During the last century the technological advances in the field of spinal surgery had a dramatic impact on the treatment of spinal deformity in children and adults. Before the advent of medications and vaccines to treat and/or prevent tuberculosis and poliomyelitis, patients suffering from these disorders often became incapacitated by the resulting kyphoscoliosis. In the early 1900s Lange began to address this problem mechanically by using foreign materials to stabilize the spine internally. In the 1950s and 1960s, owing to the efforts of Harrington and others, the process evolved to create the first generation of modern spinal instrumentation. The Harrington rod was able to correct a spinal deformity primarily through distraction. In the next wave of advances, some of the shortcomings of Harrington rods were addressed. Segmental fixation involving sublaminar wires was introduced in the 1970s by Luque. Anterior approaches and instrumentation-related techniques developed by Zielke and colleagues as well as Dywer and coworkers in the late 1960s and mid-1970s allowed for better correction of deformity with immobilization of fewer motion segments compared with posterior surgery. Transpedicular fixation of the spine was popularized by Cotrel and Dubousset in the 1980s; they used the technique to perform segmental stabilization, which better reduces the rotational aspect of a deformity. Finally, in the mid-1990s, thoracoscopic techniques were developed and are currently in use for anterior release and placement of instrumentation. The authors review the major technical developments for the surgical treatment of spinal deformity.
Avinash Lalith Mohan and Kaushik Das
Sumit Thakar, Avinash Kurudi Siddappa, Saritha Aryan, Dilip Mohan, Narayanam Anantha Sai Kiran and Alangar S. Hegde
The mesodermal derangement in Chiari Type I malformation (CMI) has been postulated to encompass the cervical spine. The objectives of this study were to assess the cross-sectional areas (CSAs) of cervical paraspinal muscles (PSMs) in patients with CMI without syringomyelia, compare them with those in non-CMI subjects, and evaluate their correlations with various factors.
In this retrospective study, the CSAs of cervical PSMs in 25 patients were calculated on T2-weighted axial MR images and computed as ratios with respect to the corresponding vertebral body areas. These values and the cervical taper ratios were then compared with those of age- and sex-matched non-CMI subjects and analyzed with respect to demographic data and clinicoradiological factors.
Compared with the non-CMI group, the mean CSA values for the rectus capitis minor and all of the subaxial PSMs were lower in the study group, and those of the deep extensors were significantly lower (p = 0.004). The cervical taper ratio was found to be significantly higher in the study cohort (p = 0.0003). A longer duration of symptoms and a steeper cervical taper ratio were independently associated with lower CSA values for the deep extensors (p = 0.04 and p = 0.03, respectively). The presence of neck pain was associated with a lower CSA value for the deep flexors (p = 0.03).
Patients with CMI demonstrate alterations in their cervical paraspinal musculature even in the absence of coexistent syringomyelia. Their deep extensor muscles undergo significant atrophic changes that worsen with the duration of their symptoms. This could be related to a significantly steeper cervical taper ratio that their cervical cords are exposed to. Neck pain in these patients is related to atrophy of their deep flexor muscles. A steeper cervical taper ratio and alterations in the PSMs could be additional indicators for surgery in patients with CMI without syringomyelia.
Leah Harburg, Jared B. Cooper, Allyson Flower, Michael E. Tobias and Avinash Mohan
Hemophagocytic lymphohistiocytosis (HLH) is a rare disease process characterized by aberrant immune system activation and an exaggerated inflammatory response. Establishing the diagnosis may be challenging and is achieved by satisfying a number of clinical criteria, in addition to demonstrating tissue hemophagocytosis. This syndrome is rapidly fatal if prompt diagnosis and treatment are not achieved. The authors present the case of a 17-year-old male patient with CNS HLH involving both the brain and spinal cord, highlighting the variable CNS manifestations in pediatric patients with HLH and the challenges that accompany establishing diagnosis.
D. Ryan Ormond, Ibrahim Omeis, Avinash Mohan, Raj Murali and Prithvi Narayan
✓ Cysts occupying the third ventricle are rare lesions and may appear as an unusual cause of obstructive hydrocephalus. Various types of lesions occur in this location, and they generally have an arachnoidal, endodermal, or neuroepithelial origin. The authors present a case of acute hydrocephalus following minor trauma in a child due to cerebrospinal fluid outflow obstruction by a third ventricular cyst. Definitive diagnosis of this cystic lesion was possible only with contrast ventriculography and not routine computed tomography or magnetic resonance imaging. The investigation, treatment, and pathological findings are discussed.
