ELISA, conservative management on this male patient would have been a better choice.
Considering our two cases, we conclude that preoperative ELISA can be helpful for correct diagnosis and treatment of the indistinct spinal mass, especially in endemic areas. In addition, though surgical removal of worm and inflammatory granulation usually has a good prognosis, the attempt to remove the dead worm and adhesive granulation tissue may be the worst option to the patient like our case. With a single imaging study, it is difficult to determine whether the worm is alive1,2)
. However, the differences of preoperative MRI between our two cases could give useful presumptive information, which may indicate whether the worm is alive and that the patient is a surgical candidate. If highly enhanced and well localized compressive lesion like case 2 it indicates that the worm is alive and that the patient is a surgical candidate. In contrast, only inflammation without localization which suggests chronic inflammation like case 1 it is an indication that the worm is dead and that the patient is a poor surgical candidate.
As chemotherapy was employed in only 1 of the 10 patients described to date and was not shown to be effective, we did not prescribe any medical treatment to our patients1)