✓ A new technique for performing a posterior rib and multistranded cable atlantoaxial fusion in children is described. The technique has been used successfully, in two patients 22 and 18 months of age, respectively. In both cases, fusion was used to augment C1–2 transarticular screw fixation, and solid arthrodesis was achieved without a halo orthosis.
Douglas L. Brockmeyer
Douglas L. Brockmeyer, Meghan M. Brockmeyer and Taryn Bragg
Congenital craniovertebral anomalies are relatively common, but anomalies leading to overt craniocervical instability may be difficult to recognize and treat. The authors present a series of patients with atlantal hemi-rings, a disorder resulting in congenital craniovertebral instability. Presentation, treatment, imaging, and follow-up data obtained in patients with atlantal hemi-rings were assessed to identify factors relevant to craniocervical instability.
Nineteen patients were identified with atlantal hemi-rings, defined as a bony discontinuity of the C-1 ring in conjunction with lateral displacement of the C-1 lateral masses (as seen on coronal CT scans). Clinical and radiological characteristics were analyzed, including patient age at presentation, extent of occipitocervical motion, amount of C-1 lateral mass displacement, associated craniocervical anomalies, integrity of the transverse ligament, and neurological status.
The mean patient age at presentation was 22 months (range birth to 9 years). The mean amount of occipitocervical translation seen on dynamic imaging was 9 mm (range 2–20 mm). Four patients required occipitocervical fusion at presentation. The remaining 15 patients were monitored for a mean of 20 months, and 9 ultimately underwent fusion. Surgery was also recommended for 4 of the remaining 6 children.
This report describes the radiological and clinical characteristics of patients with atlantal hemirings and craniocervical instability. The authors believe that this anomaly is the underlying cause of progressive instability in a significant proportion of patients with craniocervical abnormalities. The presence of atlantal hemi-rings should prompt immediate and thorough neurosurgical evaluation.
Douglas L. Brockmeyer and Ronald I. Apfelbaum
✓ Posterior occipitocervical stabilization procedures were successfully performed in 10 patients (nine boys and one girl) 16 years of age or younger by using C1–2 transarticular screws coupled with a rigid occipitocervical construct. The average length of follow-up evaluation was 18.8 months (range 5–37 months). No implant failed and all fusions were successful without the use of an external orthotic halo device.
Sarah T. Garber and Douglas L. Brockmeyer
Subaxial cervical instability in very young or small-for-age children is uncommon and typically arises from trauma or skeletal dysplasia. Various operative techniques have been used to achieve stabilization in pediatric patients with evidence of instability, including anterior, posterior, and combined approaches. In this study, the authors report their results with subaxial cervical instability in this patient population treated using a static single-screw anterior cervical plate (ACP) system and allograft fusion.
In a retrospective chart review, the authors identified all patients 6 years of age or younger who underwent an anterior cervical fusion procedure using a static single-screw ACP system either as a stand-alone construct or as part of an anterior-posterior stabilization procedure. Reasons for fusion included trauma, tumor, and congenital anomalies.
Five patients 6 years of age or younger underwent anterior cervical fusion using a static single-screw system during the 19-year study period. Follow-up ranged from 12 to 51 months (mean 26.8 months). Two patients underwent repeat surgery, one 7 days after and the other 21 months after their initial procedure. At last follow-up, a mean vertical growth of 22.8% was seen across the fused segments, with no evidence of kyphotic or lordotic abnormalities.
In very young or small-for-age children, the use of a static single-screw ACP system appears to be a safe and effective option to manage subaxial cervical instability. Bony fusion and continued longitudinal growth occur within the fused segments, with no evidence of long-term cervical malalignment.
Daniel Couture, Nathan Avery and Douglas L. Brockmeyer
Rigid occipitocervical instrumentation for craniovertebral instability is gaining widespread acceptance for use in pediatric patients; however, most of the instrumentation has been modified from adult-sized hardware. The Wasatch loop system (formerly the Avery-Brockmeyer-Thiokol loop system) is a rigid occipitocervical fixation device designed specifically for use in children. It affixes to the occiput and incorporates either C1–2 transarticular screws or C-2 pars screws. It is preformed and is available in a variety of sizes. The authors describe their clinical experience and long-term follow-up experience with the first 22 patients.
An institutional review board–approved retrospective review of medical records and radiographs was performed for patients who underwent occipitocervical fusion with the Wasatch loop. The mean patient age was 4.9 years (1.2–13 years), and the overall mean follow-up was 4 years (1.5–6.5 years). Six patients had posttraumatic instability, and 16 patients had congenital instability.
