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A model accounting for effects of vibratory amplitude on responses of cutaneous mechanoreceptors in macaque monkey

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Nevner vibrasjonens effekt på alle sensoriske nerver i huden. Gammel studie fra 80-tallet.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1250344/

1. A mechanoreceptor model, developed in the preceding paper (Freeman & Johnson, 1982), was used to study the effects of vibratory intensity and frequency on the responses of slowly adapting, rapidly adapting and Pacinian afferents in monkey hairless skin. As in the previous paper almost all of the response properties studied here were accounted for by the equivalent circuit model; changes in membrane time constant and amplitude sensitivity accounted for the differences between the three mechanoreceptive fibre types.

2. The stimulus—response function of primary concern was the relationship between impulse rate and vibratory amplitude. This relationship had the same general form in each of the three fibre types. Amplitudes, I, less than I0 produced no impulse on any stimulus cycles. Amplitudes greater than I1produced one impulse on every cycle. As I rose from I0 to I1 the impulse rate rose monotonically from 0 to 1 impulse/cycle. For each fibre type the form of this ramp depended on the stimulus frequency.

3. At stimulus frequencies low in the frequency range of each fibre type the (I0, I1) ramp tended to be steep and sigmoidal in shape. Two or more impulses occurred on some cycles and none on others.

4. At intermediate frequencies the (I0, I1) ramps became linear with at most one impulse on each cycle. A short plateau appeared at 0·5 impulses/cycle (i.e. there was a range of intensities yielding one impulse on alternate cycles). All of these response properties at low and intermediate frequencies were explained by the model.

5. At higher frequencies the (I0, I1) ramps became shallower and developed discontinuities in slope at impulse rates of 0·5 impulses/cycle. At stimulus frequencies greater than 20 Hz for SAs and RAs, the upper segment of the (I0, I1) slope became steeper. For frequencies greater than 80 Hz, the upper segments of the Pacinian (I0, I1) slopes were shallower than the lower segments. These effects suggested transient periods of hyperexcitability following each action potential, and reductions in sensitivity due to high impulse rates, respectively.

6. The model’s membrane time constant was adjusted to match the observed reduction in the (I0, I1) slope with increasing stimulus frequency. The time constants required for least-squares fitting were 58, 29 and 4·2 msec for slowly adapting, rapidly adapting and Pacinian afferents, respectively; these values are of the same order as those obtained in the preceding paper.

7. Receptor sensitivity varied across the frequency spectrum, slow adaptors being most sensitive at low frequencies, rapidly adapting units at mid-range, and Pacinians at the high frequencies. According to the model, the high frequency roll-off in a receptor’s tuning curve is due to the current integrating properties of receptor membrane, and the low frequency roll-off is due to a high pass filter, presumably mechanical, situated in the tissues between the stimulus probe and receptor membrane.

8. Impulse phase advances with increasing stimulus intensity in both receptor and model. The ability of the model to fit both the rate—intensity function and phase advance functions in individual receptors is demonstrated.

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The Effect of Surface Wave Propagation on Neural Responses to Vibration in Primate Glabrous Skin

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Studie som nevner at vibrasjon sprer seg i huden og forsterker signalene opp til hjernen. Men har bare 1 mm kontaktflate og forholder seg til høy frekvens (opp til 400 Hz)og pacini celler. Mye interessant likevel.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3278420/

«First, we find that these waves substantially amplify the neural response to the stimulus»

«Second, we show that surface waves result in a reduction of the temporal patterning in the response of afferent populations, particularly at frequencies over 200 Hz, but the degree of temporal blurring is relatively small compared to that observed in the response of S1 neurons.»

«Third, despite these two factors, the structure of the waveform is well preserved in the form of the surface waves, suggesting that surface waves should enhance the perception of simple and complex skin oscillations.»

Because tactile perception relies on the response of large populations of receptors distributed across the skin, we seek to characterize how a mechanical deformation of the skin at one location affects the skin at another.

First, we show that a vibration applied to the fingertip travels at least the length of the finger and that the rate at which it decays is dependent on stimulus frequency.

We show that this skin resonance can lead to a two-fold increase in the strength of the response of a simulated afferent population.

Second, the rate at which vibrations propagate across the skin is dependent on the stimulus frequency and plateaus at 7 m/s. The resulting delay in neural activation across locations does not substantially blur the temporal patterning in simulated populations of afferents for frequencies less than 200 Hz, which has important implications about how vibratory frequency is encoded in the responses of somatosensory neurons.

Third, we show that, despite the dependence of decay rate and propagation speed on frequency, the waveform of a complex vibration is well preserved as it travels across the skin. Our results suggest, then, that the propagation of surface waves promotes the encoding of spectrally complex vibrations as the entire neural population is exposed to essentially the same stimulus.

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Prevalence of Severe Hypovitaminosis D in Patients With Persistent, Nonspecific Musculoskeletal Pain

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Svært viktig studie som nevner hvordan d-vitamin har direkte sammenheng med ikke-spesifikke muskelsmerter. 98% av alle som fikk behandling for muskelplager hadde d-vitamin mangler, i gjennomsnitt 12 ng/ml (30nmol/L).

http://www.direct-ms.org/pdf/VitDNonAuto/VitaminDDeficiencyPain.pdf

All patients with persistent, nonspecific musculoskeletal pain are at high risk for the consequences of unrecognized and untreated severe hypovitaminosis D.

Because osteomalacia is a known cause of persistent, nonspecific musculoskeletal pain, screening all outpatients with such pain for hypovitaminosis D should be standard practice in clinical care.

