Limb Hypothermia for Preventing Paclitaxel-Induced Peripheral Neuropathy in Breast Cancer Patients: A Pilot Study

BACKGROUND

Peripheral neuropathy (PN) due to paclitaxel is a common dose-limiting toxicity with no effective prevention or treatment. We hypothesize that continuous-flow limb hypothermia can reduce paclitaxel-induced PN.

PATIENTS AND METHODS

An internally controlled pilot trial was conducted to investigate the neuroprotective effect of continuous-flow limb hypothermia in breast cancer patients receiving weekly paclitaxel. Patients underwent limb hypothermia of one limb for a duration of 3 h with every paclitaxel infusion, with the contralateral limb used as control. PN was primarily assessed using nerve conduction studies (NCSs) before the start of chemotherapy, and after 1, 3, and 6 months. Skin temperature and tolerability to hypothermia were monitored using validated scores.

RESULTS

Twenty patients underwent a total of 218 cycles of continuous-flow limb hypothermia at a coolant temperature of 22°C. Continuous-flow limb hypothermia achieved mean skin temperature reduction of 1.5 ± 0.7°C and was well tolerated, with no premature termination of cooling due to intolerance. Grade 3 PN occurred in 2 patients (10%), grade 2 in 2 (10%), and grade 1 in 12 (60%). Significant correlation was observed between amount of skin cooling and motor nerve amplitude preservation at 6 months (p < 0.0005). Sensory velocity and amplitude in the cooled limbs were less preserved than in the control limbs, but the difference did not attain statistical significance. One patient with a history of diabetes mellitus had significant preservation of compound muscle action potential in the cooled limb on NCS analysis.

CONCLUSION

This study suggests that continuous limb hypothermia accompanying paclitaxel infusion may reduce paclitaxel-induced PN and have therapeutic potential in select patients and warrants further investigation. The method is safe and well tolerated.

Low Levels of NDRG1 in Nerve Tissue Are Predictive of Severe Paclitaxel-Induced Neuropathy

Introduction

Sensory peripheral neuropathy caused by paclitaxel is a common and dose limiting toxicity, for which there are currently no validated predictive biomarkers. We investigated the relationship between the Charcot-Marie-Tooth protein NDRG1 and paclitaxel-induced neuropathy.

Methods/Materials

Archived mammary tissue specimen blocks of breast cancer patients who received weekly paclitaxel in a single centre were retrieved and NDRG1 immunohistochemistry was performed on normal nerve tissue found within the sample. The mean nerve NDRG1 score was defined by an algorithm based on intensity of staining and percentage of stained nerve bundles. NDRG1 scores were correlated with paclitaxel induced neuropathy

Results

111 patients were studied. 17 of 111 (15%) developed severe paclitaxel-induced neuropathy. The mean nerve NDRG1 expression score was 5.4 in patients with severe neuropathy versus 7.7 in those without severe neuropathy (p = 0.0019). A Receiver operating characteristic (ROC) curve analysis of the mean nerve NDRG1 score revealed an area under the curve of 0.74 (p = 0.0013) for the identification of severe neuropathy, with a score of 7 being most discriminative. 13/54 (24%) subjects with an NDRG1 score < = 7 developed severe neuropathy, compared to only 4/57 (7%) in those with a score >7 (p = 0.017).

Conclusion

Low NDRG1 expression in nerve tissue present within samples of surgical resection may identify subjects at risk for severe paclitaxel-induced neuropathy. Since nerve biopsies are not routinely feasible for patients undergoing chemotherapy for early breast cancer, this promising biomarker strategy is compatible with current clinical workflow.

Hypothermia for preventing chemotherapy-induced neuropathy - a pilot study on safety and tolerability in healthy controls

INTRODUCTION

Chemotherapy-induced peripheral neuropathy (CIPN) is a major dose-limiting side effect of several chemotherapeutic agents, often leading to treatment discontinuation. Up to 20% of patients treated with weekly paclitaxel experience severe CIPN and no effective treatment has been established so far. The mechanisms of CIPN damage are unclear, but are directly dose-related. We had earlier demonstrated, in rats, the influence of hypothermia in reducing nerve blood flow. Here, we hypothesize that continuous flow limb hypothermia during chemotherapy reduces the incidence and severity of CIPN, by limiting deliverance of the neurotoxic drug to the peripheral nerves. In this study, prior to assessing the effect of hypothermia in preventing CIPN in cancer subjects undergoing paclitaxel chemotherapy, we assess the safety and tolerable temperatures for limb hypothermia in healthy human subjects.

