Quantitative assessment of sensory functions after 3 surgical approaches for trigeminal neuralgia by current perception threshold measurement

Objective： To quantitatively identify and grade trigeminal sensory functions after 3 major surgical procedures of trigeminal neuralgia using a newly developed quantitative sensory testing technique, current perception threshold measurement （CPTM）. Methods： In the current study, there were 48 trigeminal neuralgia patients without history of prior surgical treatment. These patients received one of the following 3 surgical procedures, microvascular decompression （MVD）, peripheral nerve block with alcohol （PNB）, or percutaneous radiofrequency thermocoagulation （PRFT）. The quantitative sensory testing measurement, CPTM, and conventional qualitative sensory testing measurements were performed preoperatively and postoperatively to evaluate and grade the trigeminal sensory functions All 3 major cutaneous sensory fiber types, large myelinated fibers （A beta）, small myelinated fibers （A delta） and unmyelinated fibers（C） were allowed to quantitatively evaluate and grade by CPTM. The results of the measurements were statistically analyzed using a one-way analysis of variance （single factor）. Each subject was his/her own control for comparison of the preoperative to postoperative state on the asymptomatic and symptomatic sides. Subjects were tested 48 h preoperatively and 4 weeks postoperatively. Results： PNB with alcohol and PRFT caused significant sensory dysfunction postoperatively in every fiber type, indicating damage to all fibers. On the contrary, the sensory function in all 3 fiber types was unchanged after MVD management. Conclusion： Among the 3 major surgical procedures tested, only MVD preserves sensory function in trigeminal system. CPTM is of quantitative nature on the evaluation of sensory functions of nerve fibers

Detecting the nerve function of fibril in patients with cervicalspondylotic radiculopathy using quantitative sensory testing

BACKGROUND: Pain and sensory disability are greatly affected by subjective factors, there are no quantitative indexes to evaluate cervical spondylotic radiculopathy(CSR). The judgment on clinical body examination and chief complaint always causes nonobjective results with great individual differences. Quantitative sensory testing (QST) can be used to judge the nerve function of fibril. The application of QST for the quantitative evaluation of peripheral nervous system disease needs to be further studied. OBJECTIVE: The cold-thermal sensation and pain of patients with CSR are quantitatively analyzed by using QST technology in order to evaluate the nerve function of fibril in patients with CSR. DESIGN: Case-control observation. SETTING: Pain Center of Beijing Hospital of Ministry of Health. PARTICIPANTS: Twenty patients with CSR, including 8 males and 12 females, aged from 33 to 70 years, who received treatment between January and April 2005 in Pain Center of Beijing Hospital of Ministry of Health were involved in CSR group. All the involved patients presented symptoms in unilateral upper extremity (left side 10 patients, right side 10 patients). They did not undergo physical therapy or nerve block therapy in 1 week before examination. Eight non-CSR patients who received treatment in Pain Center concurrently were involved in the control group (2 patients with trigeminal neuralgia, 4 with osteoarthrosis of knee joint and 2 with lumbar intervertebral disc protrusion), and another 12 healthy volunteers were involved. Four non-CSR patients and 12 healthy volunteers, 8 male and 12 female, were aged from 23 to 75 years. The informed consents were obtained from all the involved subjects. METHODS: The volar thresholds of cold sensation, thermal sensation, cryalgesia of thenar eminence of both upper extremities of all the subjects were examined separately by limit method with type TSA-Ⅱ temperature sensation analysator made by Medco Company (Israel). The subjects were pre-examined to be familiar with the method for sensory discrimination and affirmation. Thenar eminence vola of bilateral upper extremities were detected. The infrared detector of a semiconductor was contacted with skin. The infrared detector could be used to heat and cool skin. A group of cold-heat water circulation device was given electric current to produce temperature gradient, which was higher or lower than skin temperature. The initial temperature of infrared detector was 32 ℃, stimulation temperature was increased or decreased progressively at 1 ℃/s, and temperature change range was 0 to 50 ℃. In the first step, subjects pressed down the button to stop the stimulation when the temperature of infrared detector was decreased progressively until the subjects felt, and the threshold of cold sensation was obtained; In the second step, the threshold of thermal sensation was obtained when the temperature of infrared detector was increased progressively until the subjects felt; In the third step, the threshold of cryalgesia was obtained when the temperature of infrared detector was decreased progressively until subjects felt; and in the fourth step, the threshold of thermalgesia was obtained when the temperature of infrared detector was increased progressively until subjects felt. Each step was conducted 4 times and the mean threshold was obtained. Before each measurement, the temperature was made to rebound to the initial temperature and kept for 10 s. MAIN OUTCOME MEASURES: The thresholds of cold sensation, thermal sensation and cryalgesia, thermalgesia of thenar eminence vola of bilateral upper extremities of all the subjects. RESULTS: Twenty patients with CSR and 20 healthy subjects participated in the final results. ① In the CSR group, the threshold of cold sensation of affected side was lower than that of intact side [(29.00±1.26) ℃ vs.(30.00±1.06) ℃, P < 0.05], and the threshold of thermal sensation of affected side was higher than that of intact side [(35.04±0.87) ℃ vs. (34.14±0.99) ℃, P < 0.05]. There were no significant differences in the thresholds of cold and thermal sensation between affected side and intact side (P > 0.05). ②In the CSR group, the difference of threshold of cold sensation, thermal sensation, cryalgesia and thermalgesia between affected side and intact side was (-1.01±0.57), (0.89±0.39), (2.49±1.10) and (-1.62±0.86) ℃, respectively , the absolute value of which was higher than that of control group, respectively [(0.04±0.28),(0.05±0.26),(0.28±1.79),(0.17±1.10) ℃,P < 0.01]. In the CSR group, the threshold of cold sensation and thermalgesia of affected side was lower than that of intact side, respectively; and the threshold of thermal sensation and cryalgesia of affected side was higher than that of intact side, respectively. CONCLUSION: The superficial sensation of affected extremity of patients with CSR is lessened as compared with that of intact extremity. There are dysfunctions of small myelinated fiber (Aδ fiber) and demyelinated fiber (C fiber) in the affected-side extremity. QST, as a mean for quantitatively evaluating the function of Aδ fiber and C fiber, plays an objective evaluative role in the diagnosis and therapeutic effect observation of CSR.

