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Biomedical subjects

H M Mayer

Publications and source records attributed to H M Mayer.

At least 37 records · Page 2Linked to original sources
PubMed1995

Telemeterized load measurement using instrumented spinal internal fixators in a patient with degenerative instability.

STUDY DESIGN: In the present study, the loads in an internal spinal fixation device were measured in vivo. OBJECTIVES: To determine the implant loads for different activities before and after additional anterior stabilization of the spine. SUMMARY OF BACKGROUND DATA: Mathematical models exist for predicting spinal loads. The intradiscal pressure has been measured for many body positions and activities. The loads on internal spinal fixation devices have not been measured before in vivo. METHODS: Telemeterized AO spinal internal fixators were implanted in a patient with degenerative instability. The implants allow the in vivo measurement of three force components and three moments acting in the implant. RESULTS: When the patient was lying in relaxed positions, the implant loads were small. Before additional anterior stabilization, the loads were also small for sitting, standing, and walking. The bending moment in the sagittal plane was less than 3 Nm for these activities. The highest loads within the first 4 weeks after implantation were measured while the patient turned from a supine to a lateral position against the advice of the physiotherapist. After anterior stabilization, the maximum loads for the relaxed lying positions were altered only slightly. Much higher axial forces and bending moments were measured for sitting, standing, and walking. The maximum bending moment increased to 5-8 Nm for these activities. The implant loads for sitting were not higher than for standing. CONCLUSION: Flexion and lateral bending of the upper body and weight-carrying during sitting, standing, or walking should be avoided in the first few months after anterior stabilization.

Bone Screws↗
PubMed1995

The "mirror image" and "two-thirds" types of hemispherical spondylosclerosis.

Clinical and radiological examination of 167 hemispherical spondylosclerosis (HSS) patients (56 male, 111 female) revealed a total of 186 cases of HSS with multiple incidences occurring in 18 patients. Radiologically these HSS cases were characterized by erosion and new bone formation at the inferior and upper end plate of the vertebra below, periosteal bone apposition or ossification of the anterior longitudinal ligament, spondylophytes, and signs of degenerative alteration of the vertebra and disc. In addition, the size and location (anterior, middle, posterior third) of each HSS in the lateral view was investigated. The cases were also investigated for reflection phenomenon between supra- and infradiscal sclerosis and for kyphotic angulation of the two adjacent vertebrae. The results showed that in 105 cases (56.5%) the HSS filled out the entire vertebral area; 97 cases (52.2%) showed a mirror-image type HSS; while in 8 cases (4.3%), the infradiscal sclerosis was polymorphic. In 81 cases (43.5%), the sclerosis was limited to the anterior two-thirds; this is termed "two-thirds" type. All 81 of these cases of HSS showed a kyphotic angulation of at least 4 degrees. Of these, 61 (32.8% of the total) showed reflection phenomenon while 20 (10.7% of the total) had polymorphic infradiscal sclerosis. Overall, 158 cases of HSS (85%) exhibited the reflection phenomenon between supra- and infradiscal sclerosis, whereas 28 cases (15%) revealed polymorphic sclerosis of the subadjacent vertebra. Kyphotic angulation was completely absent when HSS was visible in the entire vertebra. A dorsal gap of the disc space was seen in 36 cases (19.4%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Exogenous lumbar spondylodiscitis following a stabwound injury and vertebral fracture. A case report and review of the literature.

Exogenous spondylodiscitis is a rare event and is usually iatrogenic. Non-iatrogenic exogenous spondylodiscitis has been described in the literature following transabdominal gunshot wounds associated with injury to the intestines and spine. Several cases of traumatic meningitis and one of a traumatic meningocele following an injury of the spinal sac have been reported. No report of exogenous spondylodiscitis complicating a stabwound has been published. This is a report of exogenous spondylodiscitis following a paravertebral stabwound with a knife in association with a superior wedge fracture of L2.

Adult↗
PubMed1995

[Spondylitis: borderline findings in magnetic resonance tomography].