MATERIAL AND METHODS

In 15 healthy human subjects, hypothermia was administered as continuous flow cooling, unilaterally, via a thermoregulator setup covering the digits up to the elbow/knee, along with continuous skin temperature monitoring. Thermoregulator coolant temperatures between 25 °C and 20 °C were tested for tolerability, based on a carefully designed temperature regulation protocol, and maintained for three hours mimicking the duration of chemotherapy. Tolerability was evaluated using various safety and tolerability scores to monitor the subjects.

RESULTS

At the end of the cooling session the healthy subjects presented without significant adverse effects, the main being brief mild skin erythema and transient numbness. Coolant temperatures as low as 22 °C were well tolerated continuously over three hours.

CONCLUSION

Our results confirm the safety and tolerability of continuous flow limb hypothermia in healthy subjects. Further studies will use 22 °C thermoregulator temperature to investigate hypothermia in preventing CIPN in breast cancer patients receiving adjuvant weekly paclitaxel. This pilot study may contribute to alleviating chemotherapy dose limitation due to CIPN and increase the likelihood of success of chemotherapy.

Frequency-domain EEG source analysis for acute tonic cold pain perception

OBJECTIVE

To investigate electrocortical responses to tonic cold pain by frequency-domain electroencephalogram (EEG) source analysis, and to identify potential electrocortical indices of acute tonic pain.

METHODS

Scalp EEG data were recorded from 26 healthy subjects under tonic cold pain (CP) and no-pain control (NP) conditions. EEG power spectra and the standardized low-resolution brain electromagnetic tomography (sLORETA) localized EEG cortical sources were compared between the two conditions in five frequency bands: 1-4 Hz, 4-8 Hz, 8-12 Hz, 12-18 Hz and 18-30 Hz.

RESULTS

In line with the EEG power spectral results, the source power significantly differed between the CP and NP conditions in 8-12 Hz (CP<NP) and 18-30 Hz (CP>NP) in extensive brain regions. Besides, there were also significantly different 4-8 Hz and 12-18 Hz source activities between the two conditions. Among the significant source activities, the left medial frontal and left superior frontal 4-8 Hz activities, the anterior cingulate 8-12 Hz activity and the posterior cingulate 12-18 Hz activity showed significant negative correlations with subjective pain ratings.

CONCLUSIONS

The brain's perception of tonic cold pain was characterized by cortical source power changes across different frequency bands in multiple brain regions. Oscillatory activities that significantly correlated with subjective pain ratings were found in the prefrontal and cingulate regions.

SIGNIFICANCE

These findings may offer useful measures for objective pain assessment and provide a basis for pain treatment by modulation of neural oscillations at specific frequencies in specific brain regions.

EEG-based mental fatigue measurement using multi-class support vector machines with confidence estimate

OBJECTIVE

Automatic measurement and monitoring of mental fatigue are invaluable for preventing mental-fatigue related accidents. We test an EEG-based mental-fatigue monitoring system using a probabilistic-based support vector-machines (SVM) method.

METHODS

Ten subjects underwent 25-h sleep deprivation experiments with EEG monitoring. EEG data were segmented into 3-s long epochs and manually classified into 5 mental-fatigue levels, based on subjects' performance on an auditory vigilance task (AVT). Probabilistic-based multi-class SVM and standard multi-class SVM were compared as classifiers for distinguishing mental fatigue into the 5 mental-fatigue levels.

RESULTS

Accuracy of the probabilistic-based multi-class SVM was 87.2%, compared to 85.4% using the standard multi-class SVM. Using confidence estimates aggregation, accuracy increased to 91.2%.

CONCLUSIONS

Probabilistic-based multi-class SVM not only gives superior classification accuracy but also provides a valuable estimate of confidence in the prediction of mental fatigue level in a given 3-s EEG epoch.

SIGNIFICANCE

The work demonstrates the feasibility of an automatic EEG method for assessing and monitoring of mental fatigue. Future applications of this include traffic safety and other domains where measurement or monitoring of mental fatigue is crucial.

