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Biomedical subjects

S M Papadopoulos

Publications and source records attributed to S M Papadopoulos.

At least 37 records · Page 2Linked to original sources
PubMed1994

Outcome after laminectomy for lumbar spinal stenosis. Part I: Clinical correlations.

All patients who underwent decompressive lumbar laminectomy in the Washtenaw County, Michigan metropolitan area during a 7-year period were studied for the purpose of defining long-term outcome, clinical correlations, and the need for subsequent fusion. Outcome was determined by questionnaire and physical examination from a cohort of 119 patients with an average follow-up evaluation interval of 4.6 years. Patients graded their outcome as much improved (37%), somewhat improved (29%), unchanged (17%), somewhat worse (5%), and much worse (12%) compared to their condition before surgery. Poor outcome correlated with the need for additional surgery, but there were few additional significant correlations. No patient had a lumbar fusion during the study interval. The outcome after laminectomy was found to be less favorable than previously reported, based on a patient questionnaire administered to an unbiased patient population. Further randomized, controlled trials are therefore necessary to determine the efficacy of lumbar fusion as an adjunct to decompressive lumbar laminectomy.

Adult↗
PubMed1994

Outcome after laminectomy for lumbar spinal stenosis. Part II: Radiographic changes and clinical correlations.

The pre- and postoperative lumbar spine radiographs of 119 patients who underwent decompressive lumbar laminectomy were studied to evaluate radiographic changes and to correlate them with clinical outcome. An accurate and reproducible method was used for measuring pre- and postoperative radiographs that were separated by an average interval of 4.6 years. Levels of the spine that underwent laminectomy showed greater change in spondylolisthesis, disc space angle, and disc space height than unoperated levels. Outcome correlated with radiographic changes at operated and unoperated levels. This study demonstrates that radiographic changes are greater at operated than at unoperated levels and that some postoperative symptoms do correlate with these changes. Lumbar fusion should be considered in some patients who undergo decompressive laminectomy. The efficacy of and unequivocal indications for lumbar fusion can only be determined from randomized, prospective, controlled trials, however, and these studies have not yet been undertaken.

Age Factors↗
PubMed1993

Traumatic occipitoatlantal dislocations.

Fourteen occipitoatlantal dislocations were treated during an 11-year period. All patients presented with neurological deficits and definite evidence of spinal instability. Plain radiographs provided the diagnosis conclusively in 11 patients. Three patients required computed tomography (CT) or magnetic resonance (MR) imaging for diagnosis. Rotational subluxations were radiographically occult and associated with less severe neurological injuries compared to distracted or translated subluxations. Ten patients died acutely. One patient, who had complete C1 level quadriplegia, died after 3 months. Three patients with incomplete spinal cord syndromes had long-term survival and functional neurological recoveries. Extensive ligamentous injury predisposed patients to recurrent subluxations. In several patients, traction or a cervical collar caused distraction and neurological injury. Halo immobilization and urgent fusion are necessary for patients with salvageable neurological function. Nonoperative measures are inadequate for immediate or long-term spinal stability.

Accidents, Traffic↗
PubMed1993

Magnetic resonance imaging documentation of coexistent traumatic locked facets of the cervical spine and disc herniation.

The coexistence of traumatic locked facets of the cervical spine and a herniated disc is not well described. The authors present a series of patients with traumatic locked facets who demonstrated a high incidence of associated disc herniation documented on magnetic resonance (MR) imaging. Thirteen patients with either unilateral (four cases) of bilateral (nine cases) locked facets of the cervical spine were analyzed retrospectively. Immediate closed reduction using traction and/or manipulation was attempted in the first nine cases treated and was successful in only three; however, the procedure was abandoned in three cases due to deterioration in the patient's clinical status. In the subsequent four patients, an MR image was obtained prior to attempts at closed reduction. All patients underwent MR imaging of the cervical spine. Of eight consecutive cases treated at the University of Michigan, frank disc herniation with fragmented disc in the canal was found in five while pathological disc bulging was found in the other three. All five cases contributed by other institutions had concurrent disc herniation. This series illustrates the importance of using MR imaging to document the presence of a herniated disc during the initial evaluation of a patient with traumatic locked facets of the cervical spine and prior to attempted reduction of the locked facets. Experience indicates that closed reduction of facet dislocation associated with disc rupture may result in increased spinal cord compression and neurological deficit. If a herniated disc is discovered, anterior discectomy and fusion would be favored as the initial therapy over attempts at closed reduction or operative posterior reduction.

Adolescent↗
PubMed1993

Neurogenic hypertension related to basilar impression. Case report.

