Assessment of Progression-Free-Survival in Glioblastomas by Intratreatment Dynamic Contrast-Enhanced MRI.

PURPOSE: The efficacy of concomitant chemoradiation in patients with glioblastomas (GBMs) cannot be reliably assessed until several weeks after therapy completion. Our aim was to evaluate dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) as an early predictive assay for the progression-free-survival. METHODS AND MATERIALS: A total of 22 patients with primary GBMs underwent DCE-MRI before, during and after completion of adjuvant chemoradiation. K (trans) (transfer constant between the intravascular and extravascular, extracellular space), v(e) (extracellular, extravascular volume) and IAUGC (initial area under the gadolinium concentration time curve) and their changes into treatment were assessed as prognostic markers (12 months of progression-free-survival (PFS)). RESULTS: Both responders (7 subjects) and non-responders (15 subjects) experienced a reduction in the baseline IAUGC and v(e) values during the early phase of the treatment. This reduction was more prominent in the responders and was statistically significant for the v(e) (P = 0.04). Baseline K (trans) values among responders demonstrated statistically significant reduction during the early phase of treatment (P = 0.001). Multivariate Cox regression analysis demonstrated significant relationship between response and the early changes in K (trans) values during the treatment (P = 0.04). Trend to significant prognostic value demonstrated the baseline K (trans), v(e) and IAUGC as well as the changes of IAUGC and K (trans) upon therapy completion. CONCLUSIONS: Early perfusion changes during concomitant chemoradiation in GBMs can be detected by means of DCE-MRI and have significant prognostic value for the 12-month PFS.

Autonomic dysfunction in presymptomatic and early symptomatic Huntington's disease.

OBJECTIVES: Although autonomic dysfunction was found in advanced Huntington's disease (HD) patients it is not clear whether there is autonomic dysfunction in presymptomatic and early symptomatic HD. MATERIAL & METHODS: Different cardiovascular autonomic tests were performed in 14 presymptomatic HD mutation carriers (PHD), 11 early symptomatic HD patients (EHD) and in 25 sex and age matched controls. RESULTS: We found attenuated response to simple mental arithmetic test (relative heart rate in PHD and EHD was 10% lower than in controls; diastolic pressure was 10.6% lower in EHD than in controls; P < 0.05) and exaggerated response to the late phase of cold pressor test (relative heart rate was 10% higher in PHD and 7% higher in EHD than in controls; P < 0.05). The rest of the cardiovascular autonomic tests did not reveal significant differences between patients and controls. CONCLUSIONS: Our results suggest that subtle autonomic dysfunction occurs even in PHD and EHD.

Ingrowth of sensory axons into an end-to-side coapted nerve stump after donor nerve crush in the rat.

BACKGROUND: Target innervation through an end-to-side (ETS) nerve coaptation depends on axonal sprouting from the donor nerve. Terminal axonal sprouting in a partially denervated target tissue is more extensive from a crushed donor nerve than from an intact donor nerve. We hypothesized that axonal sprouting into an ETS coapted recipient nerve could be stimulated by crushing the donor nerve. METHOD: Twenty-seven rats were randomised into 3 groups. In all, the distal stump of the transected peroneal nerve was sutured to the side of the sural nerve in place of the epineural window. The control group received no additional treatment. In the experimental groups, the sural donor nerve was crushed either 8 mm proximal (proximal crush group) or 8 mm distal to the coaptation site (distal crush group). Sixteen weeks after the surgery, histomorphometric analysis of the recipient peroneal nerve stump 4 mm distal to the coaptation site was performed. FINDINGS: The number of myelinated axons in the recipient peroneal nerve stump was 758 +/- 247 in the control group, 503 +/- 246 in the distal crush group and 211 +/- 96 in the proximal crush group. The differences between the groups were statistically significant (p < 0.05). The majority of myelinated axons were thin myelinated axons and the frequency distribution of their cross-sectional areas was similar in all groups. CONCLUSION: Contrary to our expectations, a significantly lower number of myelinated axons were present in recipient nerves in the proximal and distal crush groups than in the control group. This suggests that sensory axon ingrowth into an ETS coapted nerve cannot be enhanced by crushing the donor nerve.

