Laterality of Skin Temperature and Magnetic Resonance Imaging in Patients with Wallenberg Syndrome

Background: Recently, lateral differences in body surface temperature (BST) have been reported as a symptom of Wallenberg syndrome (WS), resulting from disturbances in the sympathetic nerve pathway. This study aimed to investigate the relationship between the laterality of BST and brain magnetic resonance imaging (MRI) findings in 12 patients with WS.Methods: BST was measured using an infrared thermal camera at 7±3 days and 90±30 days after symptom onset. The MRI findings were categorized as rostral, middle, and caudal medulla rostrocaudally and typical, ventral, large, dorsal, and lateral types in the horizontal direction.Results: MRI revealed medullary lesions on the right in five patients and on the left in seven patients. Two patients without lateralized BST had lateral caudal medullary infarction, and one patient had a dorsal middle medullary infarction. One patient with lateralized BST had a rostral medullary infarction and the other had a typical or large middle medulla infarction. Lateralized BST in patients with WS may disturb the sympathetic nervous system pathway that descends from the rostral ventrolateral medulla oblongata. Deficits in sweating and skin blood flow may cause BST laterality.Conclusion: This study showed that lateralized BST in patients with WS may be associated with disturbances in the sympathetic nervous pathway descending from the rostral ventrolateral medulla. These results support the assumption that autonomic dysfunction may be related to abnormal sensory symptoms in patients with WS.

Autonomic Nervous System

The autonomic nervous system is involved in many important unconscious body functions. It is critical for maintaining the internal environment in response to changes in the external environment. The autonomic nervous system consists of peripheral components (sympathetic and parasympathetic nerves and ganglia) and central components (ventrolateral medulla, nucleus ambiguus, nucleus of the solitary tract, periaqueductal gray, anterior cingulate gyrus, insular cortex, amygdala, and hypothalamus). This chapter briefly reviews the anatomy and functional components of the autonomic nervous system and several anatomical clinical correlations.

Brainstem and Cranial Nerves: Longitudinal Pathways of the Brainstem

This chapter reviews pathways that are not at a single level of the brainstem but rather involve multiple areas with supratentorial input. The chapter highlights autonomic pathways, the reticular formation and chemically defined groups, and coordination of eye movements. Sympathetic fibers travel from the hypothalamus to the intermediolateral column in the spinal cord through the lateral brainstem. Patients with a unilateral lesion of the lateral brainstem may have ipsilateral Horner syndrome. The ventrolateral medulla, also a sympathetic region of the brainstem, projects to the spinal cord and is involved in the innervation of blood vessels in the limbs.

The Carotid Body Detects Circulating Tumor Necrosis Factor-Alpha to Activate a Sympathetic Anti-Inflammatory Reflex

Recent evidence has suggested that the carotid bodies might act as immunological sensors, detecting pro-inflammatory mediators and signalling to the central nervous system, which, in turn, orchestrates autonomic responses. Here, we demonstrated that the TNF-α receptor type I is expressed in the carotid bodies of rats. The systemic administration of TNF-α increased carotid body afferent discharge and activated glutamatergic neurons in the nucleus tractus solitarius (NTS) that project to the rostral ventrolateral medulla (RVLM), where the majority of pre-sympathetic neurons reside. The activation of these neurons was accompanied by generalized activation of the sympathetic nervous system. Carotid body ablation blunted the TNF-α-induced activation of RVLM-projecting NTS neurons and the increase in splanchnic sympathetic nerve activity. Finally, plasma and spleen levels of cytokines after TNF-α administration were higher in rats subjected to either carotid body ablation or splanchnic sympathetic denervation. Collectively, our findings indicate that the carotid body detects circulating TNF-α to activate a counteracting sympathetic anti-inflammatory mechanism.

Sedentary Conditions Promote Subregionally Specific Changes in Brain-Derived Neurotrophic Factor in the Rostral Ventrolateral Medulla

A sedentary lifestyle is the top preventable cause of death and accounts for substantial socioeconomic costs to society. The rostral ventrolateral medulla regulates blood pressure under normal and pathophysiological states, and demonstrates inactivity-related structural and functional neuroplasticity, which is subregionally specific. The purpose of this study was to examine pro- and mature forms of brain-derived neurotrophic factor (BDNF) and their respective receptors in the male rat rostral ventrolateral medulla (RVLM) and its rostral extension following sedentary vs. active (running wheels) conditions (10–12weeks). We used subregionally specific Western blotting to determine that the mature form of BDNF and its ratio to its pro-form were lower in more caudal subregions of the rostral ventrolateral medulla of sedentary rats but higher in the rostral extension when both were compared to active rats. The full-length form of the tropomyosin receptor kinase B receptor and the non-glycosylated form of the 75 kilodalton neurotrophin receptor were lower in sedentary compared to active rats. The rostrocaudal patterns of expression of the mature form of BDNF and the full-length form of the tropomyosin receptor kinase B receptor were remarkably similar to the subregionally specific patterns of enhanced dendritic branching, neuronal activity, and glutamate-mediated increases in sympathetic nerve activity observed in previous studies performed in sedentary rats. Our studies suggest signaling pathways related to BDNF within subregions of both the rostral ventrolateral medulla and its rostral extension contribute to cardiovascular disease and premature death related to a sedentary lifestyle.