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Spinal Cord and Reflexes
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
Lamina VII of the spinal cord contains the intermediolateral nucleus (Figure 11.2), which extends from vertebral levels T1 to L2, and harbors the autonomic motor neurons of the entire sympathetic innervation of the body. In addition, the various laminae contain propriospinal neurons that transmit signals between segments of the spinal cord. The axons of these neurons form propriospinal tracts that could be ascending, descending, crossed, or uncrossed. Propriospinal neurons may receive strong peripheral input but generally little supraspinal input. The C3-C4 propriospinal system is a special descending system discussed in Section 12.2.5.5.
Neural Regulation
Published in Stephen W. Carmichael, Susan L. Stoddard, The Adrenal Medulla 1986 - 1988, 2017
Stephen W. Carmichael, Susan L. Stoddard
Appel and Eide (1988) extended their previous investigations to identify separate populations of rat preganglionic sympathetic neurons in the intermediolateral cell column of segments T-l to T-4 that innervated either the cervical sympathetic trunk or the adrenal medulla. Neurons to the adrenal medulla were located most laterally in the intermediolateral nucleus. The efferent projections of identified neurons were target-specific, with no neurons identified as innervating both the cervical sympathetic chain and the adrenal medulla. Both populations of neurons were apposed by varicosities immunoreactive for either serotonin or somatostatin. In contrast, oxytocin-immunoreactive varicosities were found only in