Anesthetic challenges during perioperative management of patient undergoing repair of basal encephalocele with cleft palate.

Sir,

Basal encephalocele is a rare craniofacial anomaly with an estimated frequency of 1 per 100,000 live births.[1] Trans-sphenoidal encephalocele is the rarest form, comprising only 5% of basal encephaloceles.[2] A literature search revealed few case reports emphasising the neurosurgical management of such cases. The case of basal encephalocele with cleft palate is the rarest of all forms of encephalocele. The anesthetic concerns include difficult airway, mask ventilation, encephalocele rupture during intubation, need for invasive monitoring, sharing of airway with surgeon, lumbar drainage in pediatric patient, plan of extubation and postoperative management of complications, mainly hypothalamic pituitary axis dysfunction. To the best of our knowledge, no case report has highlighted anesthetic concerns in these patients.

A 16-month-old male child weighing 8 kg presented to the Department of Neurosurgery with complaints of intraoral swelling [Figure 1], with increase in size on crying and difficulty in breast feeding with nasal regurgitation of fluid and milk since birth. There was history of recurrent respiratory tract infection. Magnetic resonance imaging revealed defect in the base of the skull in the posterior part of anterior cranial fossa and ethmoid region, with meningocele sac protruding through the defect in the palate and projecting into the oral cavity along with corpus callosum agenesis [Figure 2]. The patient was diagnosed as a case of basal encephalocele with cleft palate. Preoperative routine laboratory investigations and hormone profile were normal. The patient was scheduled for reduction of trans-sellar trans-sphenoidal encephalocele with repair of anterior skull base defect through a trans-palatal approach. On the day of surgery, the patient was nebulised with normal saline and premedicated with oral atropine (10 mcg/kg) 1 h prior to surgery. In the operating room, the routine monitors were attached and intravenous (IV) access established with a 24 G cannula under anesthesia with sevoflurane in 100% oxygen. IV fentanyl 2 mcg/kg and rocuronium bromide 1 mg/kg were administered to facilitate tracheal intubation. Careful direct laryngoscopy (DL) was performed using a Miller's blade (size no. 1) to avoid injury to the oral cavity swelling. On DL, the Cormack Lehane grade was II and the swelling obstructed the view of laryngeal inlet. Wet cotton gauze was placed over the swelling to prevent injury during intubation and the trachea was intubated using an 18 F uncuffed flexometallic tracheal tube (ETT) with stylet. The ETT was secured on the left corner of the mouth and oropharyngeal packing with saline-soaked gauge was performed. General anesthesia was maintained with sevoflurane (concentration 1–1.5%) in oxygen/nitrous mixture (50:50) and intermittent boluses of fentanyl and rocuronium. End-tidal carbon dioxide was maintained in the range of 32–35 mmHg. Axillary temperature was monitored and normothermia was maintained. Right internal jugular vein was cannulated using a 5 F double-lumen catheter under ultrasonic guidance. Right posterior tibial artery was cannulated with a 24 G arterial cannula for invasive blood pressure monitoring. Depth of anesthesia was monitored using bi-spectral index, and maintained between 40 and 60. Intraoperatively, prewarmed normal saline was used as maintenance fluid. Total duration of surgery was 8 h. At the end of surgery, lumbar drain was placed in the subarachnoid space at the L4–L5 spinal level using an 18 G epidural catheter. Elective mechanical ventilation was planned in the postoperative period in view of anticipated airway edema due to the long duration of surgery involving the oropharynx and the prolonged retractor application. The ETT was replaced with a portex 4.5 mm ID uncuffed ETT after throat pack removal. On the next morning, the trachea was extubated after proper airway assessment and full recovery of consciousness. On postoperative Day 8, the patient developed hyponatremia (Na+ = 112 meq/L) and had multiple episodes of focal seizures. Hyponatremia was corrected using 3% hypertonic saline through a central venous catheter. Loading dose of phenytoin (15 mg/kg) was given intravenously and continued 30 mg BD orally. The patient was discharged from the hospital on postoperative Day 13 with full Glasgow Coma Scale (GCS) score and normal laboratory reports.

Figure 1

A 16-month-old child with trans-sellar trans-sphenoidal encephalocele protuding into the oral cavity (bold arrow)

Figure 2

Magnetic resonance imaging of the head: (a) saggital section and (b) coronal section, showing trans-sellar trans-sphenoidal encephalocele with herniation through the hard palate (bold white arrow)

Patients in the pediatric age group require special attention due to their anatomical, physiological and pharmacological differences from adults. Associated anomalies like trans-sellar trans-sphenoidal encephalocele and cleft palate impose greater challenges to the anesthesiologists. Upper airway obstruction, microcephaly, corpus callosum agenesis, hypothalamic pituitary dysfunctions and mid-facial anomalies may coexist with basal encephalocele.[1-3] As a consequence of airway obstruction, respiratory distress, episodes of apnea, difficulty with feeding and failure to thrive may be seen.[4]

These patients have increased chance of respiratory tract infection due to regurgitation of feed through cleft palate; therefore, optimisation by nebulisation with normal saline is helpful and premedication with atropine is useful due to its vagolytic and antisialagogue action. Airway management is a major concern in these cases due to protrusion of encephalocele into the oral cavity through the cleft palate. This may cause difficulty in laryngoscopy as well as obstruct the view of laryngeal inlet and passage of ETT. Also, there is the likelihood of causing injury to the swelling during intubation. Wet gauge over the swelling can be used to prevent injury and use of straight blade may provide a better view of the larynx in such cases. Oropharyngeal packing prevents trickling of blood and secretions into the trachea and esophagus and also prevents dislodgement of the ETT. Invasive monitoring (central venous pressure and arterial pressure) in such patients plays a crucial role due to difficult peripheral venous access, intraoperative fluid management, repeated sampling, postoperative administration of antibiotics, electrolyte disturbances and possibility of postoperative hypothalamic dysfunction, as observed in our patient. To reduce the chances of cerebrospinal fluid (CSF) leak, it is advisable to place a lumbar drain intraoperatively under anesthesia in these pediatric patients. Extubation of such patients should be planned carefully considering the long duration of the surgical procedure, handling of the oropharynx and retractor application, all of which may contribute to the edema of the airway. Proper airway assessment and full GCS score should be ensured before extubation. Major concerns in the postoperative period are management of fluid and electrolyte disturbances, diagnosis and treatment of new neurological deficits, seizure, pituitary hypothalamic dysfunctions, CSF leak and meningitis. The transpalatal approach may further increase the risk of postoperative meningitis due to contamination by oral and nasal bacterial flora. Manipulation in the areas of the hypothalamus and pituitary gland can cause endocrinological complications such as anterior pituitary insufficiency, diabetes insipidus, syndrome of inappropriate antidiuretic hormone secretion and cerebral salt wasting syndrome.

Although cases of basal encephalocele are rare, they are a challenge to the anaesthesiologist. Proper assessment, anticipation of the problems, use of multimodal monitoring, vigilance, careful extubation, early diagnosis and treatment of intra- and postoperative complications can lead to successful management and good outcome.