Segmental spinal sympathetic machinery: Implications for autonomic dysreflexia

From pain to tumor immunity: influence of peripheral sensory neurons in cancer

The nervous and immune systems are the primary sensory interfaces of the body, allowing it to recognize, process, and respond to various stimuli from both the external and internal environment. These systems work in concert through various mechanisms of neuro-immune crosstalk to detect threats, provide defense against pathogens, and maintain or restore homeostasis, but can also contribute to the development of diseases. Among peripheral sensory neurons (PSNs), nociceptive PSNs are of particular interest. They possess a remarkable capability to detect noxious stimuli in the periphery and transmit this information to the brain, resulting in the perception of pain and the activation of adaptive responses. Pain is an early symptom of cancer, often leading to its diagnosis, but it is also a major source of distress for patients as the disease progresses. In this review, we aim to provide an overview of the mechanisms within tumors that are likely to induce cancer pain, exploring a range of factors from etiological elements to cellular and molecular mediators. In addition to transmitting sensory information to the central nervous system, PSNs are also capable, when activated, to produce and release neuropeptides (e.g., CGRP and SP) from their peripheral terminals. These neuropeptides have been shown to modulate immunity in cases of inflammation, infection, and cancer. PSNs, often found within solid tumors, are likely to play a significant role in the tumor microenvironment, potentially influencing both tumor growth and anti-tumor immune responses. In this review, we discuss the current state of knowledge about the degree of sensory innervation in tumors. We also seek to understand whether and how PSNs may influence the tumor growth and associated anti-tumor immunity in different mouse models of cancer. Finally, we discuss the extent to which the tumor is able to influence the development and functions of the PSNs that innervate it.

A Hierarchical Machine Learning Solution for the Non-Invasive Diagnostic of Autonomic Dysreflexia

More than half of patients with high spinal cord injury (SCI) suffer from episodes of autonomic dysreflexia (AD), a condition that can lead to lethal situations, such as cerebral haemorrhage, if not treated correctly. Clinicians assess AD using clinical variables obtained from the patient’s history and physiological variables obtained invasively and non-invasively. This work aims to design a machine learning-based system to assist in the initial diagnosis of AD. For this purpose, 29 patients with SCI participated in a test at Cruces University Hospital in which data were collected using both invasive and non-invasive methods. The system proposed in this article is based on a two-level hierarchical classification to diagnose AD and only uses 35 features extracted from the non-invasive stages of the experiment (clinical and physiological features). The system achieved a 93.10% accuracy with a zero false negative rate for the class of having the disease, an essential condition for treating patients according to medical criteria.

Peripheral neuroimmune interactions: selected review and some clinical implications

Purpose

To provide a brief and focused review on peripheral neuroimmune interactions and their implications for some clinical disorders.

Methods

Narrative review of the literature including of English-language articles published between 1985 and 2021 using PubMed and MEDLINE.

Results

Many studies on experimental models and in vitro indicate that there are close interactions between the neural and immune systems. Processes from sensory afferents and autonomic efferents co-localize with immune cells and interact at discrete anatomical sites forming neuroimmune units. These neuroimmune interactions are bidirectional and mediated by a wide range of soluble factors including neuropeptides, classical neurotransmitters, cytokines, and other molecules that mediate complex cross-talk among nerves and immune cells. Small-diameter sensory afferents express a wide range of receptors that respond directly to tissue damage or pathogen signals and to chemokines, cytokines, or other molecules released from immune cells. Reciprocally, immune cells respond to neurotransmitters released from nociceptive and autonomic fibers. Neuroimmune interactions operate both at peripheral tissues and at the level of the central nervous system. Both centrally and peripherally, glial cells have a major active role in this bidirectional communication.

Conclusions

Peripheral neuroimmune interactions are complex and importantly contribute to the pathophysiology of several disorders, including skin, respiratory, and intestinal inflammatory disorders typically associated with pain and altered barrier function. These interactions may be relevant for persistence of symptoms in disorders associated with intense immune activation.