Twelve patients underwent placement of bilateral C1–2 transarticular screws, 6 patients had placement of a combination of C1–2 transarticular and C-2 pars screws, and 4 patients had placement of bilateral C-2 pars screws. One patient required a halo orthosis; the others were treated postoperatively with a hard cervical collar. All patients had radiographic evidence of solid occipitocervical arthrodesis on last follow-up examination.
The Wasatch loop system is a novel internal fixation device for children who have posttraumatic or congenital occipitocervical instability. Successful arthrodesis was achieved in all patients with minimal use of halo orthoses.
Wayne M. Gluf and Douglas L. Brockmeyer
Object. In this, the second of two articles regarding C1–2 transarticular screw fixation, the authors discuss their surgical experience in treating patients 16 years of age and younger, detailing the rate of fusion, complication avoidance, and lessons learned in the pediatric population.
Methods. The authors retrospectively reviewed 67 consecutive patients (23 girls and 44 boys) younger than 16 years of age in whom at least one C1–2 transarticular screw fixation procedure was performed. A total of 127 transarticular screws were placed in these 67 patients whose mean age at time of surgery was 9 years (range 1.7–16 years). The indications for surgery were trauma in 24 patients, os odontoideum in 22 patients, and congenital anomaly in 17 patients. Forty-four patients underwent atlantoaxial fusion and 23 patients underwent occipitocervical fusion. Two of the 67 patients underwent halo therapy postoperatively.
All patients were followed for a minimum of 3 months. In all 67 patients successful fusion was achieved.Complications occurred in seven patients (10.4%), including two vertebral artery injuries.
Conclusions. The use of C1–2 transarticular screw fixation, combined with appropriate atlantoaxial and craniovertebral bone/graft constructs, resulted in a 100% fusion rate in a large consecutive series of pediatric patients. The risks of C1–2 transarticular screw fixation can be minimized in this population by undertaking careful patient selection and meticulous preoperative planning.
Douglas L. Brockmeyer, Julie E. York and Ronald I. Apfelbaum
Craniovertebral instability is a challenging problem in pediatric spinal surgery. Recently, C1-2 transarticular screw fixation in pediatric patients has been used to assist in the stabilization of the craniovertebral joint. Currently there are no data that define the anatomical suitability of this technique in the pediatric population. The authors report their experience in 32 pediatric patients in whom craniovertebral instability was treated by placement of C1-2 transarticular screws.
From March 1991 to October 1998, 32 patients 16 years of age or younger with atlantooccipital, or atlantoaxial instability, or both were evaluated at our institution. There were 22 boys and 10 girls. Their ages ranged from 4 to 16 years (mean age 10.2 years). The most common causes of instability were os odontoideum (12 patients) and ligamentous laxity (nine patients). Six patients had undergone a total of nine previous attempts at posterior fusion at outside institutions.
All patients underwent extensive preoperative radiological evaluation including thin cut (1-mm) computerized tomography scanning with multiplanar reconstruction to evaluate the C1-2 joint space anatomy. Of the 64 possible C1-2 joint spaces in 32 patients, 55 sides (86%) were considered suitable for transarticular screw placement preoperatively. In three patients the C1-2 joint space anatomy was considered unsuitable for screw placement bilaterally. In three patients the anatomy was considered inadequate on one side. Fifty-five C1-2 transarticular screws were subsequently placed, with no resulting neurological or vascular complications. We conclude that C1-2 transarticular screw fixation is technically possible in a large proportion of pediatric patients with craniovertebral instability.
Jian Guan, Jay Riva-Cambrin and Douglas L. Brockmeyer
Patients treated for Chiari I malformation (CM-I) with posterior fossa decompression (PFD) may occasionally and unpredictably develop postoperative hydrocephalus. The clinical risk factors predictive of this type of Chiari-related hydrocephalus (CRH) are unknown. The authors' objective was to evaluate their experience to identify risk factors that may predict which of these patients undergoing PFD will develop CRH after surgery.
The authors performed a retrospective clinical chart review of all patients who underwent PFD surgery and duraplasty for CM-I at the Primary Children's Hospital in Utah from June 1, 2005, through May 31, 2015. Patients were dichotomized based on the need for long-term CSF diversion after PFD. Analysis included both univariate and multivariable logistic regression analyses.
The authors identified 297 decompressive surgeries over the period of the study, 22 of which required long-term postoperative CSF diversion. On multivariable analysis, age < 6 years old (OR 3.342, 95% CI 1.282–8.713), higher intraoperative blood loss (OR 1.003, 95% CI 1.001–1.006), and the presence of a fourth ventricular web (OR 3.752, 95% CI 1.306–10.783) were significantly associated with the need for long-term CSF diversion after decompressive surgery.
Younger patients, those with extensive intraoperative blood loss, and those found during surgery to have a fourth ventricular web were at higher risk for the development of CRH. Clinicians should be alert to evidence of CRH in this patient population after PFD surgery.