A feature selection method for multilevel mental fatigue EEG classification

Two feature selection approaches for multilevel mental fatigue electroencephalogram (EEG) classification are presented in this paper, in which random forest (RF) is combined with the heuristic initial feature ranking scheme (INIT) or with the recursive feature elimination scheme (RFE). In a "leave-one-proband-out" evaluation strategy, both feature selection approaches are evaluated on the recorded mental fatigue EEG time series data from 12 subjects (each for a 25-h duration) after initial feature extractions. The latter of the two approaches performs better both in classification performance and more importantly in feature reduction. RF with RFE achieved its lowest test error rate of 12.3% using 24 top-ranked features, whereas RF with INIT reached its lowest test error rate of 15.1% using 64 top-ranked features, compared to a test error rate of 22.1% using all 304 features. The results also show that 17 key features (out of 24 top-ranked features) are consistent between the subjects using RF with RFE, which is superior to the set of 64 features as determined by RF with INIT.

Second lumbrical-interossei latency difference: A strong predictor of median neuropathy at the wrist in uremic patients

PURPOSE

Hand symptoms in uremic patients on dialysis can occur due to peripheral neuropathy, median neuropathy at wrist (carpal tunnel syndrome) or a combination. Routine electrophysiological parameters for diagnosing carpal tunnel syndrome do not differentiate median neuropathy at wrist in cases with concomitant peripheral neuropathy. Measuring 2L-INT latency difference has been described as the most sensitive test in establishing median neuropathy at wrist in cases with severe carpal tunnel syndrome and concomitant peripheral neuropathy. This study tested the significance of 2L-INT latency difference as a predictor of median neuropathy at wrist in uremic patients on dialysis.

METHODS

80 consecutive cases (158 hands) of end-stage renal failure on either hemodialysis or peritoneal dialysis were subjected to routine electrophysiological studies for carpal tunnel syndrome. 2L-INT latency difference was measured in all cases.

RESULTS

132/158 hands (83.5%) had abnormal electrophysiological studies. Routine tests were consistent with neurophysiological carpal tunnel syndrome in 66 (41.8%) hands and 63 of these 66 (95.5%) had prolonged 2L-INT latency difference. Peripheral neuropathy was found in 66 (41.8%) hands but 59 out of these 66 (89.4%) had prolonged 2L-INT latency difference suggesting a concomitant median neuropathy at wrist. Routinely performed tests would have missed median neuropathy at wrist with concomitant peripheral neuropathy in 59 (37.3%) hands. Overall, the incidence of median neuropathy at the wrist in our uremic patients on maintenance dialysis using standard nerve conduction parameters was 41.8%, however the incidences increased substantially to 79.1% if 2L-INT latency difference is included in the criteria for the diagnosis.

CONCLUSIONS

Median neuropathy at wrist is common in patients with end-stage renal failure patients on dialysis. Diagnosis of median neuropathy at wrist is difficult in the presence of peripheral neuropathy when using the routine electrophysiological tests. Second Lumbrical-Interossei latency difference is a sensitive electrophysiological test to predict median neuropathy at wrist in presence of peripheral neuropathy.

Characteristic EEG differences between voluntary recumbent sleep onset in bed and involuntary sleep onset in a driving simulator

OBJECTIVE

To investigate the differences in electroencephalographic (EEG) characteristics for voluntary sleep onset in bed sleeping and involuntary sleep onset in driving.

METHODS

EEG measurement and analysis on 20 human subjects were conducted during recumbent bed sleeping as well as involuntary sleeping during a simulated driving platform. Each experiment was conducted on separate days.

RESULTS

Vertex and spindle waves showed differing morphology under each condition. Vertex sharpness during recumbent sleep onset was significantly sharper than involuntary sleep onset during simulated driving. Sharpness of vertices from night-driving was significantly sharper than with day-driving. Triple conjoined vertex waves only occurred with voluntary recumbent sleep onset. A conjoined vertex spindle waveform was statistically associated with sleep onset whilst driving.

CONCLUSIONS

This study has identified distinctive differences in EEG graphoelements during the sleep onset phase of recumbent and simulated driving conditions suggesting that EEG graphoelements are affected by cortical processes and vary according to the prevalent sleep condition.

SIGNIFICANCE

This study could provide a further basis for developing safety alerting devices for the detection of sleep onset in the hope of improving driving safety.

