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Mari L. Groves, Patricia L. Zadnik, Pablo F. Recinos, Violette Renard and George I. Jallo

The authors present a case of a 27-year-old patient who presented with spastic gait and worsening difficulty walking over a 6 month period. Spinal MR imaging revealed a heterogeneously enhancing intramedullary spinal cord tumor (IMSCT) with associated syrinx in the cervical spine. The lesion was resected through posterior en bloc laminotomy, durotomy, and microscopic resection of the intramedullary component followed by laminoplasty reconstruction. Surgical resections with a goal of gross total resection can significantly improve overall survival and progression free survival in patients with low-grade IMSCT. The procedure is presented in an edited, high-definition format with accompanying narrative.

The video can be found here: http://youtu.be/Ui9bn82PtP8.

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Joanna Y. Wang, Amir H. Dorafshar, Ann Liu, Mari L. Groves and Edward S. Ahn

OBJECTIVE

Because the metopic suture normally fuses during infancy, there are varying degrees of severity in head shape abnormalities associated with premature fusion. A method for the objective and reproducible assessment of metopic synostosis is needed to guide management, as current methods are limited by their reliance on aesthetic markers. The object of this study was to describe the metopic index (MI), a simple anthropometric cranial measurement. The measurements can be obtained from CT scans and, more importantly, from palpable cranial landmarks, and the index provides a rapid tool for evaluating patients in both pre- and postoperative settings.

METHODS

High-resolution head CT scans obtained in 69 patients (age range 0–24 months) diagnosed with metopic craniosynostosis were retrospectively reviewed. Preoperative 3D reconstructions were available in 15 cases, and these were compared with 3D reconstructions of 324 CT scans obtained in a control group of 316 infants (age range 0–24 months) who did not have any condition that might affect head size or shape and also in a subset of this group, comprising 112 patients precisely matched to the craniosynostosis patients with respect to age and sex. Postoperative scans were available and reviewed in 9 of the craniosynostosis patients at a mean time of 7.1 months after surgical repair. 3D reconstructions of these scans were matched with controls based upon age and sex.

RESULTS

The mean preoperative MI for patients with trigonocephaly was 0.48 (SD 0.05), significantly lower than the mean values of 0.57 (SD 0.04) calculated on the basis of all 324 scans obtained in controls (p < 0.001) and 0.58 (SD 0.04) for the subset of 112 age- and sex-matched controls (p < 0.001). For 7 patients with both pre- and postoperative CT scans available for evaluation, the mean postoperative MI was 0.55 (SD 0.03), significantly greater than their preoperative MIs (mean 0.48 [SD 0.04], p = 0.001) and comparable to the mean MI of the controls (p = 0.30). In 4 patients, clinically obtained postoperative MIs by caliper measurement were comparable to measurements derived from CT (p = 0.141).

CONCLUSIONS

The MI is a useful measurement of the severity of trigonocephaly in patients with metopic synostosis. This simple quantitative assessment can potentially be used in the clinical setting to guide preoperative evaluation, surgical repair, and postoperative degree of correction.

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Daniel J. Cognetti, Amer F. Samdani, Joshua M. Pahys, Mari L. Groves and Steven W. Hwang

Growing rod surgery for skeletally immature patients helps correct severe scoliosis while allowing continued spinal column growth. Previous reports have studied vertebral body changes following growing rod surgery, but there are currently no published reports on alterations in pedicle morphology. Given the potential need for definitive spinal fusion with pedicle screw instrumentation, an awareness of changes in pedicle morphology is critical. A morphometric analysis of pedicles was performed using 3D reconstructions of 3 CT scans (preoperative and at 3 and 6 years) obtained in a young girl with infantile idiopathic scoliosis (T7 apex) who underwent unilateral rib-to-spine growing rod (2nd–4th ribs to L1) implantation with lengthening every 6 months for 6 years. The pedicle widths on the growing rod side from T5 to T9 (apex ± 2) were all smaller at 6 years postoperatively than preoperatively, while the same-level pedicles opposite the device significantly increased in width. These findings support anecdotal intraoperative reports by surgeons and provide evidence of pedicle stress shielding due to growing rod distraction and force deprivation.

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Michelle J. Clarke, Patricia L. Zadnik, Mari L. Groves, Daniel M. Sciubba, Timothy F. Witham, Ali Bydon, Ziya L. Gokaslan and Jean-Paul Wolinsky

OBJECT

Recently, aggressive surgical techniques and a push toward en bloc resections of certain tumors have resulted in a need for creative spinal column reconstruction. Iatrogenic instability following these resections requires a thoughtful approach to adequately transfer load-bearing forces from the skull and upper cervical spine to the subaxial spine.

METHODS

The authors present a series of 7 cases in which lateral mass reconstruction with a cage or fibular strut graft was used to provide load-bearing support, including 1 case of bilateral cage placement.

RESULTS

The authors discuss the surgical nuances of en bloc resection of high cervical tumors and explain their technique for lateral mass cage placement. Additionally, they provide their rationale for the use of these constructs throughout the craniocervical junction and subaxial spine.