Which myelinated sensory axons sprout into an end-to-side coapted peripheral nerve in the rat?

BACKGROUND: The high-threshold sensory afferents, which express trkA, are predominantly involved in terminal collateral sprouting in the skin of adult mammals. We explored which sensory axons are capable of sprouting into the end-to-side coapted nerve in the rat. METHOD: The distal stump of the transected peroneal nerve was sutured to the side of the uninjured sural nerve. After 36 weeks, sprouting of sensory axons into the end-to-side coapted nerve was assessed by the electrophysiologic measurements of compound action potential and by counting the myelinated axons. The neurons in the dorsal root ganglia (DRG) L5 whose axons sprouted into the end-to-side coapted nerve were retrogradely labelled by the fluorescent dye Fluorogold. The expression of trkA in sprouting DRG neurons was investigated by immunohistochemistry. FINDINGS: Predominantly thin myelinated axons were found in the end-to-side coapted peroneal nerve. Their mean conduction velocity (CV) was between the average CVs of the Adelta and Abeta fibres in the normal sural nerves. About 90% of the sprouting DRG neurons were small and medium sized, and about 10% were large. About 85% of sprouting DRG neurons was immunoreactive to trkA, but the rest were not. CONCLUSIONS: Mostly the high-threshold sensory afferents sprouted into the end-to-side coapted nerve, which resembles the collateral sprouting of sensory axons in the skin. However, our results suggest that also some low-threshold mechanoreceptors can sprout after the end-to-side nerve repair.

Articaine is more effective than lidocaine or mepivacaine in rat sensory nerve conduction block in vitro.

The reasons for the relatively high failure rate after inferior alveolar nerve block in dentistry are not fully understood. Therefore, the effectiveness of different anesthetic solutions (2% and 4% lidocaine, 3% mepivacine, 2% and 4% articaine) in depressing the compound action potential amplitude of the sensory fibers in the rat sural nerve was examined under strictly controlled conditions in vitro. After application of an anesthetic solution and stimulation of the nerve with a supramaximal electrical stimulus, a complete disappearance of the compound action potential of the C fibers, but not of the A fibers, was observed in all the experimental groups. Both 2% and 4% articaine more effectively depressed the compound action potential of the A fibers than did other anesthetic solutions. These results are discussed in the light of recent clinical reports finding no differences in the effectiveness between 4% articaine and 2% lidocaine regarding the inferior alveolar nerve block.

Effect of generalized sympathetic activation by cold pressor test on cerebral hemodynamics in diabetics with autonomic dysfunction.

BACKGROUND: We examined the effects of the cold pressor test on the cerebral circulation in diabetics with autonomic dysfunction without orthostatic hypotension using transcranial Doppler. METHODS: Twenty diabetics with autonomic dysfunction and 19 age-matched healthy controls participated in the study. The mean arterial blood velocity was measured in the middle cerebral artery during the cold pressor test together with the mean arterial blood pressure. RESULTS: The mean arterial blood velocity significantly (p < 0.01) increased during the 1st, 2nd, and 3rd min of the cold pressor test by 10.6, 14.1, and 13.4%, respectively, in the control subjects and by 5.8, 7.2, and 6.8%, respectively, in the diabetics. Simultaneously, the mean arterial blood pressure significantly (p < 0.01) increased by 12, 26, and 23%, respectively, in the controls and by 9.4, 12.4 and 12.9%, respectively, in the diabetics. The increases in the mean arterial velocity as well as in the mean arterial blood pressure were significantly higher in the controls than in the diabetics (p < 0.01). The change in the mean arterial blood pressure related significantly to the change in the mean arterial blood velocity both in the controls (p < 0.01, r = 0.76) and in the diabetics (p < 0.01; r = 0.59). The slope of the regression line was significantly steeper in the controls (b = 0.42, SE = 0.05) as compared with the diabetics with autonomic dysfunction (b = 0.27, SE = 0.05; p = 0.02). Moreover, also the relative increase in the cerebrovascular resistance index was higher in the controls than in the diabetics (p < 0.05). CONCLUSION: These findings in the diabetics with autonomic neuropathy, but without orthostatic hypotension, suggest a failure in the cerebral autoregulation due to impaired cerebrovascular neurogenic control.

