QST in peripheral nerve injury pain disorders

Duloxetine for the management of sensory and taste alterations, following iatrogenic damage of the lingual and chorda tympani nerve

OBJECTIVES

Nerve injury may lead to pain and sensory changes such as dysesthesia and paresthesia. Quantitative sensory testing (QST) is a psychophysical testing method used to quantify nerve damage and monitor its recovery. Duloxetine is used in the management of neuropathic pain conditions, but its effect on taste recovery has not been previously reported.

CASE REPRESENTATION

A 65-year-old female, presented to the orofacial pain clinic, with a chief complaint of a burning sensation on the tongue, taste changes and a feeling of tightness beneath the tongue for five months. She reported that the complaints began subsequent to a complicated dental extraction during which she experienced trauma to the tongue. Patient was advised to take duloxetine 60 mg in divided doses three times daily. The assessment and monitoring of the recovery pattern were performed using QST. Electrical taste detection (mediated by chorda tympani) and electrical detection/tingling thresholds were performed at periodic intervals for up to a year following the nerve injury in the chorda tympani and lingual nerve territory. The patient reported complete recovery in taste sensation with duloxetine and this correlated with the QST results. QST documented at the end of one year revealed the electrical taste detection threshold and electrical detection threshold return to near normal values.

CONCLUSIONS

QST may be a useful diagnostic tool to assess and monitor lingual and chorda tympani nerve injuries. Duloxetine may aid in the recovery of the taste changes following lingual and chorda tympani nerve injury.

Association of serum Ninjurin2 levels with neurologic damage and postherpetic neuralgia occurrence: an observational cohort study in chinese herpeszoster patients

Objectives

Postherpetic neuralgia(PHN) is the most common complication of herpeszoster (HZ) infection. The study aimed to explore whether serum Ninjurin2 (for nerve injury-induced protein 2, NINJ2), a novel neurologic damage related protein, is associated with nerve injury and the occurrence of PHN.

Results

Seventy-four of the eighty patients completed the study. On the 7th day of AHN, the patients had significantly higher values of NINJ2, cold-sense dispersion (ΔCS), warm-sense dispersion (ΔWS), cold-pain dispersion (ΔCP), heat-pain dispersion (ΔHP) and NRS score compared to controls. Six months after herpes, thirty four patients developed PHN. The values of serum NINJ2, ΔCS, ΔWS, ΔCP and ΔHP in PHN patients remained higher than in the controls and the patients who did not develop PHN. The PHN patients had significantly lower values of serumNINJ2 than patients who did not develop PHN in the period of AHN. With partial correlations and multivariable logistic regressions, serum NINJ2 level was strongly predictive of PHN.

Materials and Methods

Eighty individuals with acute herpetic neuralgia (AHN) and 60 controls were recruited. The following nerve injury testing was performed on all of the patients including: the numerical rating scale (NRS) test, quantitative sensory testing (QST), and the investigation of serum NINJ2 levels on the 7th day of AHN; in addition, all of the patients repeated all of the items at 6 months after herpes.

Conclusions

The serum NINJ2 levels are associated with nerve injury, particularly with nerve recovery, and may be predictors of PHN occurrence.

The effect of acupuncture needle combination on central pain processing--an fMRI study

Background

Empirical acupuncture treatment paradigm for acute pain utilizing Tendinomuscular Meridians (TMM) calls for the stimulation of Ting Points (TPs) and Gathering point(GP). This study aims to compare the supraspinal neuronal mechanisms associated with both TPs and GP needling (EA3), and TPs needling alone (EA2) with fMRI.

Results

A significant (P < 0.01) difference between pre-scan (heat Pain) HP, and post-EA HP VAS scores in both paradigms was noted (n = 11). The post-EA HP VAS score was significantly (P < 0.05) lower with EA3 comparing to EA2 Within-group random effect analysis indicated that EA3+HP>EA3 (condition EA3+HP subtracted by condition EA3) appeared to exert a significant degree of activity suppression in the affective supraspinal regions including the IPL, anterior cingulate cortex (ACC) and the insular cortex (IN). This level of suppression was not observed in the EA2+HP>EA2 (condition EA2+HP subtracted by condition EA2) within-group random effect analysis Between-group random effect analysis indicated that EA3 induced a significantly (P < 0.01, cluster size threshold 150) higher degree of deactivation than EA2 in several pain related supraspinal regions including the right prefrontal cortex, rostral anterior cingulate (rACC), medial cingulate cortex, left inferior frontal lobe and posterior cerebellum. The 2-factor ANOVA in those regions indicated both rACC and posterior cerebellum had a significant (P < 0.01) needle effect, and the right prefrontal area showed a significant (P < 0.01) HP effect. However, a significant interaction between the two factors was only found in the right prefrontal lobe. Granger causality analysis showed EA3 induced a much higher degree of inference among HP related supraspinal somatosensory, affective and modulatory components than EA2. Deactivation pattern at the medullary-pontine area casted a direct inference on the deactivation pattern of secondary somatosensory cortices which also affected the deactivation of the IN.

Conclusions

While both EA2 and EA3 induced a significant degree of deactivation in the human brain regions related to pain processing, the addition of GP stimulation further exerts an inhibitory effect on the ascending spinoreticular pain pathway. Therefore, different needling position as mandated in different empirical acupuncture treatment paradigms may play a different role in modulating pain related neuronal functions.