MR studies of 41 patients with confirmed spondylitis were evaluated with regard to imaging findings resembling metastases or fracture. 30 patients had MR results considered typical for spondylitis (contiguous changes in two vertebrae and disc, soft tissue tumour). 11 patients had MR studies differing from this pattern. Absence of soft tissue involvement and discontinuous marrow changes may be misdiagnosed as bone marrow metastases.

Adult↗
PubMed1995

[Technique and economics of first worldwide roentgen conference via public phone lines with the Medical Desktop-Conference and Integrated Services Digital Network].

The introduction of the world's first Medical Desktop-Conference via public phone lines (ISDN-S2M) in spring 1994 for the weekly discussion of radiological findings with 25 orthopedic surgeons has proved the effectiveness of this system developed by the project BERMED. The use of standard hard- and software as well as ISDN are the most important factors to keep the system costs low. Technical advantages can be seen in the immediate, loss-free transmission of image and other patient-related data and in the integration of digital archives. Medical advantages are the 24-hour-availability of the radiologist and quality-control of the radiologists work. Practitioners and external hospitals can be tied closely to radiological service centers by using ISDNetwork.

Computer Communication Networks↗
PubMed1994

Spine update. Percutaneous lumbar disc surgery.

Various techniques of percutaneous lumbar disc surgery have become popular for treating lumbar disc herniations. There is a vast and increasing body of literature on this topic that consists mainly of retrospective, uncontrolled clinical studies, technical articles, and case reports. A literature analysis revealed two different techniques, both termed "percutaneous discectomy." One is the selective removal of nucleus pulposus from the herniation site with various manual and automated instruments under endoscopic control (percutaneous nucleotomy with discoscopy, arthroscopic microdiscectomy, percutaneous endoscopic discectomy); the other is the removal of nucleus pulposus from the center of the disc space with one single automated instrument (automated percutaneous lumbar discectomy) to achieve an intradiscal decompression. Selective percutaneous discectomy with endoscopic control requires a restrictive selection of patients and can achieve clinical results comparable with microdiscectomy under controlled conditions. There is no scientifically proven validity of automated percutaneous lumbar discectomy compared with standard surgical methods and chemonucleolysis. The majority of the articles analyzed did not fulfill the selection criteria of Spine. Additional prospective, randomized and controlled studies are needed to define the eventual role of percutaneous lumbar discectomy on a scientific basis.

Diskectomy, Percutaneous↗
PubMed1994

[MRT in degenerative diseases of the cervical spine].

MRI has grown increasingly important in recent years in diagnosis of degenerative disease of the cervical spine, due to improvements of method that have made it a valuable diagnostic tool. The following contribution gives a brief introduction to the pathophysiology of degenerative changes in the cervical vertebral column and to the indications for MRI, describing within the framework of imaging the present state of MR examination technique. The ranking of the various gradient echo sequences, of the 3D methods and of the administration of contrast media in cervical myelopathy and radiculopathy is discussed.

Cervical Vertebrae↗
PubMed1993

Percutaneous endoscopic lumbar discectomy (PELD).

Percutaneous endoscopic lumbar discectomy (PELD) is a new technique for the decompression of the lumbar disc space and removal of nucleus pulposus via a posterolateral approach. The technique was introduced in Germany by the authors in April 1987. The method is indicated in patients with nonsequestrated lumbar disc herniation with an intact dorsal longitudinal ligament. In local anesthesia, a working cannula (OD 5 mm) is placed at the dorsal lateral border of the disc. The disc space is opened with anulus trephines and the nucleus pulposus is removed with rigid and flexible forceps as well as with automated shaver systems under intermittent endoscopic control (discoscopy). The procedure is performed in local anesthesia. The results of the first thirty patients with a follow-up time between 6 months and 17 months could be graded as excellent in 13 cases, as good in 9 cases, as fair in 6 cases, and as bad in 2 cases. The relief of symptoms as judged by the patients was between 70-100 percent in the majority of the cases. Three patients had to be reoperated at the same level and site, because of either persistent or recurrent sciatica. The performance in local anesthesia, the atraumatic extraspinal approach, the reduced time of hospitalization and postoperative morbidity as well as the reduced time of work incapability are the main advantages of this new method.