Coupling between visual evoked cerebral blood flow velocity responses and visual evoked potentials in migraneurs.

Neurovascular coupling may be altered in migraneurs. Therefore, visual evoked potentials (VEP) and visually evoked cerebral blood flow velocity responses (VEFR) were simultaneously recorded in 30 healthy controls and 30 migraneurs interictally using a checkerboard stimulus with visual contrasts of 1%, 10% and 100%. The VEFR were measured in the posterior cerebral artery using transcranial Doppler and VEP were recorded from occipital leads. We found an increase in VEFR and VEP in both the healthy and migraneur groups (P < 0.01). VEFR were significantly higher in migraneurs (P < 0.01), while VEP did not significantly differ between the groups (P > 0.05). Regression showed a significant association between VEP and VEFR in both healthy controls (r = 0.66, P < 0.01) and migraneurs (r = 0.63, P < 0.01). The regression coefficient of migraneurs (b = 0.88, SE = 0.08) was significantly higher than that of healthy controls (b = 0.55, SE = 0.07) (P = 0.04). We conclude that neurovascular coupling is increased in migraneurs interictally.

Nerve fibre composition of the palmar cutaneous branch of the median nerve and clinical implications.

Fifteen fresh human cadaver hands were dissected, using x2.8 loupe magnification, to study the subcutaneous innervation at the site of the incision (in the line with the radial border of the ring finger) for standard open carpal tunnel decompression. Subcutaneous nerve branches were detected and traced proximally to determine their origin. Morphometric analysis of nerve cross sections from the site of the incision and from the main nerve trunk proximal to cutaneous arborisation was performed using light and transmission electron microscopy and a computer-based image analysis system. At the site of the incision, the ulnar sub-branch (US) of the palmar cutaneous branch of the median nerve (PCBMN), which innervates the skin over the hypothenar eminence, was found in 10 of 15 cases. Branches from the ulnar side were not detected. The main trunk of PCBMN consisted on average of 1000 (SD 229) myelinated axons arranged in 1-4 fascicles. In the US of the PCBMN there were on average 620 (SD 220) myelinated axons, 80% of them smaller than 40 microm(2) i.e. thin myelinated axons, and on average 2037 (SD 1106) unmyelinated axons, arranged in 1-3 fascicles. The ratio of the number of myelinated axons in the US and the main trunk of the PCBMN was on average 63% (SD 19%). Frequency distribution of cross-sectional areas of myelinated axons shows no significant difference between the US and the main nerve trunk of the PCBMN. The importance of incision trauma to subcutaneous innervation of palmar triangle is emphasised and possible mechanisms of scar discomfort are discussed.

Sex-related difference in collateral sprouting of nociceptive axons after peripheral nerve injury in the rat.

Possible sex-related differences in the extent of collateral sprouting of noninjured nociceptive axons after peripheral nerve injury were examined. In the first experiment, peroneal, tibial, and saphenous nerves were transected and ligated in female and male rats. Eight weeks after nerve injury, skin pinch tests revealed that the nociceptive area of the noninjured sural nerve in the instep skin expanded faster in females; the final result was a 30% larger increase in females than in males. In the second experiment, the end-to-side nerve anastomosis was used as a model for axon sprouting. In addition to the previous procedure, the end of an excised peroneal nerve segment was sutured to the side of the intact sural nerve. Eight weeks later, collateral sprouting of nociceptive axons into the anastomosed peroneal nerve segment was assessed by the nerve pinch test and axon counting. There was no significant difference with respect to the percentages of male and female rats with a positive nerve pinch test. The number of myelinated axons in the anastomosed nerve segment was significantly larger in female (456 +/- 217) than in male (202 +/- 150) rats, but the numbers of unmyelinated axons were not significantly different. In normal sural nerves, the numbers of either all myelinated axons or thin myelinated axons did not significantly differ between the two sexes. Therefore, the more extensive collateral axon sprouting observed in female than in male rats is probably due to the higher sprouting capacity of thin myelinated sensory axons in females.

Interneuronal signalling is involved in induction of collateral sprouting of nociceptive axons.

