Echinococcosis of nervous system included cerebral echinococcosis and spinal echinococcosis. Cerebral echinococcosis could be divided into primary (CE) and secondary (AE) echinococcosis. AE was mainly due to the transfer of echinococcosis in other organs or tissues. Bone echinococcosis was rare in all echinococcosis, which accounted for 0.5% − 4% of all echinococcosis, the incidence of spine was the top11.
The symptoms of headache and neurological dysfunction in patients with CE appeared slowly and the frequency of epileptic attack was low. On the contrary, for AE, the symptoms of these above symptoms appeared early and even threatened patient’s life12. AE was almost originated from the liver, and its symptoms were very similar to those of intracranial metastasis. The most common neurological dysfunction was unilateral limb weakness, which was progressive aggravation. However, for patients with extradural or skull echinococcosis, hydatid cyst could destroy the dura and skull, which was manifested as a mass under the scalp13, 14. The symptoms were pain in the lesion site or radiation pain, showing gradual development. It could also show symptoms of spinal cord compression, such as nerve root and cauda equina injury. In this study, patients were accompanied with pains, epilepsy and neurological dysfunction. Therefore, all patients received operation in this study.
In imaging examination for cerebral echinococcosis, the results of CT scan indicated that the cystic disease was round, and the content of the cyst was low density shadow. But the CT manifestations of AE were similar to intracranial metastasis, with low density shadow. When the lesion was large, the surrounding edema was obvious and most patients had calcification. MRI could effectively indicate the CE of brain, which was characterized by round and clear boundary cystic lesions. MRI of AE were multiple mixed signal lesions with obvious perifocal edema and edema would be more clearly in enhanced scan. Therefore, cerebral echinococcosis needed to be differentiated from cystic neoplasm or intracranial metastasis. However, for patients with spinal echinococcosis, MRI indicated cystic or multicyclic masses, with signal intensity similar to that of cerebrospinal fluid. T1 weighted image indicated circular and multilocular low signal; T2 weighted image showed medium high signal, with continuous, smooth and sharp linear low signal around. Therefore, Echinococcosis of spine might be differentiated from bone tuberculosis and bone tumor15. In this study, one patient was misdiagnosed as vertebral metastases. Therefore, the possibility of echinococcosis should be considered for the patients with vertebral disease who came from pastoral areas.
Drug therapy (albendazole) was one of the main treatment methods of nervous system echinococcosis, but the effects remained controversial. The authors indicated that patients with multiple intracranial hydatid cysts, unable to achieve complete internal capsule resection, echinococcosis of other organs, and other cases of CE and AE might need to take albendazole. However, patients with cerebral echinococcosis who took albendazole might have poor efficacy due to the protective effect of blood-brain barrier on brain tissue16. In this study, all patients were treated with albendazole, and the short-term outcome was good, but long-term follow-up data were missing.
For cerebral echinococcosis, Dowling's technique9 was used by most neurosurgeon. But for lesions with functional or deep area, PAIR method10 was selected. The authors indicated that AE patients with single intracranial lesion, especially the superficial and non-functional lesion, might be removed as early as possible. However, for the patients with intracranial multiple lesions, doctors might consider according to the location, quantity, size and edema of lesions, combined with the symptoms and signs of the patients. When the high intracranial pressure increased continuously, part of the lesions of AE might be removed, or even a certain size of cranial bone might be removed to relieve the high intracranial pressure. For patients with spinal echinococcosis, the key to the operation was to remove the cyst wall of echinococcosis completely. However, there are important anatomical structures around the spine, such as spinal cord, nerve root, and the aorta in front of the vertebral body. In addition, the long-term pathological changes cause extensive adhesion between the diseased tissue and the surrounding and the weakness of the capsule wall itself. It is not easy to achieve complete extracapsular removal during the operation. At present, the most widely recognized and accepted method of spine reconstruction was bone transplantation17. Most commonly used method were titanium cage interbody graft18 or cage interbody fusion19 and polymethylmethacrylate20 to fill bone defects. All patients in this study received operation, but one patient recurred and refused treatment, finally died during the follow up time. However, some patients with echinococcosis relapsed more than ten years after neurosurgery. Therefore, regular follow-up of echinococcosis patients might be necessary.
However, there are some shortcomings might be discussed in this study. all patients in this study received operation, and lack of conservative treatment. This is a single center, retrospective study and follow-up time was short. Therefore, multicenter, large sample studies with long-term follow-up might be carried out in the future.