An auditory vigilance task for mental fatigue detection

An Auditory Vigilance Task (AVT) as a validation criterion for monitoring mental fatigue was proposed in this study. The biological basis of this task design is on the understanding that mental fatigue is a cortical deactivation. This AVT is simple to perform, free of learning curve and independent on acquired skills (aptitude, knowledge). The validity and sensitivity of this task was verified by a scientifically controlled 25-hour fatigue experiment recorded by Electroencephalogram (EEG). Results showed that this AVT is highly sensitive to changes during fatigue process. The effectiveness of this AVT was compared to one subjective rating scale (FSS). The 5-level fatigue EEG datasets (labeled by AVT and FSS respectively) were fed into Support Vector Machines (SVM). SVM test accuracy indicated that AVT is more effective than subject's own estimation. The results demonstrate conclusively that this AVT is suitable for fatigue detection study as a reliable validation criterion.

Computer-based versus pen-and-paper testing: students' perception

BACKGROUND

Computer-based testing (CBT) has become increasingly popular as a testing modality in under- and postgraduate medical education. Since 2004, our medical school has utilised CBT to conduct 2 papers for the third- and final-year assessments - Paper 3, with 30 multiple choice questions featuring clinical vignettes, and the modified essay question (MEQ) paper.

AIMS

To obtain feedback from final-year students on their preferred mode of testing for Paper 3 and MEQ components of the Medicine track examination, and the reasons underlying their preferences.

METHODS

An online survey was carried out on 213 final-year undergraduates, in which they were asked to provide feedback on Paper 3 and MEQ papers. Students were asked if they thought that the CBT format was preferable to the pen-and-paper (PNP) format for Paper 3 and the MEQ, and why.

RESULTS

One hundred and fourteen out of 213 (53.5%) students completed the online survey. For Paper 3, 91 (79.8%) felt that CBT was preferable to PNP, 11 (9.6%) preferred the PNP format and 12 (10.5%) were unsure. For the MEQ, 62 (54.4%) preferred CBT over PNP, 30 (26.3%) preferred the PNP format and 22 (19.3%) were unsure. Reasons given to explain preference for CBT over PNP for Paper 3 included independence from seating position, better image quality (as images were shown on personal computer screens instead of projected onto a common screen) and the fact that CBT allowed them to proceed at their own pace. For the MEQ, better image quality, neater answer scripts and better indication of answer length in CBT format were cited as reasons for their preference.

CONCLUSIONS

Our survey indicated that whereas the majority of students preferred CBT over PNP for Paper 3, a smaller margin had the same preference for the MEQ.

Comparison of a simple method for quantitation of intraepidermal nerve fibres with a standard image analysis method using hypothenar skin

OBJECTIVES

To compare a simpler method for counting intraepidermal nerve fibres with a standard computer based image analysis method in normal subjects with skin taken from the hypothenar region.

METHODS

In 40 healthy controls (mean age 41.1 years, range 21-71, 24 Chinese, 11 Indian, 5 Malay, 30 females) intraepidermal nerve fibres per length of epidermis were determined using immunoperoxidase staining with the panaxonal antibody PGP 9.5. Under brightfield microscopy, two methods of determining the length of the epidermis were compared. A simpler method employing a microscope intraocular lens ruler was compared with the more complex gold standard using image software analysis .

RESULTS

Intraepidermal nerve fibres per length of epidermis using the intraocular ruler method were 3.07 nerve fibres/mm (2SD 1.56). The image software analysis obtained values of 3.05 nerve fibres/mm (2SD 1.54). Correlation between the two tests was excellent (r=0.999 p= or <0.00001). Epidermal nerve fibre counts from hypothenar skin are lower than in more proximal sites.

CONCLUSION

A simple method for counting intraepidermal nerve fibres produces results similar to those using standard software image analysis. This should help the implementation of this technique for wider use.

Headaches and the N95 face-mask amongst healthcare providers

Background:  During the 2003 severe acute respiratory distress syndrome epidemic, healthcare workers mandatorily wore the protective N95 face‐mask.

Methods:  We administered a survey to healthcare workers to determine risk factors associated with development of headaches (frequency, headache subtypes and duration of face‐mask wear) and the impact of headaches (sick days, headache frequency and use of abortive/preventive headache medications).

