Another alternative in the treatment of hepatic cystic echinococcosis (Part two)

Our country is located in one of the main foci of hydatid endemism (Balkan Peninsula). For this reason, greater attention should be exercised in the recognition and treatment of this pathology, which causes serious social and economic consequences.

Echinococcosis (Hydatidosis) is a parasitic zoonosis caused by the mature and larval stage of the cestode Echinococcus granulosus. Reports on this pathology belong to the 4th century BC, described by Hippocrates as cysts filled with water, and since then, certainly, there have been many advances regarding the methods of analysis, control, and possibilities of preventing this disease, surgical treatment techniques as well as less invasive methods. (2)

The parasite, to develop, needs the presence of two mammals, as hosts, to complete its life cycle; a definitive host where the mature tapeworm develops in the small intestine as well as an intermediate host in which the metacestodes develop in organs. The definitive host is usually a carnivore that gets infected by ingesting protoscoleces. These can be thousands inside each cyst and each is capable of developing into a sexually mature form (4 – 7 mm in length). The mature forms produce eggs 20-40 micron and each contains a single embryo (oncosphere), which is eliminated with the feces of the definitive host. The eggs are capable of surviving for a long time in various environments where they fall and are ingested by a large number of herbivorous species that thus are considered as intermediate hosts. 3) In Albania, only the form of Echinococcus Granulosus (Cysticus) that is transmitted from dogs to domestic animals has been observed. Humans are infected through direct or indirect contact with the infected dog.

Echinococcus granulosus is a small tapeworm, 2 – 7 mm in length, consisting of:

• Head with 4 suckers
• Neck that is short and narrow
• Body (strobila) that usually consists of 3 or 4 proglottids that sometimes can reach up to 6.(4)

Fig. 7. Mature proglottid of Echinococcus granulosus filled with eggs. (4).

From the mid-80s, a less invasive technique was introduced in Europe for the treatment of hepatic hydatid cysts. This technique is less dangerous and more economical than surgical treatment.

The technique in question is named PAIR (Puncture, Aspiration, Injection, and Reaspiration). The main purpose of this paper is the description and general awareness of these methods, and why not, their possible application in our country, certainly in suitable cases.

PAIR is the most appropriate technique for hepatic cysts CL, CE1, CE2, and CE3, especially those with a diameter larger than 5 cm as well as for multilocular and multiple cysts, always larger than 5 cm. (5).

This technique consists of percutaneous puncture under Ultrasound, aspiration of the cystic content, and injection of a substance with scolicidal action (usually 95% sterile alcohol) in a quantity equal to 1/3 of the aspirated fluid and finally re-aspiration of the cystic content after 5 minutes. When 15% NaCl can be used, it should be re-aspirated after 15 to 20 minutes. (5)

In its early days, the PAIR technique was reserved for patients who could not undergo or who refused surgical intervention. After the initial positive experiences, all cysts of the groups CE1 and CE2 that did not respond positively to medical therapy were treated with the PAIR method. (6)

It is emphasized that this technique should only be applied by expert doctors, under the care of an intensive therapy specialist who must be ready to intervene in case of intraoperative complications.

The PAIR technique should only be applied to patients who have previously undergone chemotherapeutic treatment with Benzimidazoles at least for 4 days before the treatment and at least for 1 month post-PAIR with Albendazole or for 3 months with Mebendazole, to reduce the risk of secondary cyst recurrences.

PAIR is the most suitable technique for the treatment of hepatic cysts CL, CE1, CE2, and CE3, especially when they have a diameter larger than 5 cm as well as for multilocular and multiple cysts, always when they are larger than 5 cm in diameter. (7)

Fig . 8 : Schematic presentation of the PAIR procedure. WHO/CDS/CSR/APH/2001.6 . PAIR: Puncture, Aspiration, Injection, Re-Aspiration An option for the treatment of Cystic Echinococcosis World Health Organization Department of Communicable Disease, - Surveillance and Response. Page 20.

Legend of Fig. No. 8 :

1. Puncture and microscopic evaluation of the cystic content.
2. Aspiration of the content.
3. Injection of the scolicidal substance
4. Reaspiration of the injected substance
5. The cyst must be punctured transhepatically and not on the most exteriorized part.

This technique can also be used in patients who have presented a recurrence after a surgical intervention or who have not had an effect from chemotherapy.

Meanwhile, it is contraindicated in the treatment of superficial cysts, those that are calcified or those that have communications with the biliary ducts (due to cholangitis that can be caused by the contact of scolicidal substances with the biliary lines. (8)

Recurrence cases are described as rare (1 – 6 %), while lethal outcomes . (0,1%). (9)

In the world literature, there are many references to the pharmacological treatment of hydatid cysts, with results that are noteworthy.

The authors (9) have followed and documented over 2000 cases of patients treated with benzimidazole preparations and 12 months after the treatment have presented these achieved results :

• 10 – 30% of patients have had a regression of the cysts.
• 50 – 70% have had cyst degeneration or even a reduction in volume.
• 20 – 30% have not presented any change.