Of the many types of chronic pain, nonspecific or idio- pathic musculoskeletal pain, such as noninflammatory arthritis, nonarticular rheumatism, and nonradicular low back pain, is seen frequently in medical and chiropractic clinics. Despite the prevalence, severity, and burdens of such pain, precise diagnosis and effective treatment are often elusive.

The prevalence of hypovitaminosis D was unexpectedly high in this population of nonelderly, nonhousebound, pri- mary care outpatients with persistent, nonspecific muscu- loskeletal pain refractory to standard pharmaceutical agents. Of all patients, 93% (140/150) had deficient levels of vitamin D (mean, 12.08 ng/mL; 95% confidence interval [CI], 11.18-12.99 ng/mL).

Unexpectedly, 100% of Af- rican American (n=22), 100% of American Indian (n=10), and 83% (29/35) of white patients with persistent pain also had hypovitaminosis D (mean, 11.7 ng/mL; 95% CI, 10.17- 13.27 ng/mL).

More than 90% of the patients in this study with persistent, nonspecific musculoskeletal pain were found to have deficient levels of 25-hydroxyvitamin D. Mean values were in the moderately severe to moderately deficient range. This was true regardless of immigrant status, sex, race, or season.

Even oral supplementation with vitamin D tablets may be inadequate at currently recommended doses.44-46 Up to 46% of persons found to be vitamin D–deficient have met the recommended daily intake.47-49 Also, oral supplements may not provide sufficient compensation for patients with existing hypovitaminosis D.50,51

These results support screening of all outpatients with persistent, nonspecific musculoskeletal pain for hypovitaminosis D. These patients are at high risk for the consequences of unrecognized and untreated hypovitaminosis D, and this risk extends to those now considered at low risk, including nonelderly, nonhousebound, or nonimmigrant persons of either sex

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Vitamin D Deficiency: What a Pain It Is

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Gjennomgang av d-vitamin mangler og hva det kan skape av problemer i kroppen. Nevner hva som er anbefalt mengde i blod, 30-50 ng/ml, og at man kan ta 50.000 IU 1x uka i 8 uke for å øke D-vit nivået..

http://www.anaboliclabs.com/User/Document/Articles/Vitamin%20D/5.%20Holick,%20Vit%20D,%202003.pdf

Vitamin D deficiency causes muscle weakness and muscle aches and pains in both children and adults. Glerup et al8 reported that 88% of Danish women of Arab descent who presented with muscle pains and weakness were se- verely vitamin D–deficient. Bischoff et al9 observed that adults with vitamin D deficiency have muscle weakness and are more likely to fall.

Heaney et al14 estimated that the body uses 3000 to 5000 IU/d of vitamin D. What does the body do with all that vitamin D? Most organs in the body, including the brain, heart, pancreas, skin, and immune system, recog- nize 1,25-dihydroxyvitamin D.2,7 Furthermore, many of these organs also have the capacity to make 1,25- dihydroxyvitamin D.2,7 Besides regulating calcium homeo- stasis, 1,25-dihydroxyvitamin D is a potent inhibitor of cellular growth, stimulator of insulin secretion, modulator of immune function, and inhibitor of renin production.2,7 These functions are likely responsible for the numerous epidemiological observations that people who live at higher latitudes and who are more prone to vitamin D deficiency are at increased risk of developing prostate, colon, breast, and other solid tumors15; autoimmune dis- eases including multiple sclerosis and type 1 diabetes; hy- pertension; and cardiovascular heart disease.2,7

A serum 25-hydroxyvitamin D level of at least 20 ng/mL is necessary to minimally satisfy the body’s vitamin D requirement.14,16 Maintenance of a serum 25-hydroxy- vitamin D level of 30 to 50 ng/mL is preferred.2,7,14,17 (50 ng/ml x 2,5 = 125 nmol/L)

Vitamin D deficiency can be treated easily by giving the patient an oral dose of 50,000 IU of vitamin D once a week for 8 weeks.16 Long-term prevention of vitamin D defi- ciency can be accomplished by giving 50,000 IU of vitamin D once or twice a month.

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Samling av studier om diagnoser

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En god samling studier som viser at diagnose-manien vestlig medisin og fysioterapi er bygd på ikke fungerer på mennesker med muskel og leddsmerter. (bare når det er snakk om seriøs sykdom som kreft og lignende)

Prevalence of annular tears and disc herniations on MR images of the cervical spine in symptom free volunteers.
“CONCLUSION: Annular tears and focal disk protrusions are frequently found on MR imaging of the cervical spine, with or without contrast enhancement, in asymptomatic population.”

Magnetic resonance imaging of the lumbar spine in asymptomatic adults.
“We performed magnetic resonance imaging of the lumbar spine on 66 asymptomatic subjects and found that 12 (18%) had either a disc protrusion or herniation. An additional 26 (39%) had a bulge that was associated with degenerative disc disease. We also found examples of spinal stenosis, narrowed nerve root canals, osteophytes, and vertebral body involvement with multiple myeloma. Degenerative disc disease is a common finding in asymptomatic adults that increases in frequency with age. It occurs more frequently in men and usually involves more than one level. The most common location is L5-S1.”

Dead men and radiologists don’t lie: a review of cadaveric and radiological studies of rotator cuff tear prevalence.
“CONCLUSIONS: Rotator cuff tears are frequently asymptomatic. Tears demonstrated during radiological investigation of the shoulder may be asymptomatic. It is important to correlate radiological and clinical findings in the shoulder.”

Spinal Stenosis, Back Pain, or No Symptoms at All? A Masked Study Comparing Radiologic and Electrodiagnostic Diagnoses to the Clinical Impression
“Conclusions: The impression obtained from an MRI scan does not determine whether lumbar stenosis is a cause of pain.”