Electronic thermography for the assessment of inferior alveolar nerve deficit

Facial skin temperature in acute stroke patients with delirium - A pilot study

Facial skin temperature depends strongly on blood flow in small blood vessels in the skin. These are regulated by the sympathetic part of the autonomic nervous system. Delirium may pathophysiologically be associated to changes in the sympathetic part of the autonomic nervous system. In this observational study, we evaluated the influence of various exogenous and endogenous covariables on the regional facial temperatures in acute stroke patients with and without delirium. Facial thermography (FT) was performed using an infrared digital camera. Screening for delirium was done using the Confusion Assessment Method (CAM). Sixty-four patients were enrolled. Eight patients developed delirium. Sex and body temperature were positively associated to facial skin temperature, and so was ambient temperature but to an overall lesser magnitude. Stroke severity, diabetes, infection, facial palsy, facial sensory deficit, and physical activity did not influence facial skin temperature. Overall, there was no association between facial temperature and the occurrence of delirium except in one facial region, the medial palpebral commissure.

Application of Digital Infrared Thermographic Imaging (DITI) in the Monitoring of Change of Skin Temperature about Vascular Supply of Lower Abdominal Axial Flap in the Rabbit

MethodsEight male New Zealand white rabbits with average weight of 3kg were used. A 10 x 10 cm unipedicled fasciocutaneous island flap was elevated based on the left superficial inferior epigastric vessel. The surface temperatures on designed flap were checked with DITI for 24 hours after the operation. On 14th day after the operation, the surviving area was measured and compared with DITI image which was taken on 24 hours after the operation using digital analysis software ImageJ. Statistical analysis was evaluated by paired T-test ResultsOn DITI image 24 hours after the flap elevation, distal portion of the flap showed remarkable color change. The average percentage and the standard deviation of the survival area of the flap which is predicted by DITI and the average percentage and the standard deviation of the survival area of the flap which was actually measured 2 weeks after flap elevation were 55.3 (16.6), 56.2 (18.0), respectively. This shows no significant difference between the two. ObjectivesMonitoring viability of flap is important. The flap survival depends on the vascularity of the flap, on which the skin temperature depends. The authors applied digital infrared thermographic imaging (DITI) for monitoring the vascular supply of the flap and for the prediction of the prognosis of the flap survival. MethodsEight male New Zealand white rabbits with average weight of 3kg were used. A 10 x 10 cm unipedicled fasciocutaneous island flap was elevated based on the left superficial inferior epigastric vessel. The surface temperatures on designed flap were checked with DITI for 24 hours after the operation. On 14th day after the operation, the surviving area was measured and compared with DITI image which was taken on 24 hours after the operation using digital analysis software ImageJ. Statistical analysis was evaluated by paired T-test ResultsOn DITI image 24 hours after the flap elevation, distal portion of the flap showed remarkable color change. The average percentage and the standard deviation of the survival area of the flap which is predicted by DITI and the average percentage and the standard deviation of the survival area of the flap which was actually measured 2 weeks after flap elevation were 55.3 (16.6), 56.2 (18.0), respectively. This shows no significant difference between the two. ConclusionsThis study shows that DITI system could be used in evaluation of flap vascularity with ease, quickness and safety for patient and flap. Thus, it could be used clinically for the prediction of flap survival.

Prospective study of sensation in anterior chest areas before and after a bilateral axillo-breast approach for endoscopic/robotic thyroid surgery

BACKGROUND

The bilateral axillo-breast approach for endoscopic/robotic thyroid surgery (BABA) shows good oncologic and surgical outcomes and does not result in neck scars. However, there is concern about potential sensory changes of the skin flaps after BABA, especially of the breast areas. This prospective study was undertaken to evaluate sensory changes in the skin flaps after BABA.

