Miniature in vivo MEMS-based line-scanned dual-axis confocal microscope for point-of-care pathology.

There is a need for miniature optical-sectioning microscopes to enable in vivo interrogation of tissues as a real-time and noninvasive alternative to gold-standard histopathology. Such devices could have a transformative impact for the early detection of cancer as well as for guiding tumor-resection procedures. Miniature confocal microscopes have been developed by various researchers and corporations to enable optical sectioning of highly scattering tissues, all of which have necessitated various trade-offs in size, speed, depth selectivity, field of view, resolution, image contrast, and sensitivity. In this study, a miniature line-scanned (LS) dual-axis confocal (DAC) microscope, with a 12-mm diameter distal tip, has been developed for clinical point-of-care pathology. The dual-axis architecture has demonstrated an advantage over the conventional single-axis confocal configuration for reducing background noise from out-of-focus and multiply scattered light. The use of line scanning enables fast frame rates (16 frames/sec is demonstrated here, but faster rates are possible), which mitigates motion artifacts of a hand-held device during clinical use. We have developed a method to actively align the illumination and collection beams in a DAC microscope through the use of a pair of rotatable alignment mirrors. Incorporation of a custom objective lens, with a small form factor for in vivo clinical use, enables our device to achieve an optical-sectioning thickness and lateral resolution of 2.0 and 1.1 microns respectively. Validation measurements with reflective targets, as well as in vivo and ex vivo images of tissues, demonstrate the clinical potential of this high-speed optical-sectioning microscopy device.

Motor evoked potential studies in Creutzfeldt-Jakob disease.

OBJECTIVES: Motor evoked potentials (MEPs) were recorded in 7 cases of Creutzfeldt-Jakob disease (CJD) to asses the involvement of pyramidal motor pathways in these cases. The diagnosis of CJD was confirmed by autopsy in 5 cases and based on clinical data in two cases. METHODS: Transcranial (MEP-cortex), root magnetic (MEP-root) and electrical stimulation of peripheral nerves (F-wave, direct M-response) were performed. The cortical excitability threshold, F-wave frequency, MEP amplitudes, peripheral motor conduction velocity, standardized distal latencies and central, root, and F-wave conduction times were evaluated. RESULTS: The results of MEP testing were markedly abnormal. Cortical excitability thresholds were elevated, MEP amplitudes were reduced while the conduction function was rather preserved. The features of functional disturbances and/or loss of upper and lower motor neurons were revealed. They correlated with the advancement of key clinical CJD symptoms (progressive dementia, extrapyramidal and cerebellar signs, myoclonic jerks, mutism and typical periodic EEG changes), while motor lesion signs might only be slight or absent. CONCLUSIONS: Conduction slowing, if present, seemed to be secondary to axonal lesion.

Peculiarity of soleus motor potentials evoked by transcranial magnetic stimulation and electrical stimulation of tibial nerve.

OBJECTIVE: To reveal and discuss the peculiarities of soleus muscle in comparison with electrophysiological features of other leg muscles. METHODS: Vastus lateralis (L3), tibialis anterior (L4), extensor digitorum brevis (L5) and soleus (S1) muscles were tested at rest. Transcranial magnetic stimulation (TMS) combined which electrical stimulation of relevant peripheral nerves were applied. Cortically evoked motor potentials (C-MEP), peripheral compound muscle action potential (CMAP) and F-wave were recorded. Estimating F-wave conduction time allowed to calculated the central conduction time (CCT-F) within the cortex-spinal motoneurones segment for each muscle. RESULTS: One could expect that the lower spinal metameric representation of the muscle the longer a corresponding CCT-F. However, a study of 30 healthy subject (60 right and left muscles) reveals a relatively short CCT-F for the soleus muscle. Moreover, the mean amplitude of soleus C-MEP is the lowest, CMAP and F-wave amplitude are the highest and standardised distal motor latency is the longest compared to the analogous parameters for the other muscles. CONCLUSIONS: The reason for these special features can be attributed probably to a different structure and innervation of the soleus (mainly red, slow, tonic muscle) in contrast to the tibialis anterior and extensor digitorum brevis (mainly white, fast, phasic muscle).

[Motor segmental conduction times for extensor digitorum brevis muscle: method and normative values]. / Odcinkowe czasy przewodzenia w drogach ruchowych dla miesnia prostownika palców krótkiego: metoda i wartosci normatywne.

Electrical stimulation of the peroneal nerves (60 nerves) and magnetic stimulation of the roots (L5) and motor cortex were performed on 30 normal controls. The muscle responses and F wave (peripheral stimulation) were recorded from extensor digitorum brevis muscle (60 muscles). The parameters of examined potentials were measured and the central, root, peripheral motor conduction times, were estimated. The normative values were established as well as formulae of linear regression within the observed correlations with height. The method may be used for electrophysiological diagnosis of patients with motor pathway impairment on the different levels.

Cortical excitability threshold for distal limb muscles in transcranial magnetic stimulation. Method--normative values.

Transcranial magnetic stimulation was carried out in 30 healthy subjects, aged 20 to 55 and 156 to 180 cm tall, in whom cortical excitability threshold was determined for musculus (m.) abductor digiti minimi (ADM) and m. extensor digitorum brevis (EDB). The lowest stimulus intensity causing in the muscle a reproducible potential of an amplitude of 0.1 mV was adopted as the threshold value. The intensity of the stimulus was noted as a percentage of maximum stimulator output, defined as 100% (Magstim 200). In the stimulation of cortical areas for ADM, a circular coil (2.0T-530 V/m) was used while the in case of EBD, a double-cone coil (1.4T-660 V/m) was used. The threshold was noted while the muscle was relaxed and during weak voluntary contraction. The application of the double-cone coil allowed us to obtain for foot muscles similar threshold values as for hand muscles with a circular coil. It was confirmed that the threshold declines with voluntary contraction of the muscles under investigation. Normative values were prepared, with the norm, limits of the norm, outlier values and pathological markers being distinguished.