Quantitative analysis of dysautonomia in patients with autonomic dysreflexia

Autonomic dysreflexia (AD) is a life-threatening condition for individuals with cervical or high-thoracic spinal cord injury (SCI). The profile of autonomic dysfunction in AD using validated clinical autonomic tests has not been described so far, although it could be useful to identify SCI patients at greater risk of developing AD non-invasively. With this objective, 37 SCI patients (27% female) were recruited, and hemodynamic and cardiac parameters were continuously monitored to determine the presence of AD, defined as an increase of systolic blood pressure of 20 mmHg or higher after bladder filling with saline. Then, standard autonomic function testing was performed, including Deep Breathing, Valsalva Manoeuvre and Tilt Table Test. Finally, baroreflex sensitivity (BRS), and spectral analysis of heart rate and blood pressure variability were measured at rest. Catecholamines and vasopressin levels were also measured at supine and upright positions. The severity of SCI was assessed through clinical and radiological examinations. AD was observed in 73.3% of SCI patients, being 63.6% of them asymptomatic during the dysreflexive episode. AD patients displayed a drop in sympathetic outflow, as determined by decreased noradrenalin plasma levels, reduced sympathovagal balance and increased BRS. In line with decreased sympathetic activity, the incidence of neurogenic orthostatic hypotension was higher in AD patients. Our results provide novel evidence regarding the autonomic dysfunction in SCI patients with AD compared to non-AD patients, posing non-invasively measured autonomic parameters as a powerful clinical tool to predict AD in SCI patients.

Autonomic dysreflexia in a case of radiation myelopathy and cisplatin-induced polyneuropathy

INTRODUCTION

While autonomic dysreflexia caused by severe spinal cord lesions can be life-threatening, relevant reports on non-traumatic spinal lesions are rare. Furthermore, modes of innervation of the supraspinal inhibitory pathways at each spinal sympathetic segment remain unknown. Herein, I report the case of a patient with autonomic dysreflexia and radiation myelopathy. The laterality of autonomic dysreflexia was investigated with special reference to the sudomotor function.

CASE PRESENTATION

A 51-year-old man with a history of epipharynx carcinoma, radiotherapy, and cisplatin chemotherapy was referred for the evaluation of autonomic function. He was ambulant but displayed spastic tetraparesis, areflexia of the extremities, sensory disturbance below C4 dermatome, dysuria, and impotence. Spinal magnetic resonance imaging demonstrated a cervical lesion involving the lateral portion of C2-C5, bilaterally. The thermal sweating test showed that sweating was lower on the left side of the face and neck, left shoulder, and arm than the corresponding parts on the right side. The rest of the body was anhidrotic. Sweating due to autonomic dysreflexia was symmetric, but more abundant on the left side of the face. Acetylcholine-induced sweating was markedly reduced on the left leg.

DISCUSSION

This might be the first documentation of autonomic dysreflexia observed in a patient with radiation myelopathy. The present observations suggested that the supraspinal inhibitory pathway to spinal preganglionic neurons may descend on the same side as thermal sudomotor facilitatory pathways at the cervical level. Furthermore, autonomic dysreflexia was more prominent in the standing position suggesting that the pressure stimulus might enhance autonomic dysreflexia.

Circadian and state-dependent core body temperature in people with spinal cord injury

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

To analyze the circadian rhythm and state-dependent modulation of core body temperature (Tcore) in individuals with spinal cord injury (SCI) under controlled environmental conditions.

SETTING

Institute of the Neurological Sciences of Bologna, Italy.

METHODS

We assessed 48-h rectal Tcore and sleep-wake cycle by means of video-polygraphic recording in five cervical SCI (cSCI), seven thoracic SCI (tSCI), and seven healthy controls under controlled environmental conditions.

RESULTS

cSCI showed higher night-time Tcore values with reduced nocturnal decrease, higher MESOR and earlier acrophase compared with tSCI and controls (p < 0.05 in all comparisons). The mean Tcore values during wake and non-rapid eye movement (NREM) and rapid eye movement (REM) sleep stages were higher in cSCI compared with tSCI and controls (p < 0.05). Tcore variability throughout the 24 h differed significantly between cSCI, tSCI, and controls.

CONCLUSIONS

cSCI had higher Tcore values without physiological night-time fall compared with controls and tSCI, and a disrupted Tcore circadian rhythm. Furthermore, SCI individuals did not display the physiological state-dependent Tcore modulation. The disconnection of the sympathetic nervous system from its central control caused by the SCI could affect thermoregulation including Tcore modulation during sleep. It is also possible that the reduced representation of deep sleep in people with SCI impairs such ability. Further studies are necessary to evaluate whether improvement of sleep could ameliorate thermoregulation and vice versa.