A giant intracranial hydatid cyst in a child: Intraoperative anaesthetic concerns.

INTRODUCTION

Intracranial hydatid disease has predominance (50-75%) in the paediatric age group and is caused by the larval stage of Echinococcus granulosus or Echinococcus multilocularis.[1] Anaesthetic management of a child with huge intracranial hydatid cyst of the brain is a case of concern for the anaesthesiologist.

CASE REPORT

A 4-year-old boy (weight 20 kg) presented with focal seizures in right arm since last 2 months and gradually increasing skull swelling on the left side since last 6 months. Computed tomography of the brain demonstrated a large, spherical, homogeneous cystic mass measuring 110 × 96 × 85 mm in the left frontoparietal region. The magnetic resonance imaging showed a well-defined lesion, hypo-intense on T1-weighted images and hyper-intense on T2-weighted images. There was a mural nodule (daughter cyst) in the posterior wall and midline shift of the brain (24 mm) towards the right side [Figure 1].

Figure 1

Magnetic resonance image showing mural nodule attached to the posterior wall of the cyst

Child was induced with sevoflurane-oxygen and trachea was intubated after inj.atracurium (10 mg). Fentanyl (40 μg) was given for intraoperative analgesia. Anaesthesia was maintained with propofol infusion (4-6 mg/kg/h) along with O2:N2O (50:50) and atracurium. An arterial line was secured, and child was monitored for continuous invasive blood pressure, heart rate, oxygen saturation, end-tidal CO2 (ETCO2), temperature, airway pressure and urine output throughout the intraoperative period. To decrease intracranial pressure (ICP) mannitol (1 g/kg) and hydrocortisone (5 mg/kg) were administered and keeping ETCO2 at 30-35 mm Hg. Apart from emergency drugs (epinephrine, atropine and sodium bicarbonate), injection pheniramine maleate, dexamethasone and salbutamol (inhaler) were kept to treat anaphylactic reaction if it presented intraoperatively.

A fronto-temporo-parietal craniotomy was done. Brain was well relaxed. The cyst was large and soft to touch. It was semi-transparent due to the presence of scolices and brood capsules [Figure 2]. Surgeon used hypertonic saline (3%) irrigation to separate the cyst from the surrounding brain parenchyma. Once cyst appeared free from the surrounding, head end of the operation table was lowered around 45° to extract the cyst with the help of gravitational force. During the extraction of the cyst from cranium to the collecting bowel, the cyst got ruptured. The cyst contents were aspirated immediately and hypertonic saline and hydrogen peroxide were administered into the remnants of cyst. Ruptured cyst was then resected completely.

Figure 2

Giant intracranial hydatid cyst during the intraoperative period

Child was monitored closely for anaphylaxis after rupture of the cyst. Child remained haemodynamically stable with no increase in airway pressure. He received hypertonic saline (200 ml) as irrigation fluid during surgery which was suctioned out continuously. Serum sodium was checked frequently to rule out hypernatremia. The blood loss during the surgery was approximately 200 ml which was replaced with packed red blood cells. Child was haemodynamically stable at the end of the surgery and was extubated. He was discharged on 10th postoperative day and was followed up regularly. After 1 year child was found to be normal and active with no h/o seizures.

DISCUSSION

Intracranial hydatid cysts are more frequently located in the supratentorial compartment, especially in the watershed area of the middle cerebral artery.[2] They can be classified as primary (single) or secondary (multiple).[3] The patients present with headache, nausea and vomiting (due to increased ICP), neurological deficits, hemiparesis, visual deficit, diplopia and seizures as per the location of the cyst.[4] Features of a significant rise in ICP did not develop in our case because of progressive increase in size of the calvarium in the child.

Hydrodissection of the cyst is recommended in which the cyst is separated from the brain gently by irrigating fluid between cyst wall and brain interface.[3] In our case, hypertonic saline (3%) was used for hydrodissection which decreases the tension inside the cyst by keeping the cyst in a hyperosmolar environment. It also acts as scolicidal agent.[5] The Dowling-Orlando technique remains the preferred method of extruding the intracranial hydatid cyst, in which the cyst is delivered by lowering the head of the operating table by 45° using gravity.[6] Other surgical options include puncture and aspiration of the cyst fluid and expulsion of the cyst by insufflations of air in the contralateral ventricle.[3]

Providing adequate surgical field for excision of large intracranial cyst in a child is a challenge for anaesthesiologist. Aims of anaesthesia include keeping brain well relaxed throughout the intraoperative period and prevent any movement of the patient during surgery; surgical field should be free of bleeding to assist the surgeon to excise the cyst smoothly.

Numerous scolicidal agents have been used to prevent recurrence of the cysts resulting from rupture of cyst and release of parasites’ protoscolices.[5] Hypertonic saline, although very effective scolicidal agent, may give rise to hypernatremia leading to seizure and dehydration of cerebral cells with shrinkage of the brain giving rise to subdural haematoma.[7] Therefore, frequent and regular monitoring of sodium is necessary. We used lesser concentration of hypertonic saline (3%) to prevent these complications and monitored serum sodium level regularly. Hydrogen peroxide is another scolicidal agent. It releases gaseous oxygen which has scolicidal property. Ouerghi et al. reported severe oxygen embolism after use of hydrogen peroxide in cases of thoracic hydatid cysts.[8] It has been found to produce haemodynamic instability even without embolism.[9]

Major complication of intraoperative rupture of hydatid cyst is life threatening anaphylaxis. Rupture of hydatid cyst releases highly antigenic contents into the circulation which causes IgE mediated Anaphylactic reactions with severe hypotension and increased airway pressure due to bronchospasm.[10] A high index of suspicion and early aggressive therapy with intravenous epinephrine along with administration of 100% oxygen are vital in the management of life-threatening anaphylaxis. Hydrocortisone is used for prophylaxis as well for treatment of refractory hypotension.[10] Other complications include development of subdural effusion, epidural haematoma and pneumocephalus.[11]

CONCLUSION

We successfully managed a case of giant intracranial hydatid cyst in a 4-year-old child in which cyst ruptured just at the time of extrusion. Relaxed brain, clean surgical field and smooth anaesthesia are essential for a good outcome. Various complications are expected during different stages of surgery, therefore, anaesthesiologist should remain alert and be prepared to prevent and treat any complications during surgery.