Marc E Eichler

Harvard University, Cambridge, Massachusetts, United States

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Publications (5)21.66 Total impact

  • Jayshree Tuli · Sagun Tuli · Marc E Eichler · Eric J Woodard
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    ABSTRACT: In this paper, the authors compare the long-term outcomes of translaminar facet screw fixation (TFSF) and pedicle screw fixation (PSF) in the treatment of degenerative lumbosacral disease. This prospective analytical study was performed to compare the long-term outcomes of TFSF and PSF for degenerative lumbosacral disease. Outcomes were defined as the need for reoperation for the development of a nonunion, end-fusion degeneration, or for explantation of hardware. A total of 77 patients were analyzed. Thirty-seven patients underwent PSF and 40 received TFSF. Twenty-three of the 77 patients required a reoperation: 13 (32.5%) of the 40 patients in the TFSF group and 10 (27%) of the 37 the patients in the PSF group. The overall mean time to reoperation (regardless of outcome) was 4.05 years. For patients in the TFSF group the mean time to reoperation was 2.94 years, whereas it was 4.35 years in the PSF group (p = 0.34). Nonunion was noted in seven of the 40 patients in the TFSF group and one of 37 in the PSF group. The mean time to surgery for nonunion for patients in the TFSF group was 3.46 years and for those in the PSF group it was 6.27 years (p = 0.04). Surgery for end-fusion degeneration was performed in two patients in the TFSF group and five in the PSF group (p = 0.43). Explantation of hardware was performed in two patients with TFSF and four patients with PSF. Multivariable analysis revealed a statistically significant difference in the time to surgery for nonunion between PSF and TFSF (p = 0.048), with a hazard ratio of 0.097 (95% confidence interval 0.01-0.98). Findings from the current prospective study suggest that there is an increased risk of requirement for a reoperation for nonunion among TFSF cases compared with PSF cases.
    No preview · Article · Oct 2007 · Journal of Neurosurgery Spine
  • Sagun K Tuli · Marc E Eichler · Eric J Woodard
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    ABSTRACT: This retrospective study evaluated the perioperative morbidity of patients undergoing lumbar, sacral, or lumbosacral fusion using either pedicle or translaminar facet screw fixation following interbody fusion. Hospital charts of all patients who presented to a single tertiary care institution during a 4-year period were reviewed. Findings indicated translaminar facet screw fixation was a less invasive spinal fixation method with decreased perioperative morbidity compared to pedicle screw fixation.
    No preview · Article · Sep 2005 · Orthopedics
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    ABSTRACT: Respiratory dysfunction after cervical spinal cord injury (SCI) has not been examined experimentally using conscious animals, although clinical SCI most frequently occurs in midcervical segments. Here, we report a C5 hemicontusion SCI model in rats with abnormalities that emulate human post-SCI pathophysiology, including spontaneous recovery processes. Post-C5 SCI rats demonstrated deficits in minute ventilation (Ve) responses to a 7% CO2 challenge that correlated significantly with lesion severities (no injury or 12.5, 25, or 50 mm x 10 g weight drop; New York University impactor; p < 0.001) and ipsilateral motor neuron loss (p = 0.016). Importantly, C5 SCI resulted in at least 4 weeks of respiratory abnormalities that ultimately recovered afterward. Because serotonin is involved in respiration-related neuroplasticity, we investigated the impact of activating 5-HT1A receptors on post-C5 SCI respiratory dysfunction. Treatment with the 5-HT1A agonist 8-hydroxy-2-(di-n-propylmino)tetralin (8-OH DPAT) (250 microg/kg, i.p.) restored hypercapnic Ve at 2 and 4 weeks after injury (i.e., approximately 39.2% increase vs post-SCI baseline; p < or = 0.033). Improvements in hypercapnic Ve response after single administration of 8-OH DPAT were dose dependent and lasted for approximately 4 h(p < or = 0.038 and p < or = 0.024, respectively). Treatment with another 5-HT1A receptor agonist, buspirone (1.5 mg/kg, i.p.), replicated the results, whereas pretreatment with a 5-HT1A-specific antagonist, 4-iodo-N-[2-[4(methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinyl-benzamide (3 mg/kg, i.p.) given 20 min before 8-OH DPAT negated the effect of 8-OH DPAT. These results imply a potential clinical use of 5-HT1A agonists for post-SCI respiratory disorders.
