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Cervical magnetic resonance imaging abnormalities not predictive of cervical spine instability in traumatically injured patients

Invited submission from the Joint Section Meeting on Disorders of the Spine and Peripheral Nerves, March 2004

Eric M. Horn, Gregory P. Lekovic, Iman Feiz-Erfan, Volker K. H. Sonntag and Nicholas Theodore

Object. Identifying instability of the cervical spine can be difficult in traumatically injured patients. The goal of this study was to determine whether cervical abnormalities demonstrated on magnetic resonance (MR) imaging are predictive of spinal instability.

Methods. Data in all patients admitted through the Level I trauma service at the authors' institution who had undergone cervical MR imaging were retrospectively reviewed. The reasons for MR imaging screening were neurological deficit, fracture, neck pain, and indeterminate clinical examination (for example, coma). Abnormal soft-tissue (prevertebral or paraspinal) findings on MR imaging were correlated with those revealed on computerized tomography (CT) scanning and plain and dynamic radiography to determine the presence/absence of cervical instability.

Of 6328 patients admitted through the trauma service, 314 underwent MR imaging of the cervical spine. Of 166 patients in whom CT scanning or radiography demonstrated normal findings, 70 had undergone MR imaging that revealed abnormal findings. Of these 70 patients, 23 underwent dynamic imaging, the findings of which were normal. In each case of cervical instability (65 patients) CT, radiographic, and MR imaging studies demonstrated abnormalities. Furthermore, there were 143 patients with abnormal CT or radiographic study findings, in 13 of whom MR imaging revealed normal findings. Six of the latter underwent dynamic testing, which demonstrated normal results.

Conclusions. Magnetic resonance imaging is sensitive to soft-tissue injuries of the cervical spine. When CT scanning and radiography detect no fractures or signs of instability, MR imaging does not help in determining cervical stability and may lead to unnecessary testing when not otherwise indicated.

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Skeletal dysplasia involving the subaxial cervical spine

Report of two cases and review of the literature

Gregory P. Lekovic, Nitin R. Mariwalla, Eric M. Horn, Steven Chang, Harold L. Rekate and Nicholas Theodore

✓ Because skeletal dysplasias are primary disorders of bone, they have not been commonly understood as neurosurgical diseases. Nevertheless, neurosurgical complications are commonly encountered in many cases of dysplasia syndromes. The authors present two cases of skeletal dysplasia that caused overt instability of the cervical spine. One patient with a diagnosis of Gorham disease of the cervical spine was treated with prolonged fixation in a halo brace after an initial attempt at instrumentation with a posterior occiput–C4 fusion. The other patient, who at birth was identified to have camptomelic dysplasia, has been treated conservatively from the outset. Although these two patients presented with different disorders—in one patient adequate mature bone never formed and in the other patient progressive bone loss became apparent after a seemingly normal initial development—these cases demonstrate unequivocally that surgical options for fusion are ultimately limited by the quality of the underlying bone. In patients in whom the bone itself is inadequate for use as a substrate for fusion, there are currently limited treatment options. Future improvements in our understanding of chondrogenesis and ossification may lead to the design of superior methods of encouraging fusion in these patients; however, at the present time, long-term maintenance in a halo brace may, in fact, be the only treatment.

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L. Fernando Gonzalez, Gregory P. Lekovic, Jennifer Eschbacher, Stephen Coons, Randall W. Porter and Robert F. Spetzler

✓Cavernous hemangiomas that occur within the cavernous sinus (CS) are different from cerebral cavernous malformations (CMs) clinically, on imaging studies, and in their response to treatment. Moreover, CMs are true vascular malformations, whereas hemangiomas are benign vascular tumors. Because of these differences, the authors suggest that these two entities be analyzed and grouped separately. Unfortunately, despite these differences, much confusion exists in the literature as to the nature, behavior, and classification of these two distinct lesions. This confusion is exacerbated by subtle histological differences and the inconsistent use of nomenclature. The authors use the term “cavernous malformation” to refer to intraaxial lesions only; they prefer to use the term “cavernous sinus hemangioma” to refer to extraaxial, intradural hemangiomas of the CS.

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Eric M. Horn, Nicholas Theodore, Iman Feiz-Erfan, Gregory P. Lekovic, Curtis A. Dickman and Volker K. H. Sonntag

Object

The risk factors of halo fixation in elderly patients have never been analyzed. The authors therefore retrospectively reviewed data obtained in the treatment of such cases.

