Biomedical subjects

K H Bridwell

Publications and source records attributed to K H Bridwell.

At least 19 recordsLinked to original sources

PubMed1992

Analysis of pulmonary function and axis rotation in adolescent and young adult idiopathic scoliosis patients treated with Cotrel-Dubousset instrumentation.

Forty-eight patients with idiopathic scoliosis underwent posterior spinal fusion with Cotrel-Dubousset instrumentation (CDI). Each patient was given preoperative and postoperative pulmonary function tests (PFTs). Pulmonary volume improved a mean 0.40 L (16%), and pulmonary flow improved a mean 0.33 L (15%). Differences between preoperative and postoperative PFT values were shown to be statistically significant and correlated well with coronal side-bending correction. Twenty patients had preoperative and postoperative CT scans through the apical vertebra. Vertebral rotation was assessed on CT scan by the method of Aaro and Dahlborn (1,2). At the apex, the mean percentage improvements in the longitudinal axis rotation relative to the midline (16%) and to the sagittal plane (10%), the rib hump index (8%), and the kyphosis-lordosis index (0%) were minimal. Radiographically, the 66% mean improvement in apical vertebral translation was more substantial and consistent than the 10% mean improvement in apical vertebral rotation. Therefore, at the apex the CDI "derotation maneuver" may be more of a "translational maneuver."

Adolescent↗

PubMed1992

Results of in situ fusion for isthmic spondylolisthesis.

Between 1976 and 1990, we treated 56 isthmic spondylolisthesis patients with an average age of 15 + 4 (range, 4 + 9 to 27 +/- 2) with in situ bilateral transverse process fusions utilizing autogenous iliac bone graft. None of the patients had a decompression or instrumentation placed. Radiographic fusion was determined from standing spot lateral radiographs and either Ferguson AP or standing AP views of the lumbosacral junction. The radiographic fusion patterns were categorized into the following four grades: (A) definitely solid (n = 28, 50%)--solid big trabeculated bilateral fusion masses; (B) possibly solid (n = 10, 18%)--unilateral large fusion mass with contralateral small fusion mass; (C) probably not solid (n = 6, 11%)--small, thin fusion masses bilaterally; (D) definitely not solid (n = 12, 21%)--graft resorption bilaterally or fusion mass with obvious bilateral pseudarthrosis. This fusion pattern is best determined by the Ferguson ("true AP") radiograph of the lumbosacral junction. Despite this surprisingly low fusion rate, overall clinical improvement was noted in > 80% of patients with preoperative symptoms of back pain, leg pain, or hamstring tightness. We recommend this critical assessment of fusion grades to determine fusion success in this patient population.

Adolescent↗

PubMed1992

Preventing decompensation in King type II curves treated with Cotrel-Dubousset instrumentation. Strict guidelines for selective thoracic fusion.

Between 1985 and 1988, 50 adolescent idiopathic scoliosis patients with either King Type II (n = 19) or III (n = 31) curves were treated with Cotrel-Dubousset instrumentation and had a minimum of 2-year follow-up. Five of these patients had early postoperative decompensation, and have provided important lessons for the future prevention and treatment of these imbalances. Most problematic was distinguishing between King Type II and double major curve patterns. Proper identification of King Type II curves, which may be successfully treated with selective thoracic fusion, requires careful analysis of the standing preoperative coronal radiograph as well as the side benders. Thus, we now define Type II curves based on the differential between the thoracic and lumbar curve magnitude, apical vertebral deviation from the midline, and apical vertebral rotation on the standing coronal radiograph in addition to a positive flexibility index.

Adolescent↗

PubMed1992

Effects of distraction on physiologic integrity of the spinal cord, spinal cord blood flow, and clinical status.

The authors determined the effects of distraction of the spine on physiologic integrity of the spinal cord using neurogenic motor evoked potentials (NMEPs), somatosensory evoked potentials (SEPs), spinal cord blood flow measurements, and clinical status in nine hogs. Spinal cord blood flow was measured after each level of distraction using the hydrogen washout technique. The results indicated that blood flow of at least 65% of baseline was required to maintain physiologic integrity of the spinal cord, and that a decrease of blood flow to 12% of baseline was associated with paraplegia. Neurogenic motor evoked potentials always correlated with the animal's postsurgical clinical status, whereas the SEP was falsely negative in one animal.

