Cerebral Responses to Warmth and Heat and Cold Pain Measured by Positron Emission Tomography

Phasic heat and tonic cold stimuli that have different temporal patterns, afferent fiber activations, and perceived pain characteristics produce a shared pattern of cerebral activation in addition to modality specific activations. These patterns are different from the cerebral representation of innocuous temperature sensation. Functional brain imaging techniques provide an opportunity to study somatosensory organization in conscious humans under physiologic conditions, despite certain limitations of imaging modalities.     

Cerebral Blood Flow Effects of Pain and Acupuncture: A Preliminary Single-Photon Emission Computed Tomography Imaging Study

BACKGROUND: The purpose of this study was to investigate the cerebral blood flow changes associated with the analgesic effect of acupuncture in patients with chronic pain. METHODS: Seven patients presenting with a chronic pain syndrome and 5 healthy controls were included. All single-photon emission computed tomography (SPECT) scans were acquired with a uniform protocol. The patient group was injected with the radioisotope hexamethyl propyleneamine oxime (HMPAO) while experiencing their usual level of pain. A baseline scan was acquired approximately 20 minutes after administration of the HMPAO. The patient then underwent acupuncture therapy with needles placed in points specifically selected to relieve pain. When the pain improved, as determined by a 10-digit score for pain assessment, the patient was reinjected with HMPAO and imaged 20 minutes later for the acupuncture scan. The reference group also had a baseline and acupuncture scan, although the acupuncture itself was performed using a standardized set of needle points. RESULTS: The reference group participants were found to have significant increases in the thalamic and prefrontal cortex activity on the acupuncture scan compared to the baseline. The baseline scans of the pain patients showed significant asymmetric uptake in the thalami compared to controls. This asymmetry reversed or normalized after the acupuncture therapy. Significant correlations were observed between the change of activity in the prefrontal cortex and ipsilateral sensorimotor area. CONCLUSION: The results from these cases show that HMPAO-SPECT is capable of detecting changes in cerebral blood flow associated with pain and that acupuncture analgesia is associated with changes in the activity of the frontal lobes, brain stem, and thalami.     

Neurosurgical Invasive Techniques for Cancer Pain: A Pain Specialist's View

Neurosurgical techniques for management of cancer pain can be divided into two categories: reconstructive and ablative. For patients with pain from spinal metastatic disease, the newer surgical methods of anterior decompression and stabilization provide reliable pain control while preventing serious neurologic progression. Minimally invasive techniques for vertebral stabilization, such as vertebroplasty, may also effectively relieve pain from spinal metastases associated with low morbidity. Traditionally, stereotactic and functional neurosurgical techniques have been used to produce selective lesions in neuroanatomic pathways that mediate pain. Improvements in pharmacologic therapy, including treatment with intraspinal opioids, have led to a marked reduction in the use of ablative stereotactic methods. Nevertheless, cordotomy and certain other selectively destructive procedures still have a role in the management of patients with unremitting cancer pain. Technological developments in methods of lesion production could lead to the increased use of these methods.     

Position Emission Tomography/Single‐Photon Emission Tomography Neuroimaging for Detection of Premotor Parkinson's Disease

Premotor Parkinson's disease (PD) refers to a prodromal stage of Parkinson's disease (PD) during which nonmotor clinical features may be present. Currently, it is difficult to make an early diagnosis for premotor PD. Molecular imaging with position emission tomography (PET) or single‐photon emission tomography (SPECT) offers a wide variety of tools for overcoming this difficulty. Indeed, molecular imaging techniques may play a crucial role in diagnosing, monitoring and evaluating the individuals with the risk for PD. For example, dopaminergic dysfunctions can be identified by detecting the expression of vesicular monoamine transporter (VMAT2) and aromatic amino acid decarboxylase (AADC) to evaluate the conditions of dopaminergic terminals functions in high‐risk individuals of PD. This detection provides a sensitive and specific measurement of nonmotor symptoms (NMS) such as olfactory dysfunction, sleep disorders, and psychiatric symptoms in the high‐risk patients, especially at the premotor phase. Molecular imaging technique is capable of detecting the dysfunction of serotonergic, noradrenergic, and cholinergic systems that are typically associated with premotor manifestations. This review discusses the importance of SPECT/PET applications in the detection of premotor markers preceding motor abnormalities with highlighting their great potential for early and accurate diagnosis of premotor symptoms of PD and its scientific significance.     

Deep Brain Stimulation for Neuropathic Pain

Objectives. To determine whether deep brain stimulation is an effective treatment for neuropathic pain of varied etiology. Material and Methods. Thirty‐four patients with intractable neuropathic pain were prospectively studied using visual analog scores, McGill Pain Questionnaire, and Quality of Life Questionnaires (EUROQOL EQ‐5D VAS, and SF‐36 v‐2). Patients had either deep brain stimulation of either the periventricular gray or ventroposterolateral nucleus of the thalamus, or both. Results. Seventy‐six percent of patients underwent permanent implantation. Overall reduction of pain intensity was 54%. The burning component of pain improved by 77%. Health‐related quality of life improved by 38%. Conclusions. Deep brain stimulation is an effective treatment for neuropathic pain. The factors that influence outcome, including etiology and site of stimulation, are discussed.