Collateral sprouting of cutaneous nociceptive axons into the adjacent denervated skin critically depends on the nerve growth factor, presumably originating from the degenerated neural pathways and denervated skin. We hypothesised that the degenerated neural pathways are necessary, but not sufficient, to induce collateral sprouting of nociceptive axons, and, in addition, that the interaction between the injured and non-injured neurones within a dorsal root ganglion can trigger sprouting of nociceptive axons also in the absence of the denervated skin. End-to-side nerve anastomosis, made in female Wistar rats by suturing the end of an excised peroneal nerve segment to the side of the intact sural nerve, was used as a model for sprouting which allowed us to study the putative induction mechanisms separately. If the nerves adjacent to the sural nerve were transected concomitantly with the coaptation of the end-to-side anastomosis, robust nociceptive axon sprouting into the anastomosed nerve segment was observed by the nerve pinch test and counting of myelinated axons. Collateral sprouting did not occur, however, either if the cells in the anastomosed nerve segment were killed by freezing and thawing, or if the adjacent nerves had not been injured. However, if the ipsilateral dorsal cutaneous nerves, having their neurones in the same dorsal root ganglia as the sural nerve, were transected, but no other nerves were injured, then the sural nerve axons sprouted in abundance through the anastomosis even in the absence of denervated skin around the sural nerve terminals. From these results we suggest that cells (probably proliferating Schwann cells) in the degenerated neural pathways are necessary but not sufficient to induce collateral sprouting of nociceptive axons, and that interactions between the injured and non-injured neurones within the dorsal root ganglion (i.e. direct or indirect interneuronal signalling) are important in this regard.

Sensitivity of sensory axons to lidocaine nerve block in rats.

The aim of the present study was to test the sensitivity of different classes of sensory axons to lidocaine 2 and 4% nerve block. The basic approach was to examine changes in compound action potential (CAP) of A and C axons of the rat sural nerve induced by 2 or 4% lidocaine nerve block in vitro. CAP in control sural nerves (n = 6 for each experimental group) before nerve block was induced, consisted of the early component (A axons: 0.3 +/- 0.02 ms) and the late component (C axons: 12.2 +/- 1.14 ms) with peak voltage amplitudes 4.4 +/- 1.4 mV and 0.04 +/- 0.02 mV, respectively. Lidocaine 2% nerve block completely abolished the amplitude of CAP of C axons and depressed the amplitude of CAP of A axons to about 20 % of control level. Doubled concentration of lidocaine significantly decreased time taken to develop maximal depression of CAP and significantly increased excitation threshold of sensory A axons, but not of sensory C axons. However, 4% lidocaine did not affect the maximal depression of CAP of sensory A axons. These results support the view, that C axons are more sensitive to lidocaine nerve block than A axons. In addition, our results suggest a population of sensory A axons which is non-sensitive to 2% and 4% lidocaine.

Schwann cell dependence of regenerating rat sensory neurons is inversely related to the quality of axon growth substratum.

It is still controversial to what extent elongation of regenerating sensory axons depends on proliferating Schwann cells (SCs) in an injured peripheral nerve. We hypothesized that such regeneration was independent of SC support early after nerve injury, but later became SC-dependent. The sural nerve in rats was crushed, and freezing destroyed cells but not their basal laminae (BL) in the distal nerve segment. Sensory axon elongation was assessed by the nerve pinch test and their abundance was examined immunohistochemically. Sensory axons regenerated fairly rapidly during the first week even if SC migration was prevented. Thereafter, they ceased to elongate and withdrew until their terminals contacted the SCs migrating from the proximal nerve segment. Intrinsic neuronal capacity for growth without cell support, however, had not been lost. Rather, progressive degradation of the former SC BL and loss of laminin in the acellular segment arrested axon growth. Further elongation occurred only when SC migration was possible, corroborating our hypothesis. Sensory neurons continued to elongate and maintain their axons in spite of deteriorating growth substratum if, prior to injury the axons had been allowed to sprout into the denervated skin. Previous sprouting exposed the sensory neurons to high levels of NGF.

Reversible transitions between synchronization states of the cardiorespiratory system.

Phase synchronization between cardiac and respiratory oscillations is investigated during anesthesia in rats. Synchrograms and time evolution of synchronization indices are used to show that the system passes reversibly through a sequence of different phase-synchronized states as the anesthesia level changes, indicating that it can undergo phase transitionlike phenomena. It appears that the synchronization state may be used to characterize the depth of anesthesia.

