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Biomedical subjects

H Leu

Publications and source records attributed to H Leu.

16 recordsLinked to original sources
PubMed1996

Quantitative determination of ablation in weight of lumbar intervertebral discs with holmium: YAG laser.

BACKGROUND AND OBJECTIVE: Since 1992, the Ho:YAG 2100 nm laser has been in regular use in percutaneous lumbar disc surgery through the uniportal approach. In vitro experiments were done to find out the exact amount of ablated tissue in weight per energy used with the present beam delivery system. STUDY DESIGN MATERIALS AND METHODS: Thirty dissected human lumbar discs were treated with the Ho:YAG laser with 12 x 10(6) W/cm2 of effective power density, under 20 ml/min of continuous irrigation. The ablation amount was determined through indirect comparison, using the water content of each disc as reference, which was predetermined individually by freeze drying. RESULTS: The ablation of nucleus pulposus is 32.293 mg/kJ in dry weight and 104.719 mg/kJ in physiologic weight. The ablation capacity in annulus fibrosus is 50% of that in nucleus pulposus. CONCLUSION: With 20 kJ of energy, the average amount of energy used in actual operations, the mean ablation of nucleus pulposus is 0.556 + or - 0.06 (n = 3) grams in dry weight, and 1.89667 + or - 0.162 (n = 3) g in physiologic weight.

Adult↗
PubMed1996

Hereditary sensory and autonomic neuropathy type I (Thévenard's disease).

Radiographic and MR findings of two cases of hereditary sensory and autonomic neuropathy type I are reported. This rare disease has a non-specific radiographic and MR appearance. Differential diagnosis includes other types of hereditary and acquired sensory neuropathies affecting small myelinated and unmyelinated nerve fibers, as well as vascular abnormalities and lesions of the spinal cord.

Adult↗
PubMed1992

[Endoscopy of the spine: minimally invasive therapy].

Since 1982 discoscopy has proved its value as a mean of continuous optic control of percutaneous intradiscal procedures. Thus, precisely oriented removal of disc tissue became possible for posterior decompression. Since 1989, discoscopy has opened the way for optically controlled intradiscal laser application. Besides decompressive procedures, since 1988 specific elaboration of the vertebral plates for percutaneous interbody fusion has also become available under discoscopic control. A most promising prospect is the technique of foraminoscopy introduced in 1991, which also opened the way to extradiscal exploration. The further development of versatile fine working scopes will be a bigger and bigger challenge to conventional techniques, as the concept of minimal intervention in spine surgery becomes more and more complete.

Endoscopes↗
PubMed1991

[Percutaneous nucleotomy with disk endoscopy--a minimally invasive therapy in non-sequestrated intervertebral disk hernia].

The conventional open surgical approach for the treatment of lumbar disc herniation, introduced over 50 years ago, is often followed by tenacious consecutive complaints due to segmental instability or epidural scarring: the so called post-laminotomy syndrome. Introduced since 1979, Percutaneous nucleotomy, for patients without free sequestration of disc tissue, forms a true alternative due to its minimal invasiveness. Via a dorsolateral approach, most sparing the dorsal musculo-ligamental apparatus, a precise decompression can be achieved without scar-prone irritation of the peridural space. Considering the precise range of indication, preoperative selection of patients deserves most attention. An analysis of the 174 patients operated by this technique in the first 10 years shows favourable outcome in over 85% of the controls.

Adolescent↗
PubMed1991

Percutaneous nucleotomy: technique with discoscopy.

In its first decade of use, percutaneous nucleotomy has proven its value in decompressive indications for lumbar disc disease. Indications include contained disc herniations as isolated pathology, or in combination with other lumbar pathology at risk for decompensation after open hemilaminotomy, eg, spondylolysis/olisthesis or former open operative procedures. The precise indications underline the need for conclusive preoperative screening, such as disco-scan and contrast-discomanometry. Overall results are 85% favorable. Percutaneous intervertebral fusion is also presented.

Adult↗
PubMed1990

[Percutaneous nucleotomy. 10 years' experience, modern concepts].

The article reviews the authors' ten-year experience with the technique of percutaneous nucleotomy in the treatment of lumbar disc herniation. During this period 174 operations were altogether performed in 148 patients by means of this technique. The existing experience shows that this technique has fully justified itself in the indicated cased. It can be applied for the protrusion and subligamentous extrusion of the disc. Subligamentous sequestrum represents relative indication. For the evaluation of the condition of the disc the authors use as a standard the technique of contrast discomanometry. This examination method they consider in the indication of percutaneous nucleotomy for "conditio sine qua non". Of vital importance for the final result of the operation is to evaluate also the stability of the segment operated on. In cases where this segment in unstable it is necessary to supplement percutaneous nucleotomy with intercorporal spondylodesis. The question of stability of spine in the disc herniation has not been fully solved, yet. The solution of this problem will be significant also for the solution of the so called failed back syndrome.

Adolescent↗
PubMed1989

Does percutaneous nucleotomy with discoscopy replace conventional discectomy? Eight years of experience and results in treatment of herniated lumbar disc.

Percutaneous nucleotomy was first described in 1975 by Hijikata in Japan. In 1979 the present authors adopted this method for the treatment of lumbar disc herniation and modified Hijikata's original instruments. Since 1982 additional intradiscal optical control has been included by means of an adapted arthroscopic kit for more accurate and effective removal of the nucleus pulposus under direct view. This procedure is called discoscopy. Between 1979 and late 1987, the method was applied to 109 patients with lumbar disc herniation. The indications included lumbar sciatica that (1) was resistant to conservative treatment and (2) in which myelography and/or examination by computed tomography proved a disc protrusion without dislocation in the spinal canal. The level most affected was L4-L5. Major operative complications encountered were one vascular lesion and two cases of secondary spondylodiscitis. Clinical results in patients with other additional causes of sciatica, such as spondylolisthesis or relapse of disc herniation, were nearly as favorable as in isolated first-time disc herniation. The overall success rate was 72.5% (79/109 patients).

Adult↗
PubMed1988

[Acro-osteolysis syndrome: is a synthesis in view?].

The clinical phenomena of "acroosteolysis" means progredient destruction starting at metatarsal bony structures on primarily neurodystrophic mechanisms. A long-term case report illustrates clinical features and actual possibilities and limits in treatment. The current conceptions since the classic descriptions are resumed by large overview of literature. Open questions in current genetic and structural hypothesis show the difficulties of any nosologic classification. Common features with other neurodegenerative syndromes are more and more evident.

Adult↗
PubMedDate not supplied

[Percutaneous nucleotomy in the current treatment concept of lumbar ischialgia].

As a minimal invasive alternative to open disc surgery percutaneous nucleotomy has remarkably development for the treatment of contained lumbar herniation. In our experience since 1979, today available percutaneous concepts have to be clearly individualized in their range of indication following their specific technical limits. So a direct correlation of operative results remain restricted on overlapping ranges of indications. Progress in the technical field, in correlation with discoscopy, introduced since 1982, brought percutaneous interbody fusion in 1988, alloplastic percutaneous implants are in development. This facts let us foresee a remarkable evolution of percutaneous spine surgery comparable to arthroscopic knee surgery in the near future.

Humans↗