CONCLUSIONS

Lateral mass reconstruction provides a potential alternative or adjuvant method of restoring the load-bearing capabilities of the cervical spine.

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David S. Hersh, Rajiv R. Iyer, Tomas Garzon-Muvdi, Ann Liu, George I. Jallo and Mari L. Groves

OBJECTIVE

Spinal deformity has become a well-recognized complication of intramedullary spinal cord tumor (IMSCT) resection. In particular, laminectomy can result in biomechanical instability caused by loss of the posterior tension band. Therefore, laminoplasty has been proposed as an alternative to laminectomy. Here, the authors describe the largest current series of pediatric patients who have undergone laminoplasty for IMSCT resection and investigate the need for surgical fusion after both laminectomy and laminoplasty.

METHODS

The medical records of pediatric patients who underwent resection of an IMSCT at a single institution between November 2003 and May 2014 were reviewed retrospectively. Demographic, clinical, radiological, surgical, histopathological, and follow-up data were collected.

RESULTS

Sixty-six consecutive patients underwent resection of an IMSCT during the study period. Forty-three (65%) patients were male. The patients had a median age of 12.9 years (interquartile range [IQR] 7.2–16.5 years) at the time of surgery. Patients typically presented with a tumor that involved the cervical and/or thoracic spine. Nineteen (29%) patients underwent laminectomy, and 47 (71%) patients underwent laminoplasty. Patients in each cohort had a similar rate of postoperative deformity. Overall, 10 (15%) patients required instrumented spinal fusion for spinal deformity. Four patients required revision of the primary fusion.

CONCLUSIONS

These findings show that among pediatric patients with an IMSCT, postoperative surgical fusion rates remain high, even after laminoplasty. Known risk factors, such as the age of the patient, location of the tumor, and the number of involved levels, might play a larger role than replacement of the laminae in determining the rate of surgical fusion after IMSCT resection.

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Paul E. Kaloostian, Patricia L. Zadnik, Jennifer E. Kim, Mari L. Groves, Jean-Paul Wolinsky, Ziya L. Gokaslan, Timothy F. Witham, Ali Bydon and Daniel M. Sciubba

Pheochromocytomas of the spine are uncommon and require careful preoperative planning. The authors retrospectively reviewed the charts of 5 patients with metastatic spinal pheochromocytoma who had undergone surgical treatment over the past 10 years at their medical center. They reviewed patient age, history of pheochromocytoma resection, extent and location of metastases, history of alpha blockage, surgical level, surgical procedure, postoperative complications, tumor recurrence, and survival. Metastases involved the cervical (1 patient), thoracic (3 patients), and lumbar (2 patients) levels. Preoperative treatment included primary pheochromocytoma resection, chemotherapy, alpha blockade, embolization, and radiation. Three patients had tumor recurrence, and 2 underwent 2-stage reoperations for tumor extension. Hemodynamic complications were common: 2 patients developed pulseless electrical activity arrest within 4 months after surgery, 1 patient had profound postoperative tachycardia with fever and an elevated creatine kinase level, and 1 patient experienced transient postoperative hypotension and paraplegia. One patient died of complications related to disseminated cerebral and spinal disease.

With careful preoperative and surgical management, patients with symptomatic metastatic spinal pheochromocytoma can benefit from aggressive surgical treatment. Postoperative cardiovascular complications are common even months after surgery, and patients should be closely monitored long term.

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Patricia L. Zadnik, Camilo A. Molina, Rachel Sarabia-Estrada, Mari L. Groves, Michele Wabler, Jana Mihalic, Edward F. McCarthy, Ziya L. Gokaslan, Robert Ivkov and Daniel Sciubba

Object

The goal of this study was to optimize local delivery of magnetic nanoparticles in a rat model of metastatic breast cancer in the spine for tumor hyperthermia while minimizing systemic exposure.

Methods

A syngeneic mammary adenocarcinoma was implanted into the L-6 vertebral body of 69 female Fischer rats. Suspensions of 100-nm starch-coated iron oxide magnetic nanoparticles (micromod Partikeltechnologie GmbH) were injected into tumors 9 or 13 days after implantation. For nanoparticle distribution studies, tissues were harvested from a cohort of 36 rats, and inductively coupled plasma mass spectrometry and histopathological studies with Prussian blue staining were used to analyze the samples. Intratumor heating was tested in 4 anesthetized animals with a 20-minute exposure to an alternating magnetic field (AMF) at a frequency of 150 kHz and an amplitude of 48 kA/m or 63.3 kA/m. Intratumor and rectal temperatures were measured, and functional assessments of AMF-exposed animals and histopathological studies of heated tumor samples were examined. Rectal temperatures alone were tested in a cohort of 29 rats during AMF exposure with or without nanoparticle administration. Animal studies were completed in accordance with the protocols of the University Animal Care and Use Committee.

