Suboccipital Craniotomy and C -1 Laminectomy for Arnold Chiari Malformation - Research Paper Example

Running Head: DECOMPRESSION SURGERY: SUB – OCCIPITAL CRANIOTOMY AND C LAMINECTOMY FOR ARNOLD CHIARI MALFORMATION Decompression Surgery School Author Note This research is being submitted on December 26, 2011 to NAME OF PROFESSOR in partial fulfillment of the requirements for ------------ course. Introduction Chiari malformation is an uncommon condition where there is an abnormal protrusion of the tissue of the brain to the spinal canal as a result of skull deformities that press towards the brain (Pakzaban, 2010 and Mayo Clinic, 2010). There are several types of Chiari malformation. The type I, which is an adult form, develops on the late childhood and adulthood, when the skull and brain are grown. Type II Chiari malformation is present at birth and is the most common pediatric form of Chiari malformation. The students of Arnold Chiari named type II malformation as Arnold Chiari Malformation in honor to his contribution on the definition of this abnormality (Pakzaban, 2010 and Mayo Clinic, 2010). Pollock (2008) noted that Arnold-Chiari Malformation consists of variety of symptoms making its diagnosis difficult to establish. This is characterized by the presence of skull depression, reduction in the pathways of cerebrospinal fluid, and protrusion of cerebellar tonsil into the spinal canal through the foramen magnum that cause various problems in the sensory – motor (Pollock, 2008). The following are noted as indications to operate patients with Chiari Malformations. These include failure to thrive, progressive spasticity or weakness of the upper extremities, pressure inside the head/neck, breathing problems, uncoordinated movement, speech problems, deterioration of alertness, and problems in walking (Venes, et al., 1986 and Columbia University Medical Center, 2011). Venes, et al (1986) noted in their study that out of 14 patients with meningomyelocoele with corresponding Arnold – Chiari Malformation in the study, nine of them had improved significantly after the surgery and three patients experiencing progressive deterioration were stabilized by surgical intervention. Vene, et al. (1986) added that in the treatment of the Arnold – Chiari II Deformity, fourth ventricular decompression by fenestration and internal shunting is reportedly tolerated well even among the young infants. The goal of treatment for Arnold – Chiari Malformation is to restore a normal CSF flow in the foramen magnum region through surgical procedure that includes cervicomedullary junction decompression (Pakzaban, 2010). Pakzaban (2010) noted that surgical procedure include suboccipial craniectomy, cervical laminectomy, duraplasty, and arachnoid dissection. Pre-operative According to Pakzaban (2010), the surgical preparation for Arnold – Chiari decompression procedure is similar with the elective surgical procedure. The general health of the patient is checked prior to the procedure. Routine laboratory check up is done to all patients, which include, the CBC, basal metabolic panel, PT, aPTT, chest radiograph, and ECG. Blood typing and screening are also obtained. After midnight, the patient is restricted to nothing per orem (NPO) and is admitted for surgery in the morning (Pakzaban, 2010). Compression devices such as thigh high anti – embolic stockings are applied, and an hour prior to incision, prophylaxis antibiotic such as cefazolin and vancomycin is given together with dexamethasone. A Foley catheter will be inserted (Pakzaban, 2010). Intra – Operative Procedure The surgical procedure that will be performed among patients with Arnold – Chiari Malformation is known as Decompression Surgery: Sub Occipital Craniotomy and C-1 Laminectomy. In the operating table, the patient is placed in a prone position with a 20 – 30 degree elevation of the head of the bed with the arms of the patient placed at his side, and all pressure points are padded. In between parallel rolls of gel, the abdomen and male genitalia are allowed to hang freely (Pakzaban, 2010). At the craniocervical junction, the neck is flexed and on the other hand, at the cervicothoracic junction, it is extended. In a 3 – point skeletal fixation, the head is fixed in a neutral position using a Mayfield head holder. Along the midline of the occiput, a strip of hair is shaved which extends above the inion. The occipital area is then prepped and draped (Pakzaban, 2010). A 2 – 3 cm midline incision is created from the inion to the upper cervical spine, and from the upper pole of incision, a large pericranial graft is to be harvested. Depending on the extend as to where the tonsillar descent is exposed, the inion through the upper C2 laminar aspect area is exposed; however, the neurosurgeon must leave intact the attachment of the muscles to the superior nuchal line through the occipital bone just superior and lateral to the foramen