PATIENTS AND METHODS

A total of 19 women (mean age 36.9 ± 8.7; age range 21-51 years) who underwent BABA were enrolled. Skin flap sensory assessments were performed for each patient preoperatively and again at 1 and 3 months postoperatively. The Semmes-Weinstein monofilament test was used to evaluate the cutaneous light-pressure thresholds, a biothesiometer was used to evaluate the vibration thresholds, and an infrared thermometer was used to measure skin temperatures of the skin flaps.

RESULTS

There were changes in the sensations of the anterior chest areas over time, as determined by the Semmes-Weinstein monofilament test (1.5 vs 4.3 versus 1.4; P < 0.05) and the biothesiometer (26.8 vs 31.2 vs 22.3; P < 0.05). The sensations in the anterior chest areas normalized to preoperative levels at 3 months postoperatively. No significant differences were seen in the infrared thermometer test at any of the time points (36.2 vs 36.2 vs 36.3 °C; P = 0.9927).

CONCLUSIONS

While anterior chest area sensations were changed at 1 month postoperatively, the sensations normalized at 3 months after BABA. These results suggest that BABA has minimal adverse effects on anterior chest area sensation.

Medical applications of infrared thermography: A review

Abnormal body temperature is a natural indicator of illness. Infrared thermography (IRT) is a fast, passive, non-contact and non-invasive alternative to conventional clinical thermometers for monitoring body temperature. Besides, IRT can also map body surface temperature remotely. Last five decades witnessed a steady increase in the utility of thermal imaging cameras to obtain correlations between the thermal physiology and skin temperature. IRT has been successfully used in diagnosis of breast cancer, diabetes neuropathy and peripheral vascular disorders. It has also been used to detect problems associated with gynecology, kidney transplantation, dermatology, heart, neonatal physiology, fever screening and brain imaging. With the advent of modern infrared cameras, data acquisition and processing techniques, it is now possible to have real time high resolution thermographic images, which is likely to surge further research in this field. The present efforts are focused on automatic analysis of temperature distribution of regions of interest and their statistical analysis for detection of abnormalities. This critical review focuses on advances in the area of medical IRT. The basics of IRT, essential theoretical background, the procedures adopted for various measurements and applications of IRT in various medical fields are discussed in this review. Besides background information is provided for beginners for better understanding of the subject.

Thermography as a quantitative imaging method for assessing postoperative inflammation

OBJECTIVE

To assess differences in skin temperature between the operated and control side of the face after mandibular third molar surgery using thermography.

METHODS

127 patients had 1 mandibular third molar removed. Before the surgery, standardized thermograms were taken of both sides of the patient's face using a Flir ThermaCam™ E320 (Precisions Teknik AB, Halmstad, Sweden). The imaging procedure was repeated 2 days and 7 days after surgery. A region of interest including the third molar region was marked on each image. The mean temperature within each region of interest was calculated. The difference between sides and over time were assessed using paired t-tests.

RESULTS

No significant difference was found between the operated side and the control side either before or 7 days after surgery (p > 0.3). The temperature of the operated side (mean: 32.39 °C, range: 28.9-35.3 °C) was higher than that of the control side (mean: 32.06 °C, range: 28.5-35.0 °C) 2 days after surgery [0.33 °C, 95% confidence interval (CI): 0.22-0.44 °C, p < 0.001]. No significant difference was found between the pre-operative and the 7-day post-operative temperature (p > 0.1). After 2 days, the operated side was not significantly different from the temperature pre-operatively (p = 0.12), whereas the control side had a lower temperature (0.57 °C, 95% CI: 0.29-0.86 °C, p < 0.001).

CONCLUSIONS

Thermography seems useful for quantitative assessment of inflammation between the intervention side and the control side after surgical removal of mandibular third molars. However, thermography cannot be used to assess absolute temperature changes due to normal variations in skin temperature over time.

Thermographic imaging of facial skin--gender differences and temperature changes over time in healthy subjects

OBJECTIVES

To assess changes in facial skin temperature over time, to identify sources of variation related to skin temperature and to evaluate interobserver reproducibility in measurements of the thermograms.