Sensory changes, C-and A-fiber function, and shoulder-hand syndrome in hemiplegic patients after stroke

BACKGROUND： Clinical diagnosis of various neurological disorders involving the sensory nerves depends primarily on subjective description, which cannot be quantitatively evaluated, and is also less reproducible and specific. Quantitative sensory testing methods can overcome these shortcomings and is currently used to identify the function of the C- and A-fibers. OBJECTIVE： To apply the quantitative sensory testing method for analyzing changes in temperature sensation, cryalgesia, thermalgesia, and vibration sense on the skin surface of hemiplegic patients with post-stroke shoulder-hand syndrome, and to analyze the relationship between these changes and shoulder-hand syndrome. DESIGN, TIME AND SETTING： A non-randomized, concurrent, control study was performed at the Clinic and Inpatient Department of the Third Xiangya Hospital, Central South University, between June 2000 and April 2001. PARTICIPANTS： Thirty post-stroke, hemiplegic patients were divided into shoulder-hand syndrome and control groups, according to whether patients exhibited shoulder-hand syndrome, with 15 patients in each group. METHODS： A TSA2001 quantitative sensory testing device （Medoc, Israel） was used for quantitative sensory testing. All sensory testing employed limits, testing temperature sense on the palm thenar eminence and vibration sense on the thumb metacarpal. Cold threshold was ≤ 28 ℃, warmth threshold was ≥ 36 ℃, cold-evoked pain threshold was ≤ 5 ℃, heat-evoked pain threshold was ≥ 51 ℃, vibration threshold was ≥ 5 μm/s; if a patient met one of these items, he/she was considered to be hypoanesthesia. MAIN OUTCOME MEASURES： Cold, warm, cold-evoked pain, heat-evoked pain and vibration threshold changes on skin from the paralyzed upper extremity was measured in the shoulder-hand syndrome and control groups. RESULTS： Incidence of sensory disability in the shoulder-hand syndrome group increased more significantly than in the control group （P 〈 0.05）, with the primary manifestations being decreased cold threshold （P 〈 0.05） and increased warmth threshold （P 〈 0.05）. The value differences between cold and cold-evoked pain thresholds, as well as between warmth and heat-evoked pain thresholds, decreased significantly in the shoulder-hand syndrome group （P 〈 0.05）. There were no significant differences between the two groups in cold-evoked pain, heat-evoked pain, or vibration thresholds. CONCLUSION： The primary manifestations of sensory impairment in hemiplegic patients with post-stroke shoulder-hand syndrome were displayed as thermohypesthesia and hyperalgesia. Functional impairments of nerve fibers that control pain and temperature sense may play an important role in the pathogenesis of post-stroke shoulder-hand syndrome.

Abnormal endogenous pain modulation and somatic and visceral hypersensitivity in female patients with irritable bowel syndrome

AIM： To investigate the role of endogenous pain modulatory mechanisms in the central sensitization implicated by the visceral hypersensitivity demonstrated in patients with irritable bowel syndrome （IBS）. Dysfunction of modulatory mechanisms would be expected to also result in changes of somatic sensory function. METHODS： Endogenous pain modulatory mechanisms were assessed using heterotopic stimulation and somatic and visceral sensory testing in IBS. Pain intensities （visual analogue scale, VAS 0-100） during suprathreshold rectal distension with a barostat, cold pressor stimulation of the foot and during both stimuli simultaneously （heterotopic stimulation） were recorded in 40 female patients with IBS and 20 female healthy controls. RESULTS： Rectal hypersensitivity （defined by 95% Cl of controls） was seen in 21 （53%）, somatic hypersensitivity in 22 （55%） and both rectal and somatic hypersensitivity in 14 of these IBS patients. Heterotopic stimulation decreased rectal pain intensity by 6 （-11 to -1） in controls, but increased rectal pain by 2 （-3 to ＋6） in all IBS patients （P 〈 0.05） and by 8 （-2 to ＋19） in IBS patients with somatic and visceral hypersensitivity （P 〈 0.02）. CONCLUSION： A majority of IBS patients had abnormal endogenous pain modulation and somatic hypersensitivity as evidence of central sensitization.