magnum is stripped off. A judicious use of bipolar coagulation and Gelfoam is used to control the bleeding between large epidural veins whenever damaged (Pakzaban, 2010). From the inferior nuchal line to the foramen magnums’ posterior and lateral rims will carry out a conservative suboccipital craniectomy. In between the two cerebellar dural hemispheres, a prominent internal occipital crest will extend, and must be resected. A neurosurgeon should note that cerebellar ptosis may occasionally result when the occipital bone is resected zealously. A neurosurgeon should also note that the goal for this operative procedure is not to decompress the entire foramen fossa but the foramen magnum alone. If the tonsils descend to C1 to C3 levels, a wide C1 to C3 laminectomy must be carried out depending to what level the tonsil descends until the curvature of dura is appreciated. The opening of dura is done in a Y – shaped fashion having its oblique limbs of the Y to transect the occipital sinus paired inferior limbs. While the Y limb is being transacted, the edges of dural are oversewn or coagulated. The inferior extension of the falx cerebri will be divided when the oblique Y limbs comes together where its vertical limb extends down the mid spinal dura. A tight dural band constricting the dura is observed oftentimes at the level of foramen magnum among patients with Chiari Malformations and is incised along the midline. The sutures are tented to the suboccipital muscles and fascia along the dural leaflets (Pakzaban, 2010). Under the operating microscope, the cistern magna of the arachnoid is dissected to ensure unobstructed flow of the CSF through the fourth ventricle outlet around the junction of the cervicomedullary area. This is observed predominantly among patient having syringomyelia (Pakzaban, 2010). To mobilize the tonsils superior – laterally and to expose the obex and fourth ventricular floor, the adhesions of the arachnoid located between the two cerebellar tonsils and amid every tonsil and medullar are divided carefully. To avoid tonsillar segment injury of the posterior inferior cerebellar arteries, extreme care must be taken (Pakzaban, 2010). In cases of patients with syringomyelia, a limited subpial resection of the tonsils must be carried out if the tonsils are adherent to the medulla densely. On the other hand, limited midline myelotomy to decompress directly the syrinx must be carried out among patients with high cervical syringomyelia or syringobulbia cervicomedullary nerve tissue is thinned down to thin membrane (Pakzaban, 2010). Watertight duraplasty must be carried out carefully using the pericranial graft that was harvested at the start of the operative procedure, and before the last suture will be tied, a warm saline will be placed to fill the intradural compartment. Hence, any leakage noted must be repaired meticulously. A fibrin glue or DuraSeal glue are used to cover duraplasty, and a muscle hemostasis must be secured meticulously after the removal of the retractors to avoid epidural hematoma postoperatively. Lastly, closure of wound is done in layers (Pakzaban, 2010). According to Pakzaban (2010), the decompression procedure done in Arnold-Chiari Malformation or Chiari II malformation is similar in fashion with the exception of multilevel cervical laminectomy procedure. Also, there is no attempt to dissect the cerebellar tonsils that adheres tightly from the brainstem in Chiari II made during the procedure. Post-operative During the first 24 hours post – surgery, the patient is observed carefully for any signs for dysfunction of the brainstem, in particular, apnea. According to Pakzaban (2010), all Chiari patients are placed in the ICU during the first postoperative night, and as long as no complications on the second postoperative day, the patient is mobilized rapidly, and discharged when ambulatory and able to eat without vomiting with an intact neurological function. Patients are prescribed with analgesics and muscle relaxants to control incision pain and muscular spasms. Soft cervical collar is also prescribed to provide partial pain relief (Pakzaban, 2010). References Columbia University Medical Center. (2011). Chiari Malformation. Retrieved 24 December 2011, from http://www.columbianeurosurgery.org/conditions/chiari-malformation/ Mayo Staff. (2010). Chiari Malformation. Retrieved 22 December 2011, from http://www.mayoclinic.com/health/chiari-malformation/DS00839 Pakzaban, P. (2010). Chiari Malformation. Retrieved 21 December 2011, from http://emedicine.medscape.com/article/1483583-overview#a0101 Pollock, N. (2008). The Complexity of Arnold – Chiari Malformation. Retrieved 22 December 2011, from http://serendip.brynmawr.edu/exchange/node/1818 Venes, J., Black, K., and Latack, J. (1986). Pre – operative evaluation and surgical management of the Arnold – Chiari II Malformation. Journals of Neurosurgery, 64(3): 363- 70. Read More