Adult↗
PubMed1993

Nucleus pulposus regeneration after chemonucleolysis with chymopapain?

Chemonucleolysis was unsuccessful in 100 out of 519 patients with herniated lumbar discs treated within a period of 3 years. These patients were subsequently submitted to open surgery. Disc material from 88 of the 100 patients was examined by light microscopy (hematoxylin and eosin, van Gieson's, Nissl's and periodic acid-Schiff staining) to verify the effect of enzymatic activity compared to the histologic findings in a similar control group. In 84 of the 88 cases, signs of enzymatic activity were revealed by eosinophilia of the ground substance, altered Nissl staining and positive periodic acid-Schiff reaction within the chondrocyte halos. These alterations indicate that the enzyme was active and confirm the results of previous studies with smaller numbers of cases. Histologic alterations were quantified according to the intensity and extent of staining. The signs of enzymatic activity were significantly (P < 0.01) stronger after short time intervals between chemonucleolysis and surgery than after long intervals. These findings may be interpreted as indicating a regenerative potential of the nucleus pulposus.

Adult↗
PubMed1993

Percutaneous endoscopic discectomy: surgical technique and preliminary results compared to microsurgical discectomy.

Percutaneous endoscopic discectomy is a new technique for removing "contained" lumbar disc herniations (those in which the outer border of the anulus fibrosus is intact) and small "noncontained" lumbar disc herniations (those at the level of the disc space and occupying less than one-third of the sagittal diameter of the spinal canal) through a posterolateral approach with the aid of specially developed instruments. The technique combines rigid straight, angled, and flexible forceps with automated high-power suction shaver and cutter systems. Access can thus be gained to the dorsal parts of the intervertebral space where the disc herniation is located. Percutaneous endoscopic discectomy is monitored using an endoscope angled to 70 degrees coupled with a television and video unit and is performed with the patient under local anesthesia and an anesthesiologist available if needed. Its indication is restricted to discogenic root compression with a minor neurological deficit. Two groups of patients with contained or small noncontained disc herniations were treated by either percutaneous endoscopic discectomy (20 cases) or microdiscectomy (20 cases). Both groups were investigated in a prospective randomized study in order to compare the efficacy of the two methods. The disc herniations were located at L2-3 (one patient), L3-4 (two patients), or L4-5 (37 patients). There were no significant differences between the two groups concerning age and sex distribution, preoperative evolution of complaints, prior conservative therapy, patient's occupation, preoperative disability, and clinical symptomatology. Two years after percutaneous endoscopic discectomy, sciatica had disappeared in 80% (16 of 20 patients), low-back pain in 47% (nine of 19 patients), sensory deficits in 92.3% (12 of 13 patients), and motor deficits in the one patient affected. Two years after microdiscectomy, sciatica had disappeared in 65% (13 of 20 patients), low-back pain in 25% (five of 20 patients), sensory deficits in 68.8% (11 of 16 patients), and motor deficits in all patients so affected. Only 72.2% of the patients in the microdiscectomy group had returned to their previous occupation versus 95% in the percutaneous endoscopic discectomy group. Percutaneous endoscopic discectomy appears to offer an alternative to microdiscectomy for patients with "contained" and small subligamentous lumbar disc herniations.

Adolescent↗
PubMed1992

Percutaneous endoscopic laser discectomy (PELD). A new surgical technique for non-sequestrated lumbar discs.

Basic features and techniques of percutaneous endoscopic laser discectomy are described and the results in 6 patients reported. Indications are: discogenic radicular symptoms, caused by disc protrusions, which do not respond to conservative treatment. Contra-indications are: major neurological deficit, segmental instability and spondylolisthesis, extruded disc prolapse, narrow spinal canal or lateral recess.

Adult↗
PubMed1992

The form and structure of the extruded disc.

