Motor nerve graft is better than sensory nerve graft for survival and regeneration of motoneurons after spinal root avulsion in adult rats

Objective. It aimed to explore the application of the microscopic hyperspectral technique in motor and sensory nerve classification. Methods. The self-developed microscopic hyperspectral acquisition system was applied to collect the data of anterior and posterior spinal cord sections of white rabbits. The joint correction algorithm was employed to preprocess the collected data, such as noise reduction. On the basis of pure linear light source index, a new pixel purification algorithm based on cross contrast was proposed to extract more regions of interest, which was used for feature extraction of motor and sensory nerves. Besides, the ML algorithm was employed to classify motor and sensory nerves based on feature extraction results. Results. The joint correction algorithm was adopted to preprocess the data collected by the microscopic hyperspectral technique, so as to eliminate the influence of the incident light source and the system and improve the classification accuracy. The axon and myelin spectrum curves of the two kinds of nerves in the stained specimens had the same trend, but the values of all kinds of spectrum of sensory nerves were higher than those of motor nerves. However, the myelin sheath spectrum curves of motor nerves in the unstained specimens were greatly different from the curves of sensory nerves. The axon spectrum curves had the same trend, but the axon spectrum values of sensory nerves were higher than those of motor nerves. The ML algorithm had high accuracy and fast speed in motor and sensory nerve classification, and the classification effect of stained specimens was better than that of unstained specimens. Conclusion. The microscopic hyperspectral technique had high feasibility in sensory and motor nerve classification and was worthy of further research and promotion.

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Bupivacaine Preferentially Blocks Ventral Root Axons in Rats

Anesthesiology ◽

10.1097/00000542-199701000-00021 ◽

1997 ◽

Vol 86 (1) ◽

pp. 172-180 ◽

Cited By ~ 6

Author(s):

Friederike B. Dietz ◽

Richard A. Jaffe

Keyword(s):

Motor Nerve ◽

Conduction Block ◽

Sensory Nerve ◽

Differential Susceptibility ◽

Nerve Fibers ◽

Ventral Root ◽

Differential Sensitivity ◽

Male Rats ◽

Spinal Root

Background Clinically, bupivacaine can provide excellent sensory anesthesia with minimal impairment of motor function. However, the mechanisms by which local anesthetics produce differential sensory-motor nerve block is still unknown. The primary site of action for spinal and epidural anesthetics is thought to be the intradural segment of the spinal root. To determine the differential susceptibility of single motor and sensory nerve fibers to local anesthetic conduction block, bupivacaine effects on individual dorsal root (DR) and ventral root (VR) axons were studied. Methods Lumbar DRs and VRs were excised from anesthetized adult male rats. Single-fiber dissection and recording techniques were used to isolate activity in individual axons. Supramaximal constant-voltage stimuli at 0.3 Hz were delivered to the root. During in vitro perfusion, each root was exposed to increasing concentrations of bupivacaine, and the minimum blocking concentration (C(m)) and the concentration that increased conduction latency by 50% (latency EC50) were measured. Results Ventral root axons were significantly more sensitive to the steady-state conduction blocking effects of bupivacaine than were either myelinated or unmyelinated DR axons (DR-C(m), 32.4 microM; VR-C(m), 13.8 microM; P < 0.0001). In addition, VR axons were more susceptible to the latency-increasing effects of bupivacaine than were DR axons (DR-EC50 = 20.7 microM; VR-EC50 = 8.5 microM; P < 0.0001). Within axon groups, differential sensitivity as a function of conduction velocity (axon diameter), or length of nerve exposed to the anesthetic could not be demonstrated. Conclusions In contrast to clinical expectations, low concentrations of bupivacaine preferentially block motor (VR) axons in the rat.

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