METHODS

62 volunteers (32 females, 30 males, mean age 23.4, range 19.5-29.5 years) underwent thermography of the face (left and right side lateral images) on four occasions with approximately 2 months between each session. Three observers recorded the images and marked regions of interest (ROIs) in each image using dedicated software. Smoking, exercise habits and use of oral contraceptives were recorded.

RESULTS

A significant difference between sessions (≤1 °C, p<0.001) and between observers (≤0.11 °C, p<0.001) was identified. The difference between sides was not significant (≤0.07 °C, p=0.7). None of the interactions between side, session and observer were significant. Smoking, exercise habits and oral contraceptive intake were not significant impact factors when included as covariates in the analysis (p>0.1). ROI temperature was significantly higher in males than in females (0.7 °C, p<0.001). A mixed model analysis of variance showed that observer had little impact on the expected standard deviation, whereas session and subject had a greater impact.

CONCLUSIONS

Face temperature is symmetrical and varies over time. The non-significant difference between sides is highly reproducible, even between observers.

Intact cutaneous C fibre afferent properties in mechanical and cold neuropathic allodynia

Patients with neuropathy, report changes in sensory perception, particularly mechanical and thermal allodynia, and spontaneous pain. Similar sensory changes are seen in experimental neuropathies, in which alteration in primary afferent properties can also be determined. The neural correlate of spontaneous pain is ongoing activity in sensory afferents. Mechanical and heat allodynia are thought to result from lowered activation thresholds in primary afferent and/or central neurones, but the mechanisms underlying cold allodynia are very poorly understood.

We investigated nociceptive behaviours and the properties of C and A fibre intact afferents running adjacent to damaged afferents following a partial ligation injury of the saphenous nerve (PSNI). Animals developed mechanical and cold allodynia by 3 days after PSNI. Intact mechanosensitive C fibre afferents developed ongoing activity, and had slower conduction velocities 3 and 7 days following nerve injury, with no change in mechanical threshold. There was a large increase (∼46-fold) in calculated afferent input 3 days after nerve injury, as a result of the ongoing activity in these fibres. Mechano-cooling-sensitive C fibre afferents showed both enhanced cooling-evoked firing, and increased ongoing activity. The afferent barrage associated with mechano-cooling-sensitive afferents was increased 26-fold 7 days after nerve injury. We observed no differences in the properties of intact A fibre mechanosensitive afferents.

These studies demonstrate for the first time that the altered nociception seen after PSNI is associated with ongoing activity and enhanced cooling-evoked activity in intact C fibre afferents in the saphenous nerve, with no concurrent alteration in A fibre afferents.

Thermographic assessment of inferior alveolar nerve injury in patients with dentofacial deformity

PURPOSE

The purpose of this study was to evaluate the injury and recovery of the inferior alveolar nerve in orthognathic patients at 1 and 4 weeks after surgery using electronic thermography.

MATERIALS AND METHODS

Twenty subjects with Class III dentofacial deformity were studied. All patients underwent bilateral sagittal split ramus osteotomy. To image the temperature of the face, 1 anteroposterior view and 1 lateral view were taken from both the right and left sides. Similar images were taken at 1 and 4 weeks after surgery. The control was the presurgical temperature of the 20 patients who showed unilateral or bilateral nerve damage after surgery.

RESULTS

In the patients with unilateral nerve damage (n = 14), on the anteroposterior views, the temperatures of the mentum on the 2 sides differed by 0.64 degrees C at 1 week after surgery, and the difference decreased to 0.23 degrees C at 4 weeks after surgery. On the lateral images, the differences in temperature between the mentum areas were 0.10 degrees C at 1 week and 0.27 degrees C at 4 weeks after surgery. In the patients with bilateral nerve injury (n = 6), on the anteroposterior views, the temperatures of the mentum on the 2 sides differed by 0.20 degrees C at 1 week after surgery and 0.13 degrees C after 4 weeks. On the lateral views, the differences were 0.18 degrees C at 1 week and 0.34 degrees C at 4 weeks after surgery. Using the repeated measurement analysis method, the anteroposterior view showed statistically significant results in the patients with unilateral nerve damage.

