Giant Occipital Encephalocele: A Case Report, Surgical & Anesthetic Challenge

Background: An encephalocele is a congenital neural tube defect characterized by herniation of cranial contents through a defect in the cranium and is caused by failure of the closure of the cranial part of the developing neural tube. An encephalocele is termed as “giant encephalocele” when the size of encephalocele is larger than the size of the head. They depend on size of the sac, percentage of neural tissue content, hydrocephalus, infection, and other associated pathologies for a favorable neurological outcome. Case Presentation: We report a case of a four month old boy with a Giant Occipital Encephalocele about 21 x 15 x 19 cm in size, who was a surgical and anesthetic challenge for us. Intubation was achieved in lateral position. Part of occipital and cerebellar parenchyma was present in the sac and bony defect was approximately 2.5 cm in occipital bone in midline. We did Surgical Excision and Repair with a good overall outcome. Conclusion: Perioperative management of a Giant Occipital Encephalocele is a challenge for both anesthesiologist and neurosurgeon. Managing such a case demands search for other congenital abnormalities, expertise in handling airway and proper intraoperative care. Careful planning and perioperative management are essential for a successful outcome.

Cesarean section at term, in some local hospital and was taken to a local pediatrician for evaluation. He was not advised for neurosurgical opinion and the child was taken back to home. He grew up till the age of 4 months, when it became di cult for the mother to nurse the child and he fell from her lap and was taken to another nearby hospital who referred the child to our neurosurgery department. On examination, the child appeared active. He had a huge occipital swelling measuring about 21 x 15 x 19 cm in size. (Fig. 1,A & B) The overlying skin was intact, though few areas of skin necrosis due to pressure were seen. No obvious traumatic injury noted. Swelling was cystic and transilluminant. Anterior fontanelle was lax and open, measuring about 3.5 x 2.5 cm. Child was moving all four limbs, power and tone were normal. With the aforementioned clinical ndings, a diagnosis of Giant Occipital Encephalocele was made.
Routine investigations were normal. His Magnetic Resonance Imaging (MRI) Brain Plain was done which reported a Cerebrospinal Fluid (CSF) containing sac with brain parenchymal tissue herniating through a defect in posterior occipital bones in midline. It measured approximately 21 x 15 x 19 cm. Bilateral lateral and third ventricle were normal. So, they concluded it to be a huge meningoencephalocele without hydrocephalus. (Fig. 2

, A & B)
Parents were counselled in detail about it and after taking informed written consent, we proceeded for surgical excision and repair. It was a great challenge for our anesthetist to intubate this child. Intubation was achieved in lateral position. After intubation, the child was kept in lateral position. Cleaned and draped while holding the encephalocele in our hands. Incision was given along the neck of sac and deepened through skin layers. Dissection done layer by layer and excised the sac along with dysplastic brain tissue. Part of occipital and cerebellar parenchyma was found in the sac. Dural venous sinuses were not involved. Dural layer was identi ed, brain tissue reduced through a bony defect of 2.5 cm size in occipital bone in midline and closure done with coated Vicryl (polyglactin 910) 4 − 0 suture. Valsalva maneuver performed. No CSF leak noted. Subcuticular layer closed with Vicryl (polyglactin 910) 3 − 0 suture. Skin closure done with Prolene (polypropylene) 3 − 0 suture. Child had smooth extubation and started to feed after 3 hours of surgery. There was minimal blood loss during the surgery, so blood transfusion was not done. The baby didn't develop hydrocephalus and was discharged after 3 days.