Robin M. Bowman, Avinash Mohan, Joy Ito, Jason M. Seibly and David G. McLone
All children born with a myelomeningocele at the authors' institution undergo aggressive treatment to maintain or improve functional outcome. Consequently, when any neurological, orthopedic, and/or urological changes are noted, a search for the cause is initiated. The most common cause of decline in a child born with a myelomeningocele is shunt malfunction. The second most common cause is tethering of the distal spinal cord at the site of the original back closure. In this report, the authors review the indicators of symptomatic spinal cord tethering and discuss the surgical interventions and outcomes in the children with myelomeningocele who underwent treatment at Children's Memorial Hospital from 1975 to 2008.
Among the 502 children who underwent original closure at Children's Memorial Hospital, a symptomatic tethered spinal cord developed in 114 (23%). Eighty-one patients (71%) have undergone 1 untethering procedure, and 33 patients (29%) have undergone multiple untetherings, for a total of 163 total surgeries. The indicators of symptomatic spinal cord tethering include scoliosis, decline in lower-extremity (LE) motor strength, LE contractures, LE spasticity, gait change, urinary changes, and pain.
Pain has shown the best response to surgical untethering, with 100% of children experiencing postoperative improvement. The results of long-term follow-up (average 12 years, range 1 month–23.3 years) in this cohort demonstrated scoliosis progression after surgical untethering in 52% of patients, with 28% requiring spinal fusion. On the 3-month postoperative manual muscle test, 70% of patients showed improved LE muscle strength compared to preoperatively. Gait was also similarly improved after untethering as evaluated by an orthopedic surgeon. Spasticity improved in two-thirds of the cohort, and as expected, LE contractures were stable (78%) postoperatively, as assessed by orthopedic and rehabilitation medicine specialists. Urologically, 64% of patients showed improvements on postoperative bladder evaluation.
Although this is a clinical outcome study with no control group, the authors' experience has been that tethered cord release is beneficial in maintaining neurological, urological, and orthopedic functioning in children born with a myelomeningocele.
Aaron R. Cutler, Saquib Siddiqui, Mohan Avinash L., Virany H. Hillard, Franco Cerabona and Kaushik Das
Transforaminal lumbar interbody fusion (TLIF) is an accepted alternative to circumferential fusion of the lumbar spine in the treatment of degenerative disc disease, spondylolisthesis, and recurrent disc herniation. To maintain disc height while arthrodesis takes place, the technique requires the use of an interbody spacer. Although titanium cages are used in this capacity, the two most common spacers are polyetheretherketone (PEEK) cages and femoral cortical allografts (FCAs). The authors compared the clinical and radiographic outcomes of patients who underwent TLIF with pedicle screw fixation, in whom either a PEEK cage or an FCA was placed as an interbody spacer.
The charts and x-ray films obtained in 39 patients (age range 33–68 years, mean 44.7 years) who underwent single-level TLIF between October 2001 and April 2004 and in whom either a PEEK cage (18 patients) or FCA (21 patients) was placed as an interbody spacer were evaluated in a retrospective study. Radiological outcome was based on fusion rate and a comparison of the initial postoperative lordotic angle on standing lateral radiographs with that at long-term follow up (mean follow up 15.1 months, minimum 12 months). To control for variations in radiographic magnification, the authors used lordotic angle as an indirect measure of disc space height. Clinical outcome was assessed using the Oswestry Disability Index (ODI).
There were no major complications in either group. Radiographically documented fusion occurred in all patients in the PEEK group and 95.2% of those in the FCA group. Pseudarthrosis developed in one patient in the FCA group, and this patient underwent additional surgery. In both groups, the mean lordotic angle changed by less than 2.20° during the postoperative period, and the mean postoperative ODI score was more than 40 points lower than the mean preoperative score. There was no significant difference between the two groups in mean change in lordotic angle (p = 0.415) and mean change in ODI score (p = 0.491).
Both PEEK cages and FCAs are highly effective in promoting interbody fusion, maintaining postoperative disc space height, and achieving desirable clinical outcomes in patients who undergo TLIF with pedicle screw fixation. The advantages of PEEK cages include a lower incidence of subsidence and their radiolucency, which permits easier visualization of bone growth.