Methods

A discharge database was searched for patients 70 years of age or older who had undergone placement of a halo device. In a search of cases managed between April 1999 and February 2005, data pertaining to 53 patients (mean age 79.9 years [range 70–97 years]) met these criteria. Forty-one patients were treated for traumatic injuries. Ten patients had deficits ranging from radiculopathy to quadriparesis, and 43 had no neurological deficit. Adequate follow-up material was available in 42 patients (mean treatment duration 91 days). Halo immobilization was the only treatment in 21 patients, and adjunctive surgical fixation was undertaken in the other 21 patients. There were 31 complications in 22 patients: respiratory distress in four patients, dysphagia in six, and pin-related complications in 10. Eight patients died; in two of these cases, the cause of death was clearly unrelated to the halo brace. The other six patients died of respiratory failure and cardiovascular collapse (perioperative mortality rate 14%). Three patients who died had sustained acute trauma and three had undergone surgical stabilization.

Conclusions

External halo fixation can be used safely to treat cervical instability in elderly patients. The high complication rate in this population may reflect the significant incidence of underlying disease processes.

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Eric M. Horn, Vivek R. Deshmukh, Gregory P. Lekovic and Curtis A. Dickman

✓ The management of spinal meningiomas with extensive involvement of the dura mater is controversial. The principal difficulty in performing a resection is the potential for complications associated with this approach. The authors present the case of a pregnant 35-year-old woman in whom bilateral lower-extremity numbness, weakness, gait ataxia, and myelopathy developed. Magnetic resonance imaging showed a recurrent thoracic meningioma with extensive infiltration of the dura mater. Durectomy, complete resection, and reconstruction were performed. The patient has not experienced a recurrence 21 months after her treatment. This case illustrates that thoracic spinal meningiomas with extensive dural involvement can be resected safely with a complete durectomy. The novel dural reconstruction involving the implantation of a fascia lata and bovine pericardium allograft is an effective way to reconstruct the dura to create an adequate barrier to cerebrospinal fluid.

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Gregory P. Lekovic, L. Fernando Gonzalez, Vini G. Khurana and Robert F. Spetzler

✓Although cavernous malformations (CMs) are an important cause of intracranial hemorrhage, the natural history of these lesions is controversial. Both retrospective and prospective studies undertaken to define risk factors for hemorrhage from CMs have consistently identified the location of a lesion as a factor that has a significant impact on the rate of rupture, and brainstem CMs consistently have a higher rate of symptomatic hemorrhage than those at other locations. The mechanism underlying this disparity in rupture rates, however, remains obscure. Most authors attribute the difference, at least partially, to the sensitivity of the brainstem to hemorrhage. Regardless, the specific factors that cause a given CM to rupture are unknown.

The authors report their first encounter with an intraoperative rupture of a CM in the brainstem. This case underscores the risks encountered during the surgical approach to brainstem CMs and may provide insight into the pathophysiological mechanisms underlying the rupture of these lesions.

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Eric M. Horn, Iman Feiz-Erfan, Gregory P. Lekovic, Curtis A. Dickman, Volker K. H. Sonntag and Nicholas Theodore

Object

Although rare, traumatic occipitoatlantal dislocation (OAD) injuries are associated with a high mortality rate. The authors evaluated the imaging and clinical factors that determined treatment and were predictive of outcomes, respectively, in survivors of this injury.

Methods

The medical records and imaging studies obtained in 33 patients with OAD were reviewed retrospectively. Clinical factors that predicted outcomes, especially neurological injury at presentation and imaging findings, were evaluated.

The most sensitive method for the diagnosis of OAD was the measurement of basion axial–basion dens interval on computed tomography (CT) scanning. Five patients with severe traumatic brain injuries (TBIs) were not treated and subsequently died. Of the 28 patients in whom treatment was performed, 23 underwent fusion and five were fitted with an external orthosis. Abnormal findings of the occipitoatlantal ligaments on magnetic resonance (MR) imaging, associated with no or questionable abnormalities on CT scanning, provided the rationale for nonoperative treatment. Of the 28 patients treated for their injuries, perioperative death occurred in five, three of whom had presented with severe neurological injuries. The mortality rate was highest in patients with a TBI at presentation. The mortality rate was lower in patients presenting with a spinal cord injury, but in this group there was a higher rate of persistent neurological deficits.

Conclusions

The spines in patients with CT-documented OAD are most likely unstable and need surgical fixation. In patients for whom CT findings are normal and MR imaging findings suggest marginal abnormalities, nonoperative treatment should be considered. The best predictors of outcome were severe brain or upper cervical injuries at initial presentation.

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Iman Feiz-Erfan, Eric M. Horn, Nicholas Theodore, Joseph M. Zabramski, Jeffrey D. Klopfenstein, Gregory P. Lekovic, Felipe C. Albuquerque, Shahram Partovi, Pamela W. Goslar and Scott R. Petersen

Object

Skull base fractures are often associated with potentially devastating injuries to major neural arteries in the head and neck, but the incidence and pattern of this association are unknown.