Results:  In the survey, 212 (47 male, 165 female) healthcare workers of mean age 31 years (range, 21–58) participated. Of the 79 (37.3%) respondents who reported face‐mask‐associated headaches, 26 (32.9%) reported headache frequency exceeding six times per month. Six (7.6%) had taken sick leave from March 2003 to June 2004 (mean 2 days; range 1–4 days) and 47 (59.5%) required use of abortive analgesics because of headache. Four (2.1%) took preventive medications for headaches during this period. Multivariate logistic regression showed that pre‐existing headaches [P = 0.041, OR = 1.97 (95% CI 1.03–3.77)] and continuous use of the N95 face‐mask exceeding 4 h [P = 0.053, OR = 1.85 (95% CI 0.99–3.43)] were associated with development of headaches.

Conclusions:  Healthcare providers may develop headaches following the use of the N95 face‐mask. Shorter duration of face‐mask wear may reduce the frequency and severity of these headaches.

A blessing in disguise: Resolution of tardive dyskinesia with development of cervical myelitis

Tardive dyskinesia (TD), which is frequently seen in patients treated with dopamine receptor blocking agents, is difficult to manage. We report on a young Chinese man with bipolar disorder who developed TD after haloperidol treatment, involving the trunk, limbs, and orofacial area. TD persisted despite switching to atypical antipsychotic agents and treatment with valproate, benzodiazepines, and tetrabenazine. Resolution only occurred years later when he developed quadriplegia arising from infective myelitis of the cervical cord (C4-5). He had concomitant vertebral osteomyelitis, which was successfully treated with intravenous antibiotics. With intensive rehabilitation, he recovered the use of his limbs, but had no recurrence of TD. We attribute the resolution of orofacial dyskinesias with a cervical lesion to the interconnections between the orofacial area and cervical spine via the trigeminal nucleus (which has fibers descending as far caudally as C6), as well as to resetting of cortical maps.

Topical botulinum toxin to treat hyperhidrosis? No sweat!

Palmar, plantar and axillary hyperhidrosis, though benign, may be burdensome and occupationally restrictive, even hazardous. Treatment modalities range from topical antiperspirants, iontophoresis, systemic medications such as anticholinergics and benzodiazepines and injections of botulinum toxin, to thoracic sympathectomy. Intradermal injections of botulinum toxin (BTX), though effective, are painful especially when multiple injections are required. Iontophoretic administration of BTX has been described, the BTX entering the eccrine sweat glands via the sweat pores and through the sweat ducts. We postulate that BTX can be administered topically, either unassisted or assisted by application of an electrical gradient, low-frequency ultrasound or excipients such as dimethylsulfoxide. We examine the rationale and feasibility for such a treatment modality and route of administration.

Dystonia gravidarum: A new entity?

We describe cervical dystonia occurring in a 31-year-old, previously well, primigravid, primiparous Chinese woman at 4 weeks' amenorrhea, which was ameliorated with low-dose clonazepam and disappeared completely by the end of the second trimester without recurring despite her being tapered off benzodiazepine therapy. Investigations were unremarkable for structural and biochemical causes of dystonia. Chorea, paraballismus, and restless legs syndrome are known to occur during pregnancy, attributable to high estrogen levels. Dystonia, on the other hand, has not been described to occur de novo in pregnancy. This association should be considered in women of reproductive age who present with cervical dystonia.

Acute transverse myelitis following dengue virus infection

The spinal cord is infrequently affected following dengue virus infection. We report a case of transverse myelitis that developed 2 weeks after acute dengue infection and review the literature to elucidate the pathogenesis of spinal cord involvement in dengue infection. We postulate that temporal factors may play a role in the different clinical manifestations, i.e. that acute parainfectious dengue infection presents with flaccid paralysis, whereas late-stage (postinfectious) dengue infection, presents with spastic weakness. Further studies need to be performed to elucidate the mechanisms of spinal neurological damage in dengue.

The NORSE (new-onset refractory status epilepticus) syndrome: defining a disease entity

INTRODUCTION

To characterise a homogeneous group of patients with new-onset refractory status epilepticus (NORSE syndrome).

MATERIALS AND METHODS

This is a descriptive, semiprospective review of all cases of NORSE syndrome seen between 2000 and 2004 at a tertiary care public hospital in Singapore. A review of the literature was performed to identify possible additional similar cases for comparison.