Animals↗

PubMed1992

Cotrel-Dubousset instrumentation for adolescent idiopathic scoliosis.

We evaluated the results of segmental fixation of the spine with Cotrel-Dubousset instrumentation in ninety-five patients who had adolescent idiopathic scoliosis. The instrumentation was used in an attempt to achieve three-dimensional correction of the scoliosis, maintain lumbar lordosis, create thoracic kyphosis, and avoid the need for a postoperative cast or brace. The patients were followed for twenty-four to sixty-four months (average, thirty-five months). Cotrel-Dubousset instrumentation provided an average correction of the coronal curve of 48 per cent at the time of the most recent follow-up. The normal sagittal curves at the thoracolumbar junction and in the lumbar spine were maintained, and the thoracic kyphosis was increased slightly (average, +7 degrees). Apical translation improved an average of 60 per cent, and apical rotation improved an average of 11 per cent. Forced vital capacity improved an average of 21 per cent, and the one-second forced expiratory volume improved an average of 18 per cent. There were no major neurological deficits. A symptomatic pseudarthrosis developed in one patient. Postoperatively, decompensation of the spine developed in five of the first twenty-six patients who had a Type-II or Type-III curve. This complication was avoided in the last twenty-four patients who had a Type-II or Type-III curve by means of a stricter adherence to the definition of a Type-II curve, and reversal of the bend of the rod and the hooks between the caudal neutral and stable vertebrae. The major advantages of Cotrel-Dubousset instrumentation are the stable fixation that is achieved and the preservation of segmental lumbar lordosis.

Adolescent↗

PubMed1991

Clinical correlation between degenerative spine disease and dermatomal somatosensory-evoked potentials in humans.

The relationship between clinical status and preoperative and intraoperative dermatomal somatosensory-evoked potentials was investigated as a function of test site. Results indicated that the specificity and sensitivity of dermatomal somatosensory-evoked potentials varied with level of involvement: L5 demonstrated greatest agreement with equal correlation at L3, L4, and S1. Variables that influenced correlation included history of previous surgeries, type of anesthetic used, interpretation criteria, and whether the patient was awake or asleep. It was concluded that dermatomal somatosensory-evoked potentials can provide the surgeon with diagnostic and intraoperative information regarding the functional integrity of single nerve root function.

Evoked Potentials, Somatosensory↗

PubMed1991

Coronal decompensation produced by Cotrel-Dubousset "derotation" maneuver for idiopathic right thoracic scoliosis.

From 1985 to 1987, 82 patients with idiopathic scoliosis followed 12 to 44 months underwent selective fusion and correction of their right thoracic curves by Cotrel-Dubousset instrumentation using the "derotation" maneuver. Preoperative, postoperative, and follow-up standing anteroposterior roentgenograms of the spine were analyzed. For curves in which there was deviation from the midline (plumb line) and rotation of the lumbar segments, an increased incidence of decompensation was produced after surgery, when posterior Cotrel-Dubousset instrumentation and fusion were carried to the "stable" vertebra with one rod bend and hook alignment on the left sided derotation rod. Previous guidelines established for selective fusion with conventional posterior instrumentation (Harrington or Luque rods) may not be applicable to derotation with Cotrel-Dubousset instrumentation.

Adolescent↗

PubMed1991

The clinical application of neurogenic motor evoked potentials to monitor spinal cord function during surgery.

The purpose of this study was to report results from 300 cases (177 children, 123 adults) administered somatosensory and neurogenic motor evoked potentials during surgery. Of these 300 cases, there were 16 cases of spinal fractures, 16 neurosurgical cases, 28 vascular cases, and 240 cases of elective posterior spinal deformity requiring instrumentation. Results indicated that somatosensory evoked potentials, especially cortical components, demonstrated greater variability than neurogenic motor evoked potentials. Variability was attributed to anesthesia and unknown factors. Neurogenic motor evoked potentials proved to be a more valid indicator of postoperative motor status than somatosensory evoked potentials. Based on their anatomic substrates and results from this study, it was recommended that somatosensory evoked potentials and neurogenic motor evoked potentials be used to monitor spinal cord function during surgery that would place that structure at risk.