There are no detailed data in literature concerning the histologic nature of the sequestered (extruded) lumbar disc, and on the frequency with which an extruded fragment, a prolapse or a protrusion are found at surgery. A prospective analysis of 100 consecutive cases of sequestered lumbar disc herniation submitted to surgical treatment revealed this group to represent 28.6% of all cases operated on for lumbar disc herniation. Patients (both male and female) with sequestered lumbar discs are significantly older than those with prolapsed (P < 0.01) and protruded (P < 0.001) discs. Single extruded fragments (n = 68) were twice as frequent as multiple ones (n = 32). The general belief that a 'sequestered (extruded) disc' is almost invariably composed of nucleus pulposus is not substantiated by this study: In 54 cases the extruded fragment consisted predominantly of nucleus material, whereas in 44 cases it consisted mainly of end-plate material. Multiple as well as recurrent sequestered fragments almost always consist of end-plate material. These findings may reflect the result of metabolic alterations in the course of disc degeneration.

Adult↗
PubMed1991

The results of "lumbar disc surgery" following unsuccessful chemonucleolysis.

A group of 100 patients submitted to microsurgical treatment for herniated lumbar disc following unsuccessful chemonucleolysis with chymopapain were retrospectively compared to a statistically comparable group of patients primarily submitted to microsurgery. This comparison demonstrated that previous unsuccessful chemonucleolysis has no influence on either the short-term or the long-term results of subsequent microsurgery.

Adult↗
PubMed1990

A case of dyschondroplasia associated with brain stem glioma: diagnosis by stereotactic biopsy.

We present a 24-year-old patient with multiple chondromas of both hands, the pelvis, the left leg, and an associated brain stem glioma. There was no evidence of hemangioma or dyschromia, and the condition was diagnosed as Ollier's disease, a special type of dyschondroplasia like Maffucci's syndrome and Kast's disease. An increased overall risk for development of malignant skeletal and nonskeletal tumors is associated with Maffucci's syndrome. The risk of malignant degeneration is lower in Ollier's disease. A glioma in the pons and the right lobe of the cerebellum was found in this patient. The literature describes an association with gliomas in only 12 cases of dyschondroplasia and an infratentorial localization in just one case. Signs of malignancy were histologically confirmed in 7 cases without significant preponderance of any one type. Our patient had a low-grade brain stem astrocytoma with fibrillar and gemistocytic components. A stereotactic serial biopsy made it possible to rule out malignant degeneration. Stereotactic brain tumor biopsy as a routine neurosurgical procedure is particularly valuable for deep space-occupying processes and forms the basis for therapy. In the present case, irradiation was not recommended.

Adult↗
PubMed1989

[Differential therapy of lumbar intervertebral disk protrusion].

Surgical treatment for protrusion of intervertebral disks in the lumbar region has been considerably optimised. Progress in imaging techniques has enabled representation and recording of intervertebral disk disorders at various pathogenetic stages. Backache has become endemic in industrial countries, in the course of time, and is often accompanied by pseudoradicular ischialgia. It is quite often uncritically attributed to intervertebral disk damage on the basis of findings recorded from computed tomography. With patients increasingly suffering pain, this has in many cases led to rash surgical decisions. -Principles of differential diagnosis by which the complexity of morphological findings underlying clinical symptoms is taken into due consideration are absolutely necessary to counter the above developments. Indications for neurosurgical differential therapy for protrusion of intervertebral disks at lumbar level should be individually established with due consideration of therapeutic procedures available and of the severity of complaints. The percutaneous and microsurgical techniques described in this paper are likely to suggest that procedures, such as hemilaminectomy and laminectomy are no longer justified unless exceptional cases are to be handled.

Humans↗
PubMed1988

Percutaneous diskectomy in the treatment of pediatric lumbar disk disease.

Intervertebral lumbar disk herniation in children and adolescents is rare. The incidence varies between 0.8% and 3.8% of all disks treated surgically. The uncertainty concerning operative or conservative treatment of this rare clinical entity has led to considering the use of atraumatic techniques, such as chemonucleolysis or percutaneous diskectomy. We report the unusual case of an 11-year-old girl with herniated disk at the L4-5 level treated by percutaneous diskectomy. This is, to our knowledge, the first case of a child treated by this technique. The technical simplicity, the minimal trauma it causes, and the excellent clinical result show that percutaneous diskectomy is a reasonable therapeutic alternative in the treatment of juvenile disks.

Child↗