Segmental conduction times in the motor nervous system.

The study was performed in 30 normal subjects (24 females and 6 males) with an age range between 18 and 55 years and a height range between 154 and 188 cm. Electrical stimulation was applied to the peroneal nerve with simultaneous recording of the orthodromic response (MEP-M) and F-wave (MEP-F) from the tibialis anterior (TA) and extensor digitorum brevis muscles (EDB). Magnetic stimulation of the L5 level and cerebral cortex was applied using different coils with simultaneous recording of responses from the right and left TA and EDB muscles. Mean normative values and formulae of linear regression were established within the observed correlations with height for the parameters measured (latencies) and derived parameters (segmental conduction times). A software system was developed which allows the readout of the selected parameter values from the Mystro device, calculation of the derived parameters, and classification of the results according to 95% confidence intervals for the parameters obtained in the group of normal subjects included in the study. This fast and painless investigation, which carries no risk to the patient, should prove useful in the electrophysiological diagnosis of motor pathway function including the entire length.

[Segmental conduction times in motor pathways for the soleus muscle--methodology and normal values]. / Odcinkowe czasy przewodzenia w unerwieniu ruchowym m.soleus--opis metody i wartosci normy.

The study performed in 30 normal subjects (24F, 6M) with age range 18-55 years and height range 154-188 cm. Electrical stimulation was applied to the tibial nerves and direct response M and F-wave was recorded from right and left SOLEUS (60 examinations). Transcranial and paravertebral (S1 level) magnetic stimulation was applied with simultaneous recording of responses from both SOL. A software system was developed which permitted the redout of parameters (latencies and amplitudes) from Mystro device, calculation of the derived parameters (segmental motor conduction times) and classification of results according to 95% confidence intervals for the parameters obtained in the group of normal subjects included in the study. Report form was prepared which on line gave the results of individuals examinations. The fast and painless investigation should prove useful in electrophysiological diagnosis of motor pathway function including the entire length.

[Segmental motor conduction time for abductor of the fifth finger muscle: methods and normative values]. / Odcinkowe czasy przewodzenia w drogach ruchowych dla miesnia odwodziciela palca V reki: metoda i wartosci normatywne.

Electrical stimulation of the ulnar nerves (60 nerves) and magnetic stimulation of the roots (C7) and motor cortex were performed on 30 normal controls. The muscle responses and F wave (peripheral stimulation) were recorded from abductor digiti minimi muscle (60 muscles). The parameters of examined potentials were measured and the central, root, peripheral motor conduction times were estimated. The normative values were established as well as formulae of linear regression within the observed correlations with height. The method may be used for electrophysiological diagnosis of patients with motor pathway impairment at the different levels.

The F-wave in the vastus lateralis M. and the segmental motor conduction times for L2/L4 motoneurons.

The study was performed in 30 normal subjects. Electrical stimulation was applied to the femoral nerves and the muscle evoked potential (CMAP) together with their late components were recorded from the vastus lateralis muscle bilaterally (60 nerves). Features of the late component demonstrating its antidromic nature (F-wave) were proved. Additionally, in each subject transcranial cortical (C) magnetic stimulation and root (Rx) magnetic stimulation at the level of the L3-L4 was applied. The measured latencies of respective motor evoked potentials C-MEP (relaxed muscles), CA-MEP (activated), Rx-MEP as well as the latencies of peripheral CMAP and F-wave allowed the calculation of the derived parameters, i.e. segmental times of motor conduction: central, root and peripheral. The normative values were established. The F-wave measurement also allowed for the calculation of the so-called real central conduction time, which proved to be significantly shorter than the corresponding times previously established for the lower situated L4/S1 motoneurons. This finding suggests usefulness of the method in the precise diagnosis of the lumbosacral spinal enlargement.

[Dermatomal somatosensory evoked potentials from L3, L4, L5 and S1 spinal roots in healthy subjects]. / Dermatomalne somatosensoryczne potencjaly wywolane z korzeni L3, L4, L5, S1 u osób zdrowych.

Dermatomal somatosensory evoked potentials (DSEPs) were recorded in 62 healthy volunteers aged from 15 to 65 years (mean 36.8 +/- 12.9 years) with height from 1.5 to 1.92m (mean 1.69 +/- 0.10m). The aim of the study was to establish normal values for L3, L4, L5 and S1 dermatomes and to introduce this method for the neurophysiological diagnosis of chronic lumbosacral pain and disc disease. The signature areas of dermatomes in both legs separately were stimulated according to the method described by Sedgwick and Katifi (1985). DSEPs were recorded from the scalp electrodes placed at Cz', referred to Fpz. The latencies and amplitudes of consecutive components of DSEPs: N33, P40, N50, P60, N75 and side to side differences were measured and evaluated. Statistical analysis of the results revealed significant positive correlation of DSEPs latencies as a function of height. The correlation of amplitudes with height was less significant. Age, on other hand, showed only negative correlation with amplitudes of later DSEP components. On the basis of the performed analysis the latency of P40 and amplitude of P40-N50 seem to be the best parameters for the evaluation of pathological DSEPs. The range of normal value of latencies for stimulated roots should be calculated from regression equation with the subject's height. As regards amplitude, side to side mean value difference above two standard deviation appears to be more useful.