RESULTS

Seven patients with NORSE syndrome were identified. Characterising features were female gender, young age, previous good health, cerebrospinal fluid pleocytosis (in 4), antecedent febrile illness (in 5), extraordinarily prolonged status epilepticus (average 32 days), failure of extensive investigations to reveal an underlying cause, catastrophic outcome as well as temporal lobe and leptomeningeal abnormality on brain magnetic resonance imaging. A review of the literature identified 12 similar patients, comprising both adults and children.

CONCLUSIONS

Based on our patients and those described in the literature, we characterise the NORSE syndrome. Increased recognition of this clinical entity is needed to help delineate the underlying aetiology of this unique severe illness.

Generalised myoclonus evolving into epilepsia partialis continua due to a cingulate gyrus lesion: case report and review of the literature

A young Chinese male was admitted for a generalised tonic-clonic seizure preceded by a week-long history of fever. Subsequently, he developed continuous myoclonic jerks in all four limbs, with clear left sided predominance, and no accompanying clouding of consciousness. Contrast MRI of the brain demonstrated a venous angioma in the right cingulate gyrus. Over the next few days, the clinical picture evolved, with focal motor status involving primarily the left lower limb and the abdomen. These movements resolved with anticonvulsant therapy. This case illustrates generalised myoclonus arising from a focal brain abnormality. The epileptiform aetiology became obvious only after evolution into the typical features of a focal motor seizure and supportive neuroimaging. This demonstrates the protean manifestations of epileptic seizures which have been ascribed to the cingulate gyrus. The lack of clear declarative clinical and EEG features highlights the melding of the fields of epileptology and movement disorders.

Water immersion wrinkling--physiology and use as an indicator of sympathetic function

Water immersion skin wrinkling is an indicator of limb sympathetic function. Routine clinical usage of this enigmatic phenomenon is hampered by poor endpoint quantification, which involves counting skin folds. The recent discovery of the importance of vasoconstriction in immersion wrinkling suggests digital blood flow or volume changes as better endpoints. Water probably initiates the wrinkling process by altering epidermal electrolyte homeostasis as it diffuses into the porous skin of the hands and soles via its many sweat ducts. Altered epidermal electrolyte homeostasis would lead to a change in membrane stability of the surrounding dense network of nerve fibers and trigger increased vasomotor firing with subsequent vasoconstriction. Vasoconstriction, through loss of volume, leads to negative digit pulp pressure resulting in a downward pull on the overlying skin, which wrinkles as it is distorted. The degree of wrinkling would directly depend on the change in digit tip volume and implies any process inducing loss of digit volume will precipitate wrinkling. This review discusses the physiology of water immersion wrinkling and explores its potential as an indicator of limb sympathetic dysfunction.

Vasomotor dysfunction in carpal tunnel syndrome

Little attention has been paid to small-fiber dysfunction in carpal tunnel syndrome (CTS) although its symptoms are common. This study investigates vasomotor dysfunction, which is controlled by small nerve fibers, in patients with CTS compared with control subjects. Vasomotor function was quantified by measuring, with laser Doppler velocimetry, skin vasoconstriction induced by a eutectic mixture of local anesthetic (EMLA) cream over digit tips 3, 4, and 5. Hands with CTS (n = 32) compared with controls (n = 19) demonstrated significantly reduced vasoconstriction in digits 3 and 4, but not digit 5. A blood flow ratio (digit 3/5) of less than 0.73 identified CTS in 69% with 68% specificity. Testing for vasomotor dysfunction in CTS allows for more comprehensive neurophysiological testing, which is heavily biased towards large nerve fibers.

Water-immersion wrinkling is due to vasoconstriction

The underlying mechanism of the water-immersion skin wrinkling test, which is used as a test of sympathetic nerve function, remains elusive. We investigated changes of blood circulation in the hand occurring with water-immersion wrinkling by measuring the velocity of ulnar and digital artery blood flow, and of digit skin blood flow, in healthy subjects before and during wrinkling. Wrinkling was accompanied by significant reduction in blood flow velocity in all vessels, with a maximum in digital vessels. Our data show that water-immersion wrinkling is a function of digit pulp vasoconstriction. This test of sympathetic function can now be quantified using parameters of blood flow velocity, enabling its more widespread and accurate use.