Systematic mechanism-orientated approach to chronic pancreatitis pain

Pain in chronic pancreatitis(CP) shows similarities with other visceral pain syndromes(i.e.,inflammatory bowel disease and esophagitis),which should thus be managed in a similar fashion.Typical causes of CP pain include increased intrapancreatic pressure,pancreatic inflammation and pancreatic/extrapancreatic complications.Unfortunately,CP pain continues to be a major clinical challenge.It is recognized that ongoing pain may induce altered central pain processing,e.g.,central sensitization or pro-nociceptive pain modulation.When this is present conventional pain treatment targeting the nociceptive focus,e.g.,opioid analgesia or surgical/endoscopic intervention,often fails even if technically successful.If central nervous system pain processing is altered,specific treatment targeting these changes should be instituted(e.g.,gabapentinoids,ketamine or tricyclic antidepressants).Suitable tools are now available to make altered central processing visible,including quantitative sensory testing,electroencephalograpy and(functional) magnetic resonance imaging.These techniques are potentially clinically useful diagnostic tools to analyze central pain processing and thus define optimum management approaches for pain in CP and other visceral pain syndromes.The present review proposes a systematic mechanism-orientated approach to pain management in CP based on a holistic view of the mechanisms involved.Future research should address the circumstances under which central nervous system pain processing changes in CP,and how this is influenced by ongoing nociceptive input and therapies.Thus we hope to predict which patients are at risk for developing chronic pain or not responding to therapy,leading to improved treatment of chronic pain in CP and other visceral pain disorders.

Altered thermal sensitivity in facial skin in chronic whiplash-associated disorders

There is a close functional relationship between the jaw and neck regions and it has been suggested that trigeminal sensory impairment can follow whiplash injury.Inclusion of manageable routines for valid assessment of the facial sensory capacity is thus needed for comprehensive evaluations of patients exposed to such trauma.The present study investigated facial thermal thresholds in patients with chronic whiplash-associated disorders（WADs）with both a qualitative method and quantitative sensory testing（QST）.Ten women with pain and dysfunction following a whiplash injury were compared to 10 healthy age-matched women.Thermal detection thresholds were assessed by qualitative chair-side testing and by QST according to the method-of-limits.Seven test sites in the facial skin（overlying each trigeminal branch bilaterally,and the midpoint of the chin）were examined.The detection warm and cold thresholds were defined as the mean values of 10 individual thresholds.For the WAD patients,the qualitative assessment demonstrated both reduced and increased sensitivity compared to the healthy,whereas QST systematically showed significantly higher detection thresholds（i.e.,decreased sensitivity）for both cold and warm stimuli.For the individuals who were assessed as having increased sensitivity in the qualitative assessment,the QST displayed either normal or higher thresholds,i.e.,decreased sensitivity.The results suggest that QST is more sensitive for detecting thermal sensory disturbances in the face than a qualitative method.The impaired thermal sensitivity among the patients corroborates the notion of altered thermal detection capacity induced by WAD-related pain.

Acupuncture Treatment for Idiopathic Trigeminal Neuralgia:A Longitudinal Case-Control Double Blinded Study

Objective： To evaluate the treatment effect of acupuncture on patients with idiopathic trigeminal neuralgia（ITN） by case-control longitudinal blinded study. Methods： Sixty ITN patients and 30 healthy subjects were included. The ITN patients were randomly assigned to acupuncture group（15 cases）, sham-acupuncture group（15 cases） and carbamazepine group（30 cases）, respectively. Clinical orofacial evaluation（including pain intensity and medication doses）, research diagnostic criteria for temporomandibular disorders（RDC/TMD） and Helkimo indexes（for functional evaluation of the masticatory system）, and quantitative sensory testing for sensory thresholds（gustative, olfactory, cold, warm, touch, vibration and superficial and deep pain） were evaluated before treatment, immediately after treatment, and 6 months after treatment. Results： The mean pain intensity by the Visual Analogue Scale only decreased in the acupuncture group at the last evaluation（P=0.012）. Patients in the sham-acupuncture group had an increase in carbamazepine doses according to the prescriptions（P〈0.01）. There was a reduction in secondary myofascial pain and mandibular limitations at the acupuncture and sham-acupuncture groups, however only the acupuncture group kept the changes after 6 months（P〈0.01, P=0.023）. There was a decrease in mechanical thresholds in the acupuncture group（tactile, P〈0.01; vibration, P=0.027） and an increase in deep pain thresholds in both acupuncture and sham-acupuncture groups（P=0.013）. Conclusion： Acupuncture can be an option in the treatment of ITN due to its analgesic effect in both ITN and secondary myofascial pain associated with it.