Electrical stimulation of the central gray for pain relief in human: autopsy data

Post-mortem histopathology of a pediatric brain after bilateral DBS of GPI for status dystonicus: case report and review of the literature

PURPOSE

To investigate the effects of deep brain stimulation (DBS) electrodes on the brain of a dystonic pediatric patient submitted to bilateral DBS of the globus pallidus internus (GPI).

METHODS

An 8-year-old male patient underwent bilateral DBS of GPI for status dystonicus. He died 2 months later due to multiorgan failure triggered by bacterial pneumonia. A post-mortem pathological study of the brain was done.

RESULTS

At visual inspection, no grossly apparent softening, hemorrhage, or necrosis of the brain adjacent to the DBS lead tracts was detected. High-power microscopic examination of the tissue surrounding the electrode trajectories showed lymphocyte infiltration, astrocytic gliosis, microglia, macrophages, and clusters of multinucleate giant cells. Significant astrocytosis was confirmed by GFAP staining in the electrode site. The T cell lymphocyte activity was overexpressed with activated macrophages detected with CD3, CD20, CD45, and CD68 stains respectively. There was no gliosis or leukocyte infiltration away from the surgical tracks of the electrodes.

CONCLUSION

This is the first post-mortem examination of a child's brain after bilateral DBS of GPI. The comparison with adult post-mortem reports showed no significant differences and confirms the safety of DBS implantation in the pediatric population too.

Brain alterations with deep brain stimulation: New insight from a neuropathological case series

BACKGROUND

Previous studies on human brain tissue alterations caused by deep brain stimulation described glial and reactive inflammatory changes. In the current pathoanatomical study, we extended the analysis to signs of axonal changes and the influence of concomitant disease.

METHODS

Brains of 10 patients with Parkinson's disease or essential tremor and a total of 18 electrodes were systematically examined up to 7.5 y after surgery.

RESULTS

In general, tissue that had long-term contact with the electrode material exhibited astrogliosis in all, T-lymphocytes in 93%, and multinucleated giant cells in 68% of patients. Immunohistochemistry showed an increase in amyloid precursor protein immunoreactive axonal swellings in the brain at the electrically active parts of the electrodes. Patients who died of septicemia showed a more severe astrogliosis and giant cell reaction than patients who died of cardiovascular events. Parkinson's disease or essential tremor did not differentially produce histopathological changes around the electrodes.

CONCLUSION

Long-term electrical stimulation by deep brain stimulation causes minor axonal changes. The cause of death, but not the underlying neurological disease, affects the histopathological changes around the electrode. The findings need to be reproduced by examining larger patient subgroups.

Histological alterations induced by electrode implantation and electrical stimulation in the human brain: a review

Objectives.  Electrical brain stimulation is used as a treatment for patients with intractable chronic pain and movement disorders. However, the implantation of electrodes and electrical stimulation may induce histological changes around the electrode tip. We aimed to review the histological changes in humans that were electrically stimulated in the brain. Methods.  We traced 26 autopsy studies of which 19 patients received cerebellar stimulation and 37 patients deep brain stimulation. Results.  Electrode implantation and electrical stimulation induced in part of the cases formation of a fibrous sheath around the electrode, loss of fairly large neurons, and limited gliosis. Macroscopic lesions were present in only some cases, mostly due to pulling at the extension cable in the postoperative evaluation period preceding definite implantation of the electrode wire and stimulator. Conclusions.  Electrical brain stimulation induces histological changes in some patients. According to electrical brain stimulation studies in animals, these changes can be related to the charge and charge density per phase (and their interaction).

Long-term deep brain stimulation in a patient with essential tremor: clinical response and postmortem correlation with stimulator termination sites in ventral thalamus. Case report

Essential tremor can be suppressed with chronic, bilateral deep brain stimulation (DBS) of the ventralis intermedius nucleus (Vim), the cerebellar receiving area of the motor thalamus. The goal in this study was to correlate the location of the electrodes with the clinical efficacy of DBS in a patient with essential tremor. The authors report on a woman with essential tremor in whom chronic bilateral DBS directed to the ventral thalamus produced adequate tremor suppression until her death from unrelated causes 16 months after placement of the electrodes. Neuropathological postmortem studies of the brain in this patient demonstrated that both stimulators terminated in the Vim region of the thalamus, and that chronic DBS elicited minor reactive changes confined to the immediate vicinity of the electrode tracks. Although the authors could not identify neuropathological abnormalities specific to essential tremor, they believe that suppression of essential tremor by chronic DBS correlates with bilateral termination of the stimulators in the Vim region of the thalamus.

Deep brain stimulation: a review of basic research and clinical studies

Deep brain stimulation for pain control in humans was first used almost 30 years ago and has continued to receive considerable attention. Despite the large number of clinical reports describing pain relief, numerous studies have indicated that the results of these procedures vary considerably. In addition, many neurosurgeons find the procedures unpredictable, and considerable disagreement still exists regarding important issues related to the technique itself. This review gives an historical overview of the relevant basic and clinical literature and provides a critical examination of the clinical efficacy, choice of stimulation sites, parameters of stimulation, and effects on experimental pain. Finally, we give suggestions for future research that could more definitively determine the usefulness of deep brain stimulation for pain control.