Adolescent↗

PubMed1991

Treatment of metastatic prostate cancer of the spine.

There is a wide spectrum of presentations for prostate cancer metastatic to the spine. Important factors are the patient's age and general health; the extent and location of spinal involvement; the patient's neurologic status and degree of pain; the relative contribution of a blastic or lytic response; and the experience and training of the spinal surgeon, medical oncologist, and radiation oncologist. The spine is both a weight-bearing structure and a housing for the spinal cord, and failure to consider both functions may lead to unsatisfactory treatment results. Treatment options include hormonal therapy, inhibitors of bone metabolism, glucocorticoid therapy, radiotherapy, halo-vest, surgical debridement, decompression and stabilization, and appropriate pain management and support. One must not lose sight of the fact that the goals are palliation and that ultimate demise is unavoidable in patients with metastatic prostate cancer.

Humans↗

PubMed1990

Surgical treatment of hematogenous vertebral Aspergillus osteomyelitis.

Three cases of Aspergillus fumigatas vertebral osteomyelitis failed courses of medical treatment. Each was subsequently treated with anterior vertebral debridement and posterior segmental spinal instrumentation. Despite poor nutritional and immune systems, resolution of the infection and subsequent anterior ankylosis occurred in each patient, with follow-up ranging from 1 to 3 years. If patients with aspergillus vertebral osteomyelitis do not respond to medical treatment, early surgical debridement and stabilization in combination with intravenous amphotericin B can lead to resolution and bony ankylosis.

Adult↗

PubMed1990

Relationship between duration of spinal cord ischemia and postoperative neurologic deficits in animals.

Twenty hogs were administered the following procedures before, during, and after overdistraction of the spinal column at T5-T6: somatosensory (SEP) and neurogenic-motor evoked potentials (NMEPs), hydrogen clearance procedures, Stagnara wake-up tests, and aortic-injection of silastic plastic. To ensure that overdistraction was possible, a nonosseous, circumferential osteotomy was made at T5-T6 and distraction applied in one-ratchet increments using Harrington instrumentation. Overdistraction was maintained for 3, 5, 6, 10, 15, 20, 25, or 30 minutes. Results indicated that the duration of overdistraction, as represented by lost NMEPs, was always correlated with the animal's clinical status on wake-up test. If overdistraction was maintained more than 6 minutes, 100% of the animals demonstrated positive wake-up results; if maintained between 5 and 6 minutes, 75% demonstrated positive wake-up results; and if maintained less than 5 minutes, only 25% demonstrated positive wake-up results. Time-to-loss of the NMEPs and SEPs, after onset of overdistraction, fell within two groups: slow and fast. In the slow group, it required slightly more than 20 minutes (mean = 20.6) for the potentials to be lost, while in the fast-loss group data were lost in slightly less than 4 minutes (mean = 3.6). Blood flow studies and inspection of the spinal cord revealed that the mechanism of action for the slow group appeared to be ischemia of the spinal cord that extended several centimeters above and below the site of maximum distraction. In the fast-loss group, it appeared that gross structural damage, with some very localized ischemia, were the mechanisms of actions influencing the integrity of the spinal cord.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Sagittal plane analysis in idiopathic scoliosis patients treated with Cotrel-Dubousset instrumentation.

One hundred sixty patients with idiopathic scoliosis treated with Cotrel-Dubousset instrumentation (CDI) underwent preoperative and postoperative sagittal plane analysis of the thoracic spine, thoracolumbar junction, and lumbar spine. The data suggest that mild to moderate improvements in thoracic hypokyphosis are possible. When crossing the thoracolumbar junction, reversal of rod bend and reversal of hooks on the derotation rod appear to provide the most physiologic sagittal contour. Cotrel-Dubousset instrumentation to the mid and distal lumbar spine can preserve and, at times, enhance lumbar lordosis.