The authors report the resolution of essential hypertension following transoral odontoidectomy and medullary decompression in a 39-year-old woman with basilar invagination. Current understanding of central regulation of the cardiovascular system is discussed and the pertinent neuroanatomy illustrated. Experimental and clinical evidence supporting the role of neurogenic mechanisms in the pathogenesis of hypertension is reviewed.

Adult↗
PubMed1993

Lumbar disk disease: pathophysiology, management and prevention.

Patients with symptomatic lumbar disk disease may present with back pain, referred leg pain, radicular leg pain, sensory changes and leg weakness. Because neurologic deficits are commonly localized to the L5 or S1 nerve roots, evaluation of patients with such symptoms should focus on these dermatomes and muscle groups. Myelography, computed tomography, postmyelogram computed tomography and magnetic resonance imaging are the most valuable diagnostic studies. Initial management consists of physical therapy and reduced activity, followed by gradually increasing mobilization and exercise. Conservative treatment is effective for most patients. Surgical treatment is reserved for patients who have failed to improve with conservative therapy or those who present with a profound neurologic deficit. Prevention of recurrent symptoms centers on patient education and reassurance. A program of weight control, regular exercise and posture correction may reduce the frequency and severity of recurrent disk herniation and pain.

Humans↗
PubMed1992

Oscillatory contractions in vertebral arteries from hypertensive subjects.

In response to several agonists, tail arteries from spontaneously hypertensive stroke prone rats (SHRSP) contract in an oscillatory manner not observed in tail arteries from normotensive rats. This study evaluated whether oscillations in force development characterize the contractile pattern of vertebral arteries from hypertensive humans. Vertebral arteries were isolated and studied within 18-24 h post mortem. Helical strips of the arteries were mounted in a muscle bath for isometric force recording. Contractile responses to serotonin (10(-7)M) and endothelin (10(-8)M) in arteries from hypertensive subjects were characterized by fluctuations in force development whereas those in arteries from normotensive subjects usually remained constant with time. The frequency of the response was approximately 1-2 contraction/relaxation cycles per min. This pattern of oscillatory contractile activity was observed in all but one of the hypertensive arteries (n = 15), and in approximately 40% of the normotensive arteries (n = 12). Oscillatory activity was converted to maintained contraction by nifedipine (10(-7)M) which also caused relaxation of the contractile response. Relaxation to acetylcholine (10(-6)M) and nitroglycerin (10(-6)M) did not alter the oscillatory contractions. Endothelium removal did not influence the oscillatory pattern of contraction. These observations suggest that oscillatory contractile activity in vertebral arteries from hypertensive subjects is related to abnormal calcium entry into the smooth muscle cells. This altered membrane property may contribute to changes in vascular reactivity in hypertension.

Aged↗
PubMed1992

Spinal cord astrocytomas: results of therapy.

Spinal cord astrocytomas are rare lesions, usually of low grade, with a long natural history. Because of this, it is difficult to define the optimum approach to therapy based on available data. To provide more data, a retrospective review was performed. From 1975 through 1989, 21 patients were seen and treated (median age, 21 years), and 15 patients received radiation therapy after undergoing either biopsy or resection. The median time until death or the last follow-up examination was 41 months. The actuarial survival of all patients was 68% at 5 years. Of the five deaths, four were related to local tumor recurrence. The overall survival and recurrence-free survival of irradiated patients at 5 years was 57% and 44%, respectively. The age of the patient was a prognostic factor, with younger patients surviving substantially longer before recurrence. Of the 15 irradiated patients, 7 experienced recurrence of the tumor, which occurred within the irradiated portion of the spinal cord in all 7. Gross total resections were rarely achieved and, also, the extent of resection did not influence the risk for recurrence. In summary, we observed a long natural history for this disease, and although additional local therapy appears needed, it is unclear that either higher doses of radiation or more extensive surgery will decrease the risk of recurrence.

Actuarial Analysis↗
PubMed1992

Technetium-99m-N1-(2-mercapto-2-methylpropyl)-N2-(2-propargylthio-2- methylpropyl)-1,2-benzenediamine (T691): preclinical studies of a potential new tracer of regional cerebral perfusion.

We report in vitro and in vivo preclinical studies of a new cerebral blood flow tracer, [99mTc]N1-(2-mercapto-2-methyl-propyl)-N2-(2- propargylthio-2-methylpropyl)-1,2-benzenediamine (T691). The tracer demonstrates excellent in vitro chemical stability and accumulates regionally in the brain in a pattern consistent with that of cerebral blood flow. First-pass cerebral extraction determined with the use of the brain uptake index method in the rat was 0.76. Bolus intracarotid injection in monkeys indicated a cerebral extraction of 68% and prolonged retention of 67% of the initially extracted activity. Autoradiographic studies in rats revealed a pattern characteristic of cerebral blood flow at both 1 and 60 min after systemic injection. Dynamic tomographic imaging following systemic injection in the monkey revealed peak brain activity 1 to 2 min postinjection, without significant decline over 60 min. Chromatographic studies of brain as long as 60 min following systemic injection of [99mTc]T691 showed no evidence of tracer metabolism to account for its retention. Overall, [99mTc]T691 demonstrates promise as a potential new clinical tracer of cerebral perfusion.

Animals↗
PubMed1992

Spinal cord injury.

Continued investigation of the pathophysiology of primary and secondary neuronal injury following acute spinal cord injury (SCI) has led to positive results in two medical treatment protocols: methylprednisolone and GM1 ganglioside. The advent of improved high resolution radiologic studies has allowed a new dimension in the understanding of the physical and pathomechanical aspects of acute SCI. Advances in rehabilitation continue, allowing improved prognosis and long-term function. Prevention is clearly the best and most effective treatment of all.

G(M1) Ganglioside↗
PubMed1992

Caspar plate fixation for the treatment of complex hangman's fractures.

This report details our recent experience with the surgical treatment of complex hangman's fractures after failure of closed reduction and immobilization in external orthosis. We have successfully treated hangman's fractures in 5 patients with anterior Caspar plate stabilization and C2-C3 interbody fusion. The specific anatomical features of these fractures were complex, rendering the spines of the patients highly unstable. The patients were considered surgical candidates when reduction could not be achieved or maintained with axial traction or halo immobilization. Each patient underwent anterior C2-C3 interbody bone fusion and Caspar plating from C2 to C3. All patients achieved adequate intraoperative reduction and were immobilized postoperatively with a halo vest. The follow-up period ranged from 3 to 28 months and provided a 100% fusion rate with no complications related to plating or nonunion. Our initial experience indicates that anterior C2-C3 interbody bone fusion and Caspar plate fixation is a suitable treatment option for patients with complex hangman's fractures who are not successfully managed nonoperatively.

Adolescent↗
PubMed1991

Traumatic atlantooccipital dislocation with survival.

Survival after traumatic atlantooccipital dislocation is rare. Only long-term survivors have been reported in the literature; however, improved prehospital care is likely responsible for the increase in the number of these patients seen at neurotrauma centers over the last decade. Associated severe and persistent neurological deficits are common in the few survivors. We report the case of a 10-year-old boy with traumatic atlantooccipital dislocation and a severe neurological injury. Low-field magnetic resonance imaging provided the additional diagnosis of an associated cervicomedullary epidural hematoma. The patient underwent emergency operative evacuation of the hematoma and an occipital-cervical fusion with internal fixation. He had a remarkable recovery in neurological function and achieved stable bony fusion 3 months postoperatively. With early recognition of this entity, improved neuroradiological imaging techniques, and aggressive treatment, patients may survive with significant neurological recovery.

Atlanto-Occipital Joint↗
PubMed1991

Atlantoaxial stabilization in rheumatoid arthritis.

Atlantoaxial subluxation in patients with rheumatoid arthritis is common. Operative stabilization is clearly indicated when signs and symptoms of spinal cord compression occur. However, many recommend early operative fusion before evidence of appreciable neural compression occurs because 1) the myelopathy in these patients may be irreversible; 2) the overall prognosis is poor once symptoms of cord compression are present; and 3) the risk of sudden death associated with atlantoaxial subluxation is increased even in asymptomatic patients. The authors believe that rheumatoid arthritis patients in relatively good health without advanced multisystem disease and less than 65 years of age should be considered for operative stabilization if mobile atlantoaxial subluxation is greater than 6 mm. Seventeen patients with severe rheumatoid arthritis and atlantoaxial subluxation treated with a posterior arthrodesis are presented. A new method of fusion, devised by the senior author (V.K.H.S.), was utilized in all cases. Indications for operative therapy in these patients included evidence of spinal cord compression in 11 patients (65%) and mobile atlantoaxial subluxation greater than 6 mm but no signs or symptoms of cord compression in six patients (35%). Thirteen patients developed a stable osseous fusion, two patients a well-aligned fibrous union, one patient a malaligned fibrous union, and one patient died prior to evaluation of fusion stability. The details of the operative technique and management strategies are presented. Several technical advantages of this method of fusion make this approach particularly useful in patients with rheumatoid arthritis. Because of multisystem involvement of this disease, a high rate of osseous fusion is often difficult to achieve.

Adult↗
PubMed1991

The interspinous method of posterior atlantoaxial arthrodesis.

Thirty-six patients underwent C1-2 posterior wiring and fusion procedures over a 5-year period for unstable C-2 fractures (eight cases), unstable atlas-axis combination fractures (six cases), rheumatoid C1-2 instability (14 cases), os odontoideum (four cases), traumatic C1-2 ligamentous instability (three cases), or instability secondary to a C-2 tumor (one case). In each case, the atlantoaxial arthrodesis utilized sublaminar wire at C-1 and incorporated an iliac-crest strut-graft positioned between the posterior arches of C-1 and C-2, held in place by securing wire around the base of the spinous process of the axis. Follow-up examination was performed in all patients after a mean postoperative duration of 33.7 months. The technical aspects and clinical merits of this fusion procedure, which led to a 97% union rate (one nonunion) and minimal morbidity and mortality rates, are presented.

Adult↗
PubMed1991

Phase I trial of tissue plasminogen activator for the prevention of vasospasm in patients with aneurysmal subarachnoid hemorrhage.

Recent laboratory studies have demonstrated that intracisternal administration of recombinant tissue plasminogen activator (rt-PA) can facilitate the normal clearing of blood from the subarachnoid space and prevent or ameliorate delayed arterial spasm. The results of a preliminary Phase I trial of intracisternal rt-PA in 10 patients are reported with documented aneurysmal subarachnoid hemorrhage (SAH). All patients enrolled were classified as clinical Grade III or IV (according to Hunt and Hess) with thick clots or layers of blood in the basal cisterns and major cerebral fissures (Fisher Grade 3). Ventriculostomy and surgery for clipping of the aneurysms were performed within 48 hours of hemorrhage. In one patient, 10 mg rt-PA was instilled into the subarachnoid cisterns prior to closing the dura. In the remaining nine patients, a small silicone catheter was left in the subarachnoid space and rt-PA (5 mg in four cases or 1.5 mg (0.5 mg every 8 hours for three infusions) in five cases) was instilled 12 to 24 hours after surgery. Minor local bleeding complications were noted in all patients receiving 5 or 10 mg rt-PA. Oozing was noted at the operative incision site in four of five patients and at the ventriculostomy site in two patients. One patient developed a small epidural hematoma that was treated by delayed drainage. No bleeding complications were noted in the patients receiving the lower regimen of rt-PA (three infusions of 0.5 mg each). Serial coagulation studies demonstrated no evidence of systemic fibrinolysis. Analysis of cisternal cerebrospinal fluid samples revealed thrombolytic tissue plasminogen activator (t-PA) levels for 24 to 48 hours. Follow-up cerebral angiography 7 to 8 days after rupture disclosed mild to moderate spasm in nine patients, while one patient with hemorrhage from a posterior inferior cerebellar artery aneurysm had severe focal spasm of the vertebral arteries that was not symptomatic. These results suggest that postoperative treatment with rt-PA may be effective in reducing the severity of delayed cerebral vasospasm. The results of serial t-PA levels suggest that the lower dosage regimen with divided dosages at 8-hour intervals is well tolerated and that even lower dosages may be effective. Further studies are clearly indicated.

Adult↗
PubMed1991

Metastatic epidural spinal cord compression.

It is important to remember that ESCC is a complication of systemic malignancy and usually denotes disseminated disease with poor survival rates. Early diagnosis is crucial. The initial symptom is almost always back pain, which is local, radicular, or both. Following neurologic examination and radiography, MRI scanning or myelography/CT is immediately indicated if radiculopathy or myelopathy is present or if the radiographs of the spine are abnormal. In cancer patients with local back pain and normal findings on neurologic examination and radiography of the spine, there is still a probability of 0.1 of significant ESCC. Therefore, urgent CT/MRI scanning is justified. At present, the best treatment for ESCC remains unknown. In the majority of patients, radiotherapy is the most readily available and appropriate option because it is equal in effect to posterior decompressive laminectomy in both radiosensitive and radioresistant tumors. In patients with posterior epidural disease without tissue diagnosis, laminectomy with or without stabilization should be performed. Posterior decompressive laminectomy alone is contraindicated in patients with vertebral collapse. In selected instances of anterior epidural compression without tissue diagnosis or after failure of radiotherapy, an anterior surgical approach or synchronous vertebral decompression with posterior stabilization may be indicated. In the future, after appropriate clinical trials, vertebral body resection may be the optimal approach in de novo selected patients with ESCC with radioresistant tumors and limited systemic spread of the disease.

Combined Modality Therapy↗