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D Jeanmonod

Publications and source records attributed to D Jeanmonod.

30 records · Page 2Linked to original sources
PubMed1990

Ablative neurosurgical procedures for the treatment of chronic pain.

This article is devoted to ablative neurosurgical procedures used for the treatment of chronic pain. The authors detail only those procedures that are currently performed. The procedures are classified as those directed to the peripheral nerves, spinal roots and cranial nerves; the dorsal root entry zone; the ascending extra-lemniscal pathways. The authors have analyzed the results of their own series and those published in the literature. They concentrate on the rationale and neurophysiological effects of the operations.

Chronic Disease↗
PubMed1990

Intraoperative electrophysiological recordings during microsurgical DREZ-tomies in man.

Spinal cord surface evoked potentials were studied during surgery in 20 patients operated upon for pain and spasticity using microsurgical DREZ-tomy (MDT). The goal was to collect data on spinal cord physiology and analyze the effects of MDT. Thanks to a simplified floating tungsten microelectrode, intraoperative unit recordings were obtained from the dorsal horn of 3 spastic and 2 neurogenic pain patients.

Afferent Pathways↗
PubMed1990

Microsurgical ablative procedures in the peripheral nerves and dorsal root entry zone for relief of focal spasticity in the limbs.

When spasticity is harmful and localized in the limb(s), ablative procedures in the peripheral nerves or the dorsal root entry zone (DREZ) can be useful. The authors report on the long-term results of (1) selective tibial neurotomy in a series of 62 spastic feet, and (2) microsurgical DREZ-tomy in a series of 69 patients affected with hyperspasticity in the entire upper or lower limb(s).

Follow-Up Studies↗
PubMed1989

Intra-operative spinal cord evoked potentials during cervical and lumbo-sacral microsurgical DREZ-tomy (MDT) for chronic pain and spasticity (preliminary data).

We have undertaken the intra-operative study of spinal cord surface evoked potentials in patients operated upon for pain and/or spasticity using the microsurgical DREZ-tomy (MDT) procedure. The goals of this work were 1) to collect data on spinal cord evoked potential components and 2) to analyze the effects of MDT on spinal cord physiology. The MDT consists of a therapeutic lesion in the ventro-lateral aspect of the dorsal root entry zone, directed to the activatory circuitry, and aiming at returning the dorsal horn physiology towards inhibition. Averaged evoked potentials to peripheral nerve electrical stimulations were obtained from various loci on the surface of the dorsal columns of the cervical and lumbo-sacral spinal cord in 19 patients, using a small uninsulated silver ball electrode. An initial far-field positivity was found, corresponding to a compound action potential in the proximal part of the brachial (or lumbo-sacral) plexus. Pre-synaptic compound action potentials were identified, most often composed of multiple successive sharp peaks. A post-synaptic field potential generated in the dorsal horn was recognized. The MDT caused an immediate and irreversible decrease of amplitude down to a disappearance of the dorsal horn potential. This decrement was proportional to the amount of operated cord segments. In contrast, there has been a relative post-MDT sparing of the pre-synaptic action potentials originating from the operated cord segments, and the scalp contralateral parietal N 20 has been only reversibly affected by the therapeutic lesion. We thus argue for a specific involvement of dorsal horn physiology by the MDT, with a relative sparing of the dorsal column system.

Electric Stimulation↗
PubMed1989

Intra-operative unit recordings in the human dorsal horn with a simplified floating microelectrode.

The authors report on the development, for studies in man, of a tungsten, glass-coated, light and simple microelectrode, that is implanted by hand in open operative conditions under the microscope and floats freely with the moving target tissue. This technique has provided limited but nevertheless satisfactory unit activity isolations. Intra-operative unit recordings were obtained from the dorsal horns of 2 spastic and 2 neurogenic pain patients. In the latter, dorsal horn deafferentation hyperactivities after a peripheral and a centro-peripheral lesion were recorded, characterized by a continuous, spontaneous and unalterable high frequency hyperactivity.

Electrodes, Implanted↗
PubMed1989

Microsurgical DREZ-otomy for the treatment of spasticity and pain in the lower limbs.

The authors report on a series of 53 bedridden patients suffering from harmful spasticity in one (6) or both (47) lower limbs, who were treated with microsurgical DREZ-otomy. Surgery was performed to treat fixed abnormal postures in flexion in 49 patients and hyperextension in 3, and, additionally, to treat pain in 37 patients. Microsurgical DREZ-otomy was introduced in 1972, on the basis of anatomical studies of the human dorsal root entry zone (DREZ) showing a topographical segregation of the afferent fibers according to their size and functional destinations. It consists of a 2 mm deep microsurgical lesion directed at a 45 degrees angle in the posterolateral sulcus and penetrating the dorsal root entry zone in its ventrolateral aspect, at the level of all the rootlets considered involved in spasticity (and pain). It destroys mainly the lateral (nociceptive) and central (myotatic) afferent fibers as well as the facilitatory medial part of the Lissauer tract, while sparing most of the medial (lemniscal) fibers, the suppressor lateral part of the Lissauer tract, and more or less of the dorsal horn (DH). The postoperative results were evaluated after a mean follow-up period of 3 years and 4 months. Both spasticity and spasms were significantly decreased or suppressed in 75% and 88.2% of the patients, respectively. When present, pain was relieved without abolition of sensation in 91.6%. These benefits--combined with complementary orthopedic surgery in 23 patients--resulted in either disappearance or marked reduction of the abnormal postures in 85.3% of the patients and of articular limitations in 96.8%. Mild-to-severe complications occurred in 25 patients and precipitated or were responsible for death in 5. This is explained by the fact that the general and neurological conditions of most of the patients--especially those affected by multiple sclerosis--were precarious. MDT has, however, enabled a majority of these severely disabled patients to sit and lie comfortably, and has allowed them to reach a significantly improved quality of life.