Methods

Between April and September 2002, 1738 Level 1 trauma patients were admitted to St. Joseph's Hospital and Medical Center in Phoenix, Arizona. Among them, a skull base fracture was diagnosed in 78 patients following computed tomography (CT) scans. Seven patients had no neurovascular imaging performed and were excluded. Altogether, 71 patients who received a diagnosis of skull base fractures after CT and who also underwent a neurovascular imaging study were included (54 men and 17 women, mean age 29 years, range 1–83 years). Patients underwent CT angiography, magnetic resonance angiography, or digital subtraction angiography of the head and craniovertebral junction, or combinations thereof.

Results

Nine neurovascular injuries were identified in six (8.5%) of the 71 patients. Fractures of the clivus were very likely to be associated with neurovascular injury (p < 0.001). A high risk of neurovascular injury showed a strong tendency to be associated with fractures of the sella turcica–sphenoid sinus complex (p = 0.07).

Conclusions

The risk of associated blunt neurovascular injury appears to be significant in Level 1 trauma patients in whom a diagnosis of skull base fracture has been made using CT. The incidence of neurovascular trauma is particularly high in patients with clival fractures. The authors recommend neurovascular imaging for Level 1 trauma patients with a high-risk fracture pattern of the central skull base to rule out cerebrovascular injuries.

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Gregory P. Lekovic, Eric A. Potts, Dean G. Karahalios and Graham Hall

Object

The goal of this study was to compare the accuracy of thoracic pedicle screw placement aided by two different image-guidance modalities.

Methods

The charts of 40 consecutive patients who had undergone stabilization of the thoracic spine between January 2003 and January 2005 were retrospectively reviewed. Three patients were excluded from the study because, on the basis of preoperative findings, small pedicle diameter precluded the use of pedicle screws. Thus, a total of 37 patients had 277 screws placed with the aid of either virtual fluoroscopy or isocentric C-arm 3D navigation. The indications for surgery included trauma, degenerative disease, and tumor, and were similar in both groups. All 37 patients underwent postoperative computed tomography scanning, and an independent reviewer graded all screws based on axial, sagittal, and coronal projections for a full determination of the placement of the screw in the pedicle.

Results

The rate of unintended perforations was found to depend on pedicle diameter (p < 0.0001). There were no statistical differences between groups with regard to rate or grade of cortical perforations. Overall, the rate and grade of perforations was low, and there were no neurological or vascular complications.

Conclusions

The authors have shown that either image-guidance system may be used with a high degree of accuracy and safety. Because both systems were found to be comparably safe and accurate, the choice of image-guidance modality may be determined by the level of surgeon comfort and/or availability of the system.

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Gregory P. Lekovic, L. Fernando Gonzalez, Andrew G. Shetter, Randall W. Porter, Kris A. Smith, David Brachman and Robert F. Spetzler

Object

Increasingly, radiosurgery is used to treat pineal region tumors, either as a primary treatment or as an adjunct to conventional radiation therapy. The authors report their experience with Gamma Knife surgery (GKS) for the treatment of pineal region tumors.

Methods

The authors retrospectively reviewed the charts of all patients undergoing GKS at their institution between 1997 and 2005. Seventeen patients underwent GKS for nonmetastatic tumors of the pineal region. All patients were treated using Leksell Gamma Plan treatment planning software (versions 4.12::5.34). The mean treatment volume was 7.42 cm3 (range 1.2–32.5 cm3). Prescribed doses ranged from 12 to 18 Gy. All doses were prescribed to the 50% isodose line. Independent neuroradiologists reviewed all follow-up imaging studies for evidence of progression of disease.

Results

One patient (Case 10) died 6 days after GKS. Mean clinical and imaging follow-up in the remaining 16 cases was 31 months. Local control was established during a mean neuroimaging follow-up period of 31 months (range 1–95) in 16 patients (100%). In 2 of these 16 patients (one with an anaplastic astrocytoma, the other with a primitive neuroectodermal tumor), leptomeningeal and spinal spread of tumor developed despite control of the pineal lesions. There were no new neurological deficits attributable to GKS. Three patients died (including the one who died 6 days after GKS) during the follow-up period.

Conclusions

Excellent control of pineal region brain tumors can be obtained with GKS when it is used in conjunction with surgery, conventional radiation therapy, or both. Patient survival and quality of life can be optimized through the use of multimodal treatment, including surgery, conventional radiation therapy and/or radiosurgery, and chemotherapy, when applicable.