Discussion:
The meningeal membrane covering the giant encephalocele is either covered by a normal, dysplastic or a thin membrane. Clinically, the presentation of giant occipital encephaloceles is evident due to their characteristic swelling. [2] The contents of occipital encephalocele mainly include meninges and occipital lobes. It may also comprise of ventricles, cerebellum, and brain stem. The factors in uencing the outcome in the occipital encephalocele patients are site, size and herniation of the brain into the sac. Site, size, and the amount of brain herniated inside the sac determines the prognosis. The presence of brainstem or occipital lobe with or without the dural sinuses in the sac along with hydrocephalus also in uence the outcome of the case. [4] The large-sized swellings may possibly have a remarkable brain herniation, an abnormality of the underlying brain and microcephaly. The clinical examination comprises the examination of its size, extent, amount of protrusion and its location along with the size of bony defect. [2] The size of the head holds a signi cance importance for clinical suspicion of microcephaly or hydrocephalus and extracranial anomalies. [2] MRI brain is the usual investigation of choice along with the three dimensional Computed Tomography (CT) that further helps in evaluating the deformity and hence the surgical procedure can take place as soon as possible to avoid further neurological de cits. [5] Giant encephaloceles are rare; surgical procedures are a challenging task for the anesthesiologists, as well as the neurosurgeons. The challenges present are mainly due to its complicated site, enormous size, associated bulging contents resulting in intracranial anomalies, intraoperative blood loss, and prolonged anesthesia. [6] The major aim of the anesthesiologist is to avoid the premature rupture of the encephalocele intraoperatively. The occipital site of the encephalocele causes a hindrance with the intubation as due to a di cult airway caused by the restriction of the neck movement. This further leads to an inability of having an optimal tracheal intubation position. [3] The operative procedure also includes the management of possible loss of large quantities of CSF causing superimposed electrolyte imbalance. Infants with encephalocele can develop sudden hypothermia due to dysfunction of autonomic control below the present defect. [3] Thus immediate consideration and management has to be given to hypothermia, blood loss, and its associated complications. The surgery is advised to be done as soon as possible to avoid life threatening complications such as Central Nervous System (CNS) infections, respiratory distress, aspiration pneumonia, irreversible impairment of vagus nerve and hypothermia. [5] The table below, comprises all the reported cases to the author's knowledge. (Table 1) [3,4,[9][10][11][12][13][14][15][16][17][18][19][20][21] The main aim is to portray the different and most commonly used surgical procedures in the management of giant occipital encephaloceles. The most frequently used method is simple resection and dural repair.
Expansion Cranioplasty is one of the surgical procedures that consists of a mesh to provide room for the protruded sac. Another technique used is done through ventricular volume reduction. It is a two-step technique; for start it increases the ventricular pressure inducing hydrocephalus followed by a ventriculoperitoneal shunt. The ventricles then contract and the protruded tissue repositions itself inside the cranium. For the herniated cerebellar and occipital parenchyma, an incision is made in the tentorium to create an infratentorial area for the herniated tissue to retract. [7]  prone position excision and repair of sac was done.
16 [3] 2014 1 month Occipital No associated ndings The dysplastic portion of the occipital lobe was removed, and tight dural closure was achieved in two layers.
17 [11] 2014 6 day Occipital Delayed cry at birth, hypotonic with decreased spontaneous movements and had respiratory distress.
Dysplastic cerebellar tissue with a herniated sac was excised, and the primary closure of the defect was performed.
19 [15] 2016 40 days Occipital Persistent elevation of serum potassium levels The child underwent complete surgical excision and repair of the meningoencephalocele.
20 [20]  The sac with dysplastic brain tissue was excised and closed in a single layer using continuous suture.
26 [16] 2017 1 month Occipital No associated ndings The sac was dissected out and the dysplastic brain tissue was excised. The sac was closed in a single layer using continuous suture, skin and subcutaneous tissue was closed.
Modern day neurosurgical techniques along with neuroimaging and neonatal intensive care with neurological facilities have greatly improved morbidity and mortality rate in the management of encephaloceles. [8] Postoperatively, complications such as hypothermia, raised intracranial pressure (ICP), apnea, cardiac arrest, CSF leak, and infection can arise and hence need to be managed effectively. However, in our case no complications were present. Alongside all present di culties, intubation and anaesthetic management in our patient were successfully achieved.

Conclusion:
Perioperative management of a Giant Occipital Encephalocele is an extensive team challenge for both anesthesiologist and neurosurgeon. These patients have a di culty in attaining the supine position. Endotracheal intubation is achieved in the lateral position. Prognosis is mainly dependent on the extent of the invasion of cranial contents into the sac. Due to the herniation of parts of the brain, there is a signi cant rise in the di culty level of the surgical procedure. There is always a higher risk of infection involved in giant encephaloceles usually due to CSF leakage. In order to avoid superimposed complications, carrying out the operative procedure at an early age is highly bene cial.

Consent for Publication:
Written informed consent was taken from the mother of the child for publication of case report and accompanying images.
Availability of data and materials: All data is within the article.
Competing interests: None of the authors has any con ict of interest to disclose. We con rm that we have read the Journal's position on issues involved in ethical publication and a rm that this case report is consistent with those guidelines.

Funding:
No funding was required for this work.
Authors' contributions: SZ and AK wrote the manuscript. AK is involved in the surgical management of the patient. Both authors read and approved the nal manuscript.