Deep brain stimulation in the treatment of chronic pain in man: where and why?

In current clinical practice, two brain structures are stimulated for the relief of chronic pain, namely the somatosensory thalamic nuclei (VPL-VPM) and the periventricular and periaqueductal gray matter (PVG-PAG). Whereas stimulation of the VPL-VPM is almost exclusively used for the treatment of deafferentation pain, stimulation of the PVG-PAG is mostly used in cases of nociceptive pain. We present our results of VPL-VPM stimulation in 36 patients with deafferentation pain. Initial pain relief was obtained in 61% of patients. To-day, after a mean follow-up of more than 4 years, 30% are still pain free. This success rate was found to be lower than the mean reported success rate of 57%, based on a survey of the world literature. Upon reviewing the literature, it was apparent that the reported success rates vary considerably between different authors. Some tentative explanations are given for this large discrepancy in success rate. The mechanisms by which electrical stimulation of the VPL-VPM suppresses deafferentation pain remain to be elucidated. Recent clinical and experimental findings suggest that a dopaminergic mechanism might be involved.

Stimulation of the nucleus paraventricularis thalami suppresses scratching and biting behaviour of arthritic rats and exerts a powerful effect on tests for acute pain

In 20 arthritis-sensitive Wistar rats, an electrode was implanted in the paraventricular thalamic nucleus (PV). In the tail-flick and hot-plate test, PV was stimulated continuously for a period of 30 min, during which every 5 min either a tail-flick or hot-plate test was performed. Stimulation of PV induced important prolongations of the reaction times on tail-flick and hot-plate tests. However, there was no significant correlation between the results of the two tests. The effect of stimulation was immediate and did not outlast the stimulation period. PV stimulation did not give rise to tolerance, either within the stimulation period of 30 min, or during the successive testing days. After the termination of these acute pain tests, rats were inoculated with Mycobacterium butyricum. All animals developed polyarthritis. PV stimulation had a profound suppressive effect on the scratching and biting behaviour displayed by the animals. This reduction in scratching and biting behaviour was specific for PV stimulation since stimulation of another target, the ventrolateral thalamic nucleus (4 animals), had no effect on these behaviours. The attenuation of the scratching and biting behaviour was not a result of a general motor impairment, since other behaviours increased (running and sniffing) or did not change. There was no significant correlation between the results of scratching behaviour with those of the tail-flick and hot-plate test.

Subcortical electrical stimulation for control of intractable pain in humans. Report of 122 cases (1970-1984)

Chronic electrical stimulation of the subcortical area of the brain by implanted electrodes provides satisfactory control of a number of intractable pain syndromes that are refractory to medication. This series of 122 patients who underwent electrode implantation for the control of severe chronic pain was evaluated over a follow-up period of 2 to 14 years. Of the 65 patients with pain of peripheral origin, who were treated with stimulation of the periaqueductal gray region (PAG), 50 obtained successful pain control. Of 76 patients with a deafferentation pain syndrome, 44 obtained control of the dysesthesia with stimulation of the subcortical somatosensory region. Nineteen patients with both leg and back pain received electrodes in the PAG and the somatosensory regions; whereas back pain was relieved by PAG stimulation, dysesthetic leg pain was controlled more effectively by somatosensory region stimulation. The electrical stimulation technique appears to provide long-term pain control safely, with few side effects or complications.

[The effect of the central gray matter in cats on pain during electric stimulation of the aqueduct]

In 54 cats electrical stimulation of the periaqueductal grey matter was performed by electrodes which were placed in distinct regions of the aqueduct. The influence on pain was studied by the formalin test. Motor behaviour was observed. The results show an obvious inhibition of pain reactions, which was most effective in the upper of the aqueduct. The motor functions were disturbed only in some cats with lesions of the cerebellar vermis. The advantage of this method is that it is not necessary to place the stimulating electrode into the midbrain tissue. This procedure might be appropriate for patients with severe chronic pain in face and body, in whom other surgical methods have failed.

A correlative anatomical and clinical study of pain suppression by deep brain stimulation

The clinical results of electrical stimulation in medial thalamic regions for cancer pain have been correlated with the exact location of the stimulation sites. Five brains were examined by post-mortem histology. Chronic implantation of enamel coated platinum-iridium electrodes for up to 17 months caused relatively mild glial and neuronal reactions and no significant haemorrhage or infarction. The anatomical verifications showed that the electrodes were close to, but not exactly in, the regions defined by the stereotactic coordinates. From the clinico-anatomical correlations it appears that good pain relief can be obtained by electrical stimulation in the periventricular gray region of the posterior thalamus.