CONCLUSION

The infrared body temperature method is an objective method that can be applied as a supplemental diagnostic method for inferior alveolar nerve injury.

New method for the objective evaluation of injury to the lingual nerve after operation on third molars

Existing tests of function of the lingual nerve are either subjective or, when they elicit the jaw-opening reflex, are dependent on the cooperation of the subject. We report a study in 12 healthy volunteers and 12 patients with iatrogenic injury to the lingual nerve. A bite block (containing stimulating electrodes) was held between the teeth and the tongue was held on to the electrodes by suction. When the lingual nerve was intact, an electrical stimulus elicited brief inhibition of masseteric electromyographic activity. Local analgesia and iatrogenic injury to the lingual nerve altered nerve conduction and caused a reduction in reflex inhibition. Two methods, compatible with limited numbers of applications of the stimulus, were used to quantify responses. One used an indirect measurement of intervals between action potentials of muscle and the other used a measurement of rectified signals falling below the mean amplitude before and after the stimulus. Both methods gave values that correlated with subjective sensations. The first gave an estimate of the probability of defining major malfunction of the nerve objectively; the second gave a linear measurement that allowed recovery of the nerve to be followed.

High-resolution dental magnetic resonance imaging of inferior alveolar nerve responses to the extraction of third molars

The objective of this study was to assess whether signal changes can be detected in the neurovascular bundle of the mandibular canal after the extraction of a third molar. We retrospectively analyzed MRI scans of 30 test subjects with healthy mandibles and 41 patients who had had a wisdom tooth extracted. Signal intensities were measured at particular sites in the neurovascular bundle, which were defined as regions of interest (ROI) in the sagittal T1-weighted images before and after intravenous administration of a paramagnetic contrast agent. On the basis of the signal intensity increases that were measured after contrast agent administration, we compared the signal increases obtained for the patients who had received surgical treatment with the results obtained for the population of test subjects with unremarkable mandibles ( t-test, P<0.05). Compared with the healthy test subjects, patients who had received surgical treatment showed significantly higher signal intensity increases at two measurement sites, i.e., the second molar and the second premolar ( P<0.05). We found no significant differences when the measurements were performed at the first molar ( P=0.06), the third molar ( P=0.47) and in the area of the ascending mandibular ramus ( P=0.79). Compared with a population of healthy test subjects, patients who had their third molars surgically removed show higher signal intensity increases in the neurovascular bundle after intravenous contrast agent administration. The underlying cause may be the higher blood flow in the arteries and veins and the perineural plexus, which may give evidence of the pathophysiological mechanism of nerve damage in the narrow canal as a result of osteotomy.

Thermographic imaging of postoperative inflammation modified by anti-inflammatory pretreatment

PURPOSE

The aim of this study was to assess the usefulness of thermography in detecting the postoperative inflammatory reaction after third molar removal.

PATIENTS AND METHODS

Thermographic images (NovaTherm; Novamedix Ltd, Hampshire, England) of both cheeks were obtained on the first and seventh postoperative days after removal of impacted mandibular third molars under local anesthesia in 30 patients (15 men, 15 women). The unoperated contralateral side served as a control. One of the following pretreatments was given immediately before the operation: diclofenac (Voltaren; Novartis, Espoo, Finland) 150 mg orally (rapid-release 50 mg and prolonged-release 100 mg, n = 15), diclofenac 100 mg orally (prolonged-release) and 50 mg intramuscularly (n = 11), or placebo (n = 4).