    Full-text · Article · May 2005 · The Journal of Neuroscience : The Official Journal of the Society for Neuroscience
  • Sagun K Tuli · Peng Chen · Marc E Eichler · Eric J Woodard
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    ABSTRACT: Prospective assessment of the reliability of determining cervical fusion success based on plain radiographs. Determination of the reliability of plain static radiographs in predicting the presence or absence of fusion. The ability of plain radiographs to assess the presence of fusion is limited. In addition, variations in the definition of "fusion" make this entity an important aspect for study. A study was carried out to determine the reliability of plain radiographs in predicting bony fusion. Cases of cervical spondylosis undergoing a single or multilevel corpectomy with an allograft fusion and anterior instrumentation were chosen for the model. The definition of "bony fusion" was obtained from the literature. Bony fusion was defined by the presence of bony trabeculation across the graft-host interfaces, the assessment of the change in strut height over time, and the development of a kyphotic angulation over time. Data were collected at a tertiary care institution over a 5-year period. Descriptive statistics regarding baseline patient characteristics, the underlying disease process, and the surgical intervention, were obtained. Reliability of plain static radiographs in assessing fusion was evaluated by two independent neuroradiologists blinded to any subsequent clinical outcome. The Cohen Kappa statistic was used to determine the degree of agreement regarding the presence or absence of fusion at the superior and inferior aspect of the graft at the 6-week and the 12-week follow-up. The study involved 57 patients (30 males and 27 females), with a median age of 49 years. The number of levels decompressed was 1, 2, and 3 in 36, 20, and 1 patients, respectively. Fourteen patients had a history of smoking. The Cohen Kappa statistic revealed variable results depending on the time period and aspect evaluated. The degree of agreement at 6 weeks was 0.61 (95% confidence interval = 0.32-0.89) and 0.44 (95% confidence interval = 0.017-0.86) and at 12 weeks was 0.18 (95% confidence interval = -0.21-0.58) and 1.00 for the superior and inferior aspect of the graft, respectively. Plain radiographs are generally quite unreliable in predicting fusion based on presence or absence of trabeculation.
    No preview · Article · May 2004 · Spine
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    ABSTRACT: We investigated whether permeability transition-mediated release of mitochondrial cytochrome c is a potential therapeutic target for treating acute spinal cord injury (SCI). Based on previous reports, minocycline, a second-generation tetracycline, exerts neuroprotection partially by inhibiting mitochondrial cytochrome c release and reactive microgliosis. We first evaluated cytochrome c release at the injury epicenter after a T10 contusive SCI in rats. Cytochrome c release peaked at approximately 4-8 h postinjury. A dose-response study generated a safe pharmacological regimen that enabled i.p. minocycline to significantly lower cytosolic cytochrome c at the epicenter 4 h after SCI. In the long-term study, i.p. minocycline (90 mg/kg administered 1 h after SCI followed by 45 mg/kg administered every 12 h for 5 days) markedly enhanced long-term hind limb locomotion relative to that of controls. Coordinated motor function and hind limb reflex recoveries also were improved significantly. Histopathology suggested that minocycline treatment alleviated later-phase tissue loss, with significant sparing of white matter and ventral horn motoneurons at levels adjacent to the epicenter. Furthermore, glial fibrillary acidic protein and 2',3' cyclic nucleotide 3' phosphodiesterase immunocytochemistry showed an evident reduction in astrogliosis and enhanced survival of oligodendrocytes. Therefore, release of mitochondrial cytochrome c is an important secondary injury mechanism in SCI. Drugs with multifaceted effects in antagonizing this process and microgliosis may protect a proportion of spinal cord tissue that is clinically significant for functional recovery. Minocycline, with its proven clinical safety, capability to cross the blood-brain barrier, and demonstrated efficacy during a clinically relevant therapeutic window, may become an effective therapy for acute SCI.
    Full-text · Article · Apr 2004 · Proceedings of the National Academy of Sciences