Sensitivity of peripheral nerve fibres to sodium pentobarbital anaesthesia in rat.

The sensitivity of different classes of peripheral nerve fibres to anaesthesia with sodium pentobarbital in rat was tested. The basic approach was to examine changes in compound action potential (CAP) in a rat sural nerve induced by sodium pentobarbital. Rats were either sacrificed by cervical dislocation (control) or anaesthetized with sodium pentobarbital (100 mg/kg, i.p.), and a 30 mm long sural nerve segment excised and placed on electrodes in a thermostatically controlled recording chamber. CAPs were evoked by electrically stimulating the sural nerve segment with supra-threshold stimuli. CAP in control sural nerves consisted of the early component (A axons: 32.73 +/- 2.91 m/s) and the late component (C axons: 0.92 +/- 0.05 m/s) with peak voltage amplitudes 4.9 +/- 1.0 mV and 0.1 +/- 0.03 mV, respectively. Anaesthesia with sodium pentobarbital had no effect on CAP latency. However, the amplitude of CAP of both A and C axons was reduced by approximately 40% and 50%, respectively. The depressant effect of pentobarbital on CAPs was statistically significant for both groups of axons (p<0.01). Non-selective sensitivity of A and C axons to pentobarbital suggests even distribution of receptors for GABA in these two populations of axons in the rat peripheral nerve.

The contribution of lumbar sympathetic neurones activity to rat's skin blood flow oscillations.

Skin blood flow on the rat's paws using laser Doppler flowmeter, electrical activity of the heart (ECG) and respiration were measured simultaneously. The signals were recorded for 20 minutes, both before and after denervation, at core temperature 37 degrees C and 38.5 degrees C, that was maintained constant during the recordings. Spinal nerve fibres, at the level L3-L4, were transected. Experiments were performed on 15 adult Wistar rats under general anaesthesia. The oscillations in the measured signals were analysed in the time-frequency domain using wavelet transform. On the frequency region from 0.7 Hz to 5 Hz two characteristic peaks were observed in the skin blood flow spectrum. They correspond to the main peaks in the spectra of the ECG (around 3.3 Hz) and respiration (around 1.3 Hz). Several additional peaks were observed in the low frequency region, from 0.01 to 0.7 Hz, in all measured signals. In this frequency region the relative energy contribution of the blood flow oscillations decreased after denervation only in the denervated left hind paw. This difference was not statistically significant at 37 degrees C (p=0.098, Kruskal-Wallis test) but became statistically significant at 38.5 degrees C (p=0.017). Relative energy contribution of the low frequency region, from 0.01 to 0.7 Hz, decreased 2.5-fold in the blood flow of the denervated paw. Within this region the relative energy contribution decreased significantly in two intervals, from 0.01 to 0.08 Hz and from 0.08 to 0.2 Hz (p=0.023). In the higher frequency region, from 0.7 to 5 Hz, o statistically significant differences were obtained in any paws when compared before and after denervation at the same core temperature. We conclude that the activity of lumbar sympathetic neurones contributes to low frequency skin blood flow oscillations.

The contribution of lumbar sympathetic neurones activity to rat's skin blood flow oscillations.

Skin blood flow on the rat's paws using laser Doppler flowmeter, electrical activity of the heart (ECG) and respiration were measured simultaneously. The signals were recorded for 20 minutes, both before and after denervation, at core temperature 37°C and 38.5°C, that was maintained constant during the recordings. Spinal nerve fibres, at the level L3-L4, were transected. Experiments were performed on 15 adult Wistar rats under general anaesthesia. The oscillations in the measured signals were analysed in the time-frequency domain using wavelet transform. On the frequency region from 0.7Hz to 5Hz two characteristic peaks were observed in the skin blood flow spectrum. They correspond to the main peaks in the spectra of the ECG (around 3.3Hz) and respiration (around 1.3Hz). Several additional peaks were observed in the low frequency region, from 0.01 to 0.7 Hz, in all measured signals. In this frequency region the relative energy contribution of the blood flow oscillations decreased after denervation only in the denervated left hind paw. This difference was not statistically significant at 37°C (p=0.098, Kruskal-Wallis test) but became statistically significant at 38.5°C (p=0.017). Relative energy contribution of the low frequency region, from 0.01 to 0.7Hz, decreased 2.5-fold in the blood flow of the denervated paw. Within this region the relative energy contribution decreased significantly in two intervals, from 0.01 to 0.08Hz and from 0.08 to 0.2Hz (p=0.023). In the higher frequency region, from 0.7 to 5Hz, o statistically significant differences were obtained in any paws when compared before and after denervation at the same core temperature. We conclude that the activity of lumbar sympathetic neurones contributes to low frequency skin blood flow oscillations.

