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Timothy J. Kovanda and Eric M. Horn

Secondary injury following initial spinal cord trauma is uncommon and frequently attributed to mismanagement of an unprotected cord in the acute time period after injury. Subacute posttraumatic ascending myelopathy (SPAM) is a rare occurrence in the days to weeks following an initial spinal cord injury that is unrelated to manipulation of an unprotected cord and involves 4 or more vertebral levels above the original injury. The authors present a case of SPAM occurring in a 15-year-old boy who sustained a T3–4 fracture-dislocation resulting in a complete spinal cord injury, and they highlight the imaging findings and optimum treatment for this rare event.

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Thomas J. Gianaris, Gregory M. Helbig, and Eric M. Horn

Object

Percutaneous pedicle screw insertion techniques are commonly used to treat a variety of spinal disorders. Typically, Kirschner (K)-wires are used to guide the insertion of taps and screws during placement since the normal anatomical landmarks are not visualized. The use of K-wires adds risks, such as vascular and nerve injuries as well as increased radiation exposure given the use of fluoroscopy. The authors describe a series of patients who had percutaneous pedicle screws placed using a new computer-assisted navigation technique without the need for K-wires.

Methods

Minimally invasive percutaneous pedicle screw placement in the thoracic and lumbar spine was performed in a consecutive series of 15 patients for a variety of spinal pathologies. Intraoperative 3D CT images were obtained and used with a computer-assisted navigation system to insert an awl-tap into each pedicle. The tap location in the pedicle was marked with the navigation software, and the awl-tap was then removed. The navigation system was used to identify each landmark to insert the pedicle screw. Connecting rods were then inserted percutaneously under fluoroscopic guidance. Postoperative CT scans were obtained in each patient to evaluate screw placement.

Results

On postprocedure scanning, only 1 screw had a minor lateral and superior breach that was asymptomatic. To date, there have been no hardware failures.

Conclusions

Percutaneous pedicle screws can be placed effectively and safely without the use of K-wires.

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Ryan P. Brennan, Philip Y. Smucker, and Eric M. Horn

Lower back pain from spondylolysis historically has been treated with a variety of options ranging from conservative care to open fusion. The authors describe the novel technique of minimally invasive bilateral pars interarticularis screw placement by utilizing intraoperative 3D imaging and frameless navigation in a 17-year-old male athlete. This technique is a modification of the open technique first described in 1970 by Buck and has the advantages of minimal dissection requirements with improved screw trajectory visualization. The patient's postoperative course is discussed, followed by a brief literature review of pars interarticularis defect treatment.

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Eric M. Horn, Peter Nakaji, Stephen W. Coons, and Curtis A. Dickman

Spinal meningeal melanocytomas are rare lesions that are histologically benign and can behave aggressively, with local infiltration. The authors present their experience with intramedullary spinal cord melanocytomas consisting of 3 cases, which represents the second largest series in the literature. A retrospective chart review was performed following identification of all spinal melanocytomas treated at the author's institution, based on information obtained from a neuropathology database. The charts were reviewed for patient demographics, surgical procedure, clinical outcome, and long-term tumor progression. Three patients were identified in whom spinal melanocytoma had been diagnosed between 1989 and 2006. The patients' ages were 37, 37, and 48 years, and the location of their tumor was C1–3, T9–10, and T-12, respectively. All 3 had complete resection with no adjuvant radiotherapy during follow-up periods of 16, 38, and 185 months, respectively. One patient demonstrated a recurrence 29 months after resection and the other 2 patients have demonstrated asymptomatic recurrences on imaging studies obtained at 16 and 38 months following resection.

With these cases added to the available literature, the evidence strongly suggests that complete resection is the treatment of choice for spinal melanocytomas. Even with complete resection, recurrences are common and close follow-up is needed for the long term in these patients. Radiation therapy should be reserved for those cases in which complete resection is not possible or in which there is recurrence.

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Neal B. Patel, Matthew A. Hazzard, Laurie L. Ackerman, and Eric M. Horn

Unstable pediatric cervical spine injuries present significant challenges in terms of fixation. Given the smaller cervical vertebral bodies in the preschool-aged population, commercially available pediatric cervical fixation instrumentation may be unsuitable because of the inappropriately large size of the screws and plates. The authors describe a 2-year-old girl who sustained an unstable C6–7 distraction injury during a motor vehicle accident. Because of the small size of her vertebral bodies, standard cervical spine instrumentation was not feasible, and posterior wiring alone was believed to be insufficient because of the complete distraction of all 3 spinal columns. The patient was taken to the operating room where craniofacial plates with an inherent locking mechanism were used to circumferentially stabilize the cervical spine. Follow-up examination 6 months postoperatively demonstrated stable cervical spine alignment and fusion with no evidence of the failure of either the anterior or posterior hardware. The use of craniofacial miniplates with an intrinsic locking mechanism represents a superior alternative for both anterior and posterior cervical fixations when spinal instrumentation is needed in the pediatric age group.

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Jeffrey F. Lastfogel, Thomas J. Altstadt, Richard B. Rodgers, and Eric M. Horn

Recent studies have demonstrated excellent results in treating isthmic spondylolisthesis via an anterior lumbar interbody fusion (ALIF). The authors describe 3 patients with isthmic spondylolisthesis at L5–S1 who experienced sacral fractures after insertion of a unique, stand-alone anterior interbody fixation device.