RESULTS

The postoperative skin surface temperature on the operated side was significantly higher than that on the unoperated side. The thermal difference was 0.9 degrees C +/- 0.1 degrees C on the first postoperative day and declined significantly by the seventh day to 0.3 degrees C +/- 0.1 degrees C (both P < .001). The thermal difference in patients receiving diclofenac preoperatively was significantly smaller (0.8 degrees C +/- 0.1 degrees C at day 1 and 0.2 degrees C +/- 0.1 degrees C at day 7) than in patients receiving placebo (1.6 degrees C +/- 0.1 degrees C at day 1 and 0.8 degrees C +/- 0.3 degrees C at day 7, P < .001). However, with equal doses of diclofenac, the combination of rapid-release and prolonged-release tablets orally was more effective in reducing skin temperature than an orally administered prolonged-release tablet combined with intramuscular injection (P < .001).

CONCLUSION

Thermography is a suitable method to measure the inflammatory reaction related to third molar removal. Thermal changes are significant and are decreased by the nonsteroidal anti-inflammatory drug diclofenac.

Role of thermography in the assessment of infraorbital nerve injury after malar fractures

We studied 45 patients with malar fractures who had some degree of infraorbital nerve deficit. Thermographic facial images failed to show any substantial changes in the temperature profiles of the affected and the normal control sides in relation to reco very of their facial sensation. Although some patients who had thermography on the day of injury showed significant temperature differences between the affected and the normal sides, these differences were probably the result of the acute inflammatory ch anges caused by the injury. We suggest that infrared thermography has little place in the assessment of infraorbital nerve deficits.

Lesions Of The Inferior Alveolar Nerve Arising From Endodontic Treatment

A lesion of the IAN following endodontic treatment of the lower molars and premolars is not a rare event and presents an uncomfortable situation both for the dental surgeon and the patient. Injury can result on the one hand by direct intrusion of the instrument through the apex into the mandibular canal, and on the other by the filling material which becomes forced into the mandibular canal. In the latter case, a nerve lesion will only result when the filling material contains neurotoxic substances such as paraformaldehyde. With a direct lesion or when forcing of resorbable filling material into the mandibular canal is suspected, one should first employ a wait-and-see approach, because usually the only nerve damage is in the form of neuropraxy or axonotmesis for which there is a high rate of spontaneous regeneration. However, if neurotoxic filling material is introduced into the direct vicinity of the nerves, the mandibular canal should be opened and the filling material should be removed as early as possible. If the filling material is forced directly within the endoneurium between the nerve bundles, the damaged nerve sections must be resected and bridged using transplants from the sural or greater auricular nerves.

A 6-year clinical assessment of electronic facial thermography

OBJECTIVE

To report the findings a 6-year clinical application of ET on patients with orofacial pain.

METHODS

ET was conducted (in a blinded manner) using an Agema 870 unit at 0.1 degree C thermal accuracy. A newly devised thermal classification system was applied: 'normal' when zone delta T was from 0.0 to +/-0.25 degree C, "hot' when zone delta T was > +0.35 degree C, 'cold' when zone delta T was < -0.35 degree C, and 'equivocal' when zone delta T was +/-(0.26-0.35) degree C. Study populations consisted of 164 dental patients mainly with diagnostic problems and 164 matched (control) subjects.

RESULTS

Our prospective, matched study determined that subjects with 'hot' thermograms had the clinical diagnoses of sympathetically maintained pain, peripheral nerve mediated pain, TMJ arthropathy, and maxillary sinusitis. Subjects with 'cold' thermograms were found to have the clinical diagnoses of peripheral nerve-mediated pain and sympathetically independent pain. Subjects with 'normal' thermograms were found to have the clinical diagnosis of cracked tooth syndrome, trigeminal neuralgia, pretrigeminal neuralgia, or psychogenic facial pain. The new system of thermal classification resulted in 92% (301 of 328) agreement in classification of pain patients and matched controls.

CONCLUSION

These studies suggest that ET has promise in aiding the formation of a differential diagnosis of orofacial pain and may help in understanding mechanisms of pain as well as directing therapies.