Adolescent↗
PubMed1989

Application of CT-directed stereotaxy in the determination of functional neurosurgical targets in the diencephalon and cerebral hemisphere.

The descriptions of two techniques allowing for CT target determination in functional neurosurgery are presented, the first for thalamic and peri-thalamic explorations in the treatment of dyskinesiae and chronic pain, the second for the implantation of multiple hemispheric depth electrodes in the assessment of chronic drug-resistant epilepsy.

Cerebral Ventricles↗
PubMed1984

A silver and gold technique for axons and axon-bundles in formalin-fixed central and peripheral nervous tissue.

We have modified the reduced silver procedure of Liesegang and added a gold treatment. The technique has been successfully and routinely used to impregnate both peripheral and central nervous tissues of mice of different ages, and central nervous tissue of man. It was applied on conventionally (formalin) fixed and cryostat-cut material. In the periphery, nerves, individual axons, and sensory and motor endings stained a dark purple. In the brain, both bundles of axons and individual fine axonal branches were stained. When counterstained by a Nissl method, an excellent overall image of CNS structure is obtained.

Age Factors↗
PubMedDate not supplied

Three transverse dipolar generators in the human cervical and lumbo-sacral dorsal horn: evidence from direct intraoperative recordings on the spinal cord surface.

In the context of the intraoperative study of spinal cord surface evoked potentials in patients operated upon for chronic pain and spasticity, we have undertaken an analysis of the dipolar dorso-ventral organization of surface spinal cord evoked potentials in man. Averaged evoked potentials to peripheral nerve electrical stimulations were obtained from the dorsal and ventral pial surface of the cervical and lumbo-sacral spinal cord (7 pairs from 5 patients), using a small silver ball macroelectrode, positioned during open neurosurgical approaches. We found that the dorsally recorded N13 and N24 waves reversed into ventral P13 and P24 waves respectively. A second negative potential, N2, and a late prolonged positivity, P, similarly reversed into a P2 and an N wave respectively. Our data add up to a collection of skin, oesophageal, epidural, pial and intramedullary recordings in man and animals to provide the evidence for a transverse dipolar organization of the human postsynaptic N13, N24 and N2 potentials, originating from deep layers of the cord dorsal horn, and for a similar organization of the P wave, which has been shown to correlate with presynaptic inhibition on primary afferent fibres.

Evoked Potentials, Somatosensory↗
PubMedDate not supplied

The human cervical and lumbo-sacral evoked electrospinogram. Data from intra-operative spinal cord surface recordings.

We have undertaken the analysis of the human 'evoked electrospinogram' during intra-dural surgical explorations in 20 patients. Averaged spinal cord surface evoked potentials to peripheral nerve electrical stimulation were obtained from various restricted loci on the pial surface of the cervical and lumbo-sacral spinal cord. The brachial plexus P9 potential and its lumbo-sacral counterpart P17 were recorded as ubiquitous initial far-field positivities. The pre-synaptic compound action potentials N11 and N21 dwelt on the ascending slope of N13 and N24 respectively. They were composed of 1-5 sharp peaks and collected from the dorsal and dorso-lateral positions mainly, on the cervical and lumbo-sacral cord respectively. They are thought to be generated in the proximal portion of the dorsal root, the dorsal funiculus and the afferent collaterals to the dorsal horn. Compound action potentials could also be gathered from the surface of the dorsal roots, the cervical N10 and lumbo-sacral N19 potentials. The large cervical N13 and lumbo-sacral N24 waves originate from a dorso-ventral post-synaptic dipole, generated in deep laminae of the dorsal horn during the activation of large diameter afferent fibers. These waves were maximal on the main entry cord segments of the stimulated nerves and fell off on the 1-4 more rostral and caudal segments. The N2 wave is the dorsal component of another post-synaptic dorso-ventral dipole generated in deep laminae of the dorsal horn but activated by medium diameter afferent fibers. The latest event was the N3 wave, also possibly part of a dorso-ventral post-synaptic dipole, and generated by cells in the dorsalmost and deep dorsal horn laminae during the activation of small diameter afferent fibers. The P wave was a prolonged positive deflection which carried the N2 and N3 waves. It is the manifestation of pre-synaptic inhibition on primary afferent fibers. A supra-segmental ascending spinal cord volley was also described, composed of a long succession of sharp and low voltage peaks.

Adult↗