Three consecutive patients at a single institution were treated for Grade I spondylolisthesis at L5–S1 via a standalone ALIF with insertion of a novel biomechanical interbody device. This device is made of polyetheretherketone and has an integrated system for internal fixation into the vertebral bodies. In each patient a bone morphogenetic protein–soaked sponge was placed for the fusion. The indications for treatment in each patient were back and radicular pain that had been unsuccessfully treated with conservative measures.

All 3 patients had reduction of their spondylolisthesis and resolution of their unilateral radiculopathies immediately postoperatively. Within 1 month of surgery, all 3 patients had failure of the device and recurrence of their symptoms. In each case the failure was due to fracture of the anterior portion of the S-1 body. Each patient underwent reduction and pedicle screw fixation at L5–S1. In all cases, there was successful reduction in their recurrent spondylolisthesis and resolution of their radiculopathies.

Treatment of Grade I isthmic spondylolisthesis at L5–S1 with stand-alone ALIF and fixation can lead to sacral fracture from high stress loads at that level in the spine, and consideration should be made either for supplemental pedicle screw fixation or a completely posterior approach.

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Eric M. Horn, Jonathan S. Hott, Randall W. Porter, Nicholas Theodore, Stephen M. Papadopoulos, and Volker K. H. Sonntag

✓ Atlantoaxial stabilization has evolved from simple posterior wiring to transarticular screw fixation. In some patients, however, the course of the vertebral artery (VA) through the axis varies, and therefore transarticular screw placement is not always feasible. For these patients, the authors have developed a novel method of atlantoaxial stabilization that does not require axial screws. In this paper, they describe the use of this technique in the first 10 cases.

Ten consecutive patients underwent the combined C1–3 lateral mass–sublaminar axis cable fixation technique. The mean age of the patients was 62.6 years (range 23–84 years). There were six men and four women. Eight patients were treated after traumatic atlantoaxial instability developed (four had remote trauma and previous nonunion), whereas in the other two atlantoaxial instability was caused by arthritic degeneration. All had VA anatomy unsuitable to traditional transarticular screw fixation.

There were no intraoperative complications in any of the patients. Postoperative computed tomography studies demonstrated excellent screw positioning in each patient. Nine patients were treated postoperatively with the aid of a rigid cervical orthosis. The remaining patient was treated using a halo fixation device. One patient died of respiratory failure 2 months after surgery. Follow-up data (mean follow-up duration 13.1 months) were available for seven of the remaining nine patients and demonstrated a stable construct with fusion in each patient.

The authors present an effective alternative method in which C1–3 lateral mass screw fixation is used to treat patients with unfavorable anatomy for atlantoaxial transarticular screw fixation. In this series of 10 patients, the method was a safe and effective way to provide stabilization in these anatomically difficult patients.

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Iman Feiz-Erfan, Eric M. Horn, Harold L. Rekate, Robert F. Spetzler, Yu-Tze Ng, Jeffrey V. Rosenfeld, and John F. Kerrigan III

Object

The authors provide evidence that direct resection of hypothalamic hamartomas (HHs) can improve associated gelastic and nongelastic seizures.

Methods

Ten children younger than 17 years of age underwent resection of HHs (nine sessile and one pedunculated) that were causing refractory epilepsy. Lesions were approached from above transventricularly through a transcallosal anterior interforniceal approach in six cases, endoscopically through the foramen of Monro in one, and from below with a frontotemporal craniotomy including an orbitozygomatic osteotomy in three. Medical charts were reviewed retrospectively, and follow-up data were obtained through office records and phone calls.

Follow-up periods ranged between 12 and 84 months (mean 16.8 months). All patients in whom the approach was from above had sessile HHs. Five were free from seizures at follow up and two had a reduction in seizures of at least 95%. The transventricular route allowed excellent exposure and visualization of the local structures during resection. Among the three patients in whom the approach was from below, one became free of seizure after two procedures and one had a 75% reduction in epilepsy; the latter two had sessile HHs. The exposure was inadequate, and critical tissue borders were not readily apparent. Although the HH was adequately exposed and resected, the epilepsy persisted in the third patient, who had a pedunculated lesion. The overall rate of major permanent hypothalamic complications appeared to be slightly lower for the orbitozygomatic osteotomy group.

Conclusions

Sessile lesions are best approached from above. Approaches from below adequately expose pedunculated hamartomas. The likelihood of curing seizures seems to be higher when lesions are approached from above rather than from below.

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Eric M. Horn, Ruth E. Bristol, Iman Feiz-Erfan, Elisa J. Beres, Nicholas C. Bambakidis, and Nicholas Theodore

✓Pseudomeningoceles rarely develop after cervical trauma; in all reported cases the lesions have extended outside the spinal canal.

The authors report the first known cases of anterior cervical pseudomeningoceles contained entirely within the spinal canal and causing cord compression and neurological injury. The authors retrospectively reviewed the cases of three patients with traumatic cervical spine injuries and concomitant compressive anterior pseudomeningoceles. The lesion was recognized in the first case when the patient’s neurological status declined after he sustained a severe atlantoaxial injury; the pseudomeningocele was identified intraoperatively and decompressed. After the decompressive surgery, the patient’s severe tetraparesis partially resolved. In the other two patients diagnoses of similar pseudomeningoceles were established by magnetic resonance imaging. Both patients were treated conservatively, and their mild to moderate hemiparesis due to the pseudomeningocele-induced compression abated.

The high incidence of anterior cervical pseudomeningoceles seen at the authors’ institution within a relatively brief period suggests that this lesion is not rare. The authors believe that it is important to recognize the compressive nature of these lesions and their potential to cause devastating neurological injury.