Chiari malformation type I (CMI) was first described in 1891 by Hans Chiari [1]. There has been a general consensus that surgical decompression is the treatment of choice in symptomatic CMI patients. [2-4]. Suboccipital craniectomy and C1 laminectomy is typically employed. However, other aspects of decompressive surgery is the subject of debate. Among the debated topics includes ideal amount of bone removal, need for duraplasty, type of material for duraplasty, subarachnoid dissection, and need for tonsillar shrinkage. This may or may not be accompanied by expansile duraplasty with autograft or allograft.

Currently, most neurosurgeons would perform posterior fossa decompression with duraplasty [5]. Posterior decompression along having the advantage of protection from postoperative complications related to dural and arachnoid space opening and reduced operative time. Decompression with traditional duraplasty carries additional risks such as meningitis, cerebral spinal fluid (CSF) leakage, pseudomeningocele, cerebellar ptosis, and hydrocephalus [6]. However, many surgeons believe it is essential to restore normal CSF dynamics, associated with a lower reoperation rate, and can attain symptomatic improvement [5,7,8].

Numerous materials have been advocated for duraplasty, including autologous, such as pericranium, fascia lata, posterior atlantooccipital membrane, ligamentum nuchae, splenius capitis muscle flap, and non-autologous such as bovine pericardium, cadaveric dura, synthetic bovine collagen matrix (Duragen), acellular human dermis allograft (AlloDerm), expanded polytetrafluoroethylene (PTFE), and porcine small intestinal submucosa (Durasis) [9-13].

Despite several decades of experimentation and investigation of a wide range of materials, no consensus has been reached on the ideal dural substitute. An ideal graft would provide watertight closure without promoting excess arachnoid scar formation and minimize inflammatory response. In general, many surgeons prefers autologous materials over nonautologous substitutes for their lack of immunogenic complications. However, traditional autologous duraplasty still had a high incidence of complications from CSF leak [14]. This maybe due to the dissolution of dura substitute devoid of its blood supply during graft harvest.Therefore, an autogenous dura substitute with blood supply in combination with a water-tight suture technique could be an ideal choice for the treatment of CMI. We present our institutional experience with a modified autogenous duraplasty using pedicled autologous deep fascia.

Materials and Methods

Patients Population

Approval for the study was obtained from the Ethical Review Board of our hospital, and all patients provided written informed consent to participate in the study. This retrospective study was performed at the First Affiliated Hospital of Harbin Medical University. The radiological criterion for diagnosis of the Chiari I malformation requires a downward herniation of the cerebellar tonsils greater than 5mm below the foramen magnum. The primary inclusion criteria were

1. Radiological evidence of CMI;
2. Tussive suboccipital headache, cranial nerve dysfunction, and/or cerebellar symptoms;
3. Age between18 to 70 years; and
4. Failed conservative therapy [15]. Patients were excluded if they had history of cervical spinal surgery. Surgery was recommended for symptomatic patients only. This is a single-surgeon series.

Surgical Technique

A standard posterior fossa decompression (PFD) through a midline suboccipital craniectomy and C1 laminectomy was used in each patient. The patients were placed in concorde position. Suboccipital incision was planned in the midline from roughly the inion to the C3-C4 level. Care was taken to remain within the midline avascular raphe, and expose subocciput and posterior arch of C1. During the process, trapezius, semispinalis capitis, musculi rectus capitis posterior and rectus capitis posterior minor were separated from the midline, and detached from occipital bone and C1 posterior arch. Dura was exposed after suboccipital craniectomy and removal of C1 lamina. A Y-shaped dural incision was made, keeping the arachnoid intact

The deep fascia of right or left semispinalis capitis, musculi rectus capitis posterior and rectus capitis muscle was sharply separated with scissors, making sure to keep the facia intact. A 4cmx3cm trapezoid facia was dissected, with the facia of the rectus capitis posterior minor as the pedicle in the size about 1.5cm. This pedicle was dissected as deep as we can till it reached the midline. Then the separated deep facia was reversed with the facia of the rectus capitis posterior minor as the pedicle. A vascular suture technique was applied to get a water tight seal with 6-0 Prolene as shown in (Figure1). Subsequently, gel foam was used to cover the operative field. The incision was closed in anatomical layers.

Clinical Outcome

Surgeon and anesthesia operative records were reviewed to document intraoperative findings, blood loss, and operative time. Computed tomography scans (CT) were evaluated for the presence of subarachnoid hemorrhage, epidural hematoma or fluid collections after the decompression operation. Lumbar puncture, blood test and CSF bacterial culture were taken for the patients with persistent postoperative fever and suspected meningitis. Follow-up MRI scans were reviewed for the evidence of hydrocephalus, pseudomeningocele or delayed extra axial fluid collections, and the changes of tonsil herniation and syringomyelia.