Results

Nanoparticles remained within the tumor mass within 3 hours of injection and migrated into the bone at 6, 12, and 24 hours. Subarachnoid accumulation of nanoparticles was noted at 48 hours. No evidence of lymphoreticular nanoparticle exposure was found on histological investigation or via inductively coupled plasma mass spectrometry. The mean intratumor temperatures were 43.2°C and 40.6°C on exposure to 63.3 kA/m and 48 kA/m, respectively, with histological evidence of necrosis. All animals were ambulatory at 24 hours after treatment with no evidence of neurological dysfunction.

Conclusions

Locally delivered magnetic nanoparticles activated by an AMF can generate hyperthermia in spinal tumors without accumulating in the lymphoreticular system and without damaging the spinal cord, thereby limiting neurological dysfunction and minimizing systemic exposure. Magnetic nanoparticle hyperthermia may be a viable option for palliative therapy of spinal tumors.

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Patricia L. Zadnik, C. Rory Goodwin, Kristophe J. Karami, Ankit I. Mehta, Anubhav G. Amin, Mari L. Groves, Jean-Paul Wolinsky, Timothy F. Witham, Ali Bydon, Ziya L. Gokaslan and Daniel M. Sciubba

OBJECT

Multiple myeloma is the most common primary tumor of the spine and is the most common primary malignant tumor of bone. Although spinal myeloma is classically a radiosensitive lesion, clinical or radiographic signs of instability merit surgical intervention. The authors present the epidemiology, surgical indications, and outcome data of a series of consecutive cases involving 31 surgically treated patients with diagnoses of multiple myeloma and plasmacytoma of the spine (the largest such series reported to date).

METHODS

Surgical instability was the criterion for operative intervention in this patient cohort. The Spinal Instability Neoplastic Score (SINS) was used to make this assessment of instability. The cases were analyzed using location of the lesion, spinal levels involved, Frankel score, adjuvant therapy, functional outcome, and patient survival.

RESULTS

All patients undergoing surgical intervention were determined to have indeterminate or gross spinal column instability according to SINS criteria. The median survival was 78.9 months. No significant difference in survival was seen for patients with higher SINS scores or for older patients (> 55 years). There was a statistically significant difference in survival benefit observed for patients receiving chemotherapy and radiation versus radiation alone as an adjuvant to surgery (p = 0.02).

CONCLUSIONS

In this 10-year analysis, the authors report outcomes of surgical intervention for patients with indeterminate or gross spinal instability due to multiple myeloma and plasmacytoma of the spine with improved neurological function following surgery and low rates of instrumentation failure.

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Michelle J. Clarke, Patricia L. Zadnik, Mari L. Groves, Hormuzdiyar H. Dasenbrock, Daniel M. Sciubba, Wesley Hsu, Timothy F. Witham, Ali Bydon, Ziya L. Gokaslan and Jean-Paul Wolinsky

Object

Traditionally, hemisacrectomy and internal hemipelvectomy procedures have required both an anterior and a posterior approach. A posterior-only approach has the potential to complete an en bloc tumor resection and spinopelvic reconstruction while reducing surgical morbidity.

Methods

The authors describe 3 cases in which en bloc resection of the hemisacrum and ilium and subsequent lumbopelvic and pelvic ring reconstruction were performed from a posterior-only approach. Two more traditional anterior and posterior staged procedures are also included for comparison.

Results

In all 3 cases, an oncologically appropriate surgery and spinopelvic reconstruction were performed through a posterior-only approach.

Conclusions

The advantage of a midline posterior approach is the ability to perform a lumbosacral reconstruction, necessary in cases in which the S-1 body is iatrogenically disrupted during tumor resection.

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Patricia Zadnik, Rachel Sarabia-Estrada, Mari L. Groves, Camilo Molina, Christopher Jackson, Edward McCarthy, Ziya L. Gokaslan, Ali Bydon, Jean-Paul Wolinsky, Timothy F. Witham and Daniel M. Sciubba

Object

Metastatic spine disease is prevalent in cancer victims; 10%–30% of the 1.2 million new patients diagnosed with cancer in the US exhibit spinal metastases. Unfortunately, treatments are limited for these patients, as disseminated disease is often refractory to chemotherapy and is difficult to treat with surgical intervention alone. New animal models that accurately recapitulate the human disease process are needed to study the behavior of metastases in real time.

Methods

In this study the authors report on a cell line that reliably generates bony metastases following intracardiac injection and can be tracked in real time using optical bioluminescence imaging. This line, RBC3, was derived from a metastatic breast adenocarcinoma lesion arising in the osseous spine of a rat following intracardiac injection of MDA-231 human breast cancer cells.

Results

Upon culture and reinjection of RBC3, a statistically significantly increased systemic burden of metastatic tumor was noted. The resultant spine lesions were osteolytic, as demonstrated by small animal CT scanning.

Conclusions

This cell line generates spinal metastases that can be tracked in real time and may serve as a useful tool in the study of metastatic disease in the spine.