Recovery of cutaneous pain sensitivity after end-to-side nerve repair in the rat.

OBJECT: The hypothesis that collaterally sprouting axons from an uninjured donor nerve may provide recovery of pain sensitivity in the skin after end-to-side nerve repair was investigated in rats. In addition, the effect of this technique on the donor nerve was examined. METHODS: The distal stump of the transected peroneal nerve was sutured end to side to the intact sural nerve. No epineurial window or perineurial slit was made in the sural nerve at the site of coaptation. Other nerves in the leg were transected and ligated. Eighteen weeks later, the sural nerve was transected at a site distal from the coaptation site. The residual pain sensitivity in the peroneal innervation field in the instep was documented using the skin pinch test in three of 11 animals. The area of sensitivity encompassed 19 to 40% of the maximum nociceptive innervation area of the normal peroneal nerve. The nerve pinch test revealed functional sensory axons in all communicating peroneal nerves, in which 277+/-119 myelinated axons (mean +/- standard deviation) were found by histological investigation. CONCLUSIONS: The authors conclude that at least partial recovery of sensory function due to collateral sprouting of axons after end-to-side nerve repair is possible in principle. However, the presence of functional sensory axons in the peroneal nerve stumps did not guarantee the recovery of skin sensitivity to pain in all animals. No functional or morphological evidence of an untoward effect of collateral sprouting into the end-to-side communicating nerve was detected in the axons of the donor nerve itself.

Prior collateral sprouting enhances elongation rate of sensory axons regenerating through acellular distal segment of a crushed peripheral nerve.

Regenerating axons in crushed peripheral nerves grow through their distal nerve segments even in the absence of Schwann cell support, but their elongation rate is reduced by 30%. We examined whether prior exposure of sensory neurons to trophic factors achieved either by collateral sprouting or regeneration after conditioning lesion could enhance subsequent regeneration of their axons after crush, and compensate for loss of cell support. Collateral sprouting of the peroneal cutaneous sensory axons in the rat was evoked by transection of adjacent peripheral nerves in the hind leg. The segment of the peroneal nerve distal to the crush was made acellular by repeated freezing. Sensory axon elongation rate during regeneration was measured by the nerve pinch test. Prior axonal sprouting for two weeks increased the elongation rate of sensory axons through the acellular distal nerve segment back to normal value observed in control crushed nerves. The number of axons in the acellular distal segment at a fixed distance from the crush site was about 50% greater in sprouting than in control non-sprouting nerves. However, prior sprouting caused no further increase of axon elongation rate in control crushed nerves. Prior collateral sprouting, therefore, could in some respect compensate for loss of cell support in the distal nerve segment after crush lesion. This suggests that loss of cell-produced trophic factors is probably responsible for slower elongation rate through the acellular distal nerve segment. Surprisingly, prior conditioning lesion caused no enhancement of elongation rate of the sensory axons regenerating in the absence of cell support.

Failure of inferior alveolar nerve block in endodontics.

Analgesia is essential for successful completion of modern dental procedures. Standard inferior alveolar nerve block (IANB) is the primary method used to achieve mandibular analgesia. Difficulty experienced in obtaining satisfactory analgesia after IANB, especially of an acutely inflamed mandibular molar, remains a common clinical problem. Even when a proper technique is employed, clinical studies show that IANB fails in approximately 30% to 45% of cases. The reasons for failure are not fully understood. Anatomical considerations and abnormal physiological responses in the presence of inflammation as explanations for IANB failure are discussed in this paper.