Humans↗

PubMed1990

Relationship between duration of spinal cord ischemia and postoperative neurologic deficits in animals.

Stagnara wake-up tests, blood flow measures, somatosensory evoked potentials (SEPs), and neurogenic-motor evoked potentials (NMEPs) were elicited from 20 hogs before and after spinal cord overdistraction at L3-L4. Overdistraction was maintained from 5 to 30 minutes after loss of NMEPs. Results suggest that the longer the duration of overdistraction the greater the likelihood of paraplegia. Blood flow measures indicated that reduced perfusion was greatest at the distraction site but extended proximally and distally. Finally, NMEPs were more sensitive to onset of overdistraction and a more valid indicator of paraplegia than SEPs. NMEPs should provide the surgeon with more time for initiation of intervention techniques than SEPs. Because NMEPs and SEPs provide information regarding different spinal cord tracts, the authors continue to use both methods for monitoring the functional integrity of the human spinal cord during corrective spine surgery.

Animals↗

PubMed1990

Relationship among level of distraction, evoked potentials, spinal cord ischemia and integrity, and clinical status in animals.

Somatosensory evoked potentials (SEPs) and neurogenic-motor evoked potentials (NMEPs) were recorded after overdistraction of the spinal cord at T5-T6, T12-L1, or L3-L4. Measures of spinal cord perfusion and clinical status were also administered. Results indicated that stiffer spinal segments allowed less distraction than more flexible segments. SEPs and NMEPs were lost quickly after overdistraction in stiff segments and slowly in more flexible segments. However, SEPs were less sensitive than NMEPs to effects from overdistraction. Spinal cord perfusion and integrity were consistent with reduced perfusion and structural damage after overdistraction in stiff segments; extremely reduced perfusion but no structural changes in more flexible segments. The application of these results to the clinical situation was provided.

Animals↗

PubMed1990

Sagittal plane analysis in idiopathic scoliosis patients treated with Cotrel-Dubousset instrumentation.

One hundred sixty patients with idiopathic scoliosis underwent preoperative and postoperative sagittal plane analysis of the thoracic spine, thoracolumbar junction, and lumbar spine. The data suggest that mild to moderate improvements in thoracic hypokyphosis are possible. When crossing the thoracolumbar junction, reversal of rod bend and reversal of hooks on the derotation rod appears to provide the most physiologic sagittal contour. Cotrel-Dubousset instrumentation to the mid and distal lumbar spine can preserve and, at times, enhance lumbar lordosis.

Adolescent↗

PubMed1990

Blood flow direction in the lumbar nerve root.

The effect of clipping on lumbar nerve root blood flow rates in the region of the nerve root canal was studied experimentally in the hog. Blood flow rate was measured using the hydrogen washout technique. When the entrance zone was clipped with a microvascular clip, blood flow rate of the nerve root was decreased by 37% in comparison with the initial control rate; clipping at the exit zone reduced blood flow rate by 69%. Blood flow direction in the lumbar nerve root within the nerve root canal was found to be predominantly proximal. The current data indicate that the more lateral the impingement of the nerve root occurs, the more ischemic changes are induced.

Animals↗

PubMed1990

"Silent" spinal dislocation in a Charcot spine occurring postlaminectomy: case report and review of literature.

A 45-year-old man with transverse myelitis developed an unstable neuropathic spinal arthropathy manifesting as a "silent" L1-L2 dislocation after laminectomy and rhizotomies performed for increased spasticity. Treatment consisted of reduction, posterolateral spinal fusion with Cotrel-Dubousset instrumentation utilizing hooks and pedicular screws, and a posterior lumbar interbody fusion. The authors conclude that laminectomy on a chronic paralytic through the insensate area should be coupled with fusion and instrumentation even if the facet joints and capsules are preserved during the laminectomy.

Adult↗

PubMed1990

Chylothorax after posterior spinal instrumentation and fusion.

Chylothorax occurred in a 16-year-old girl after posterior spinal fusion and instrumentation for idiopathic scoliosis. Nonoperative management, including chest tube drainage for 26 days and total parenteral nutrition, successfully treated this unusual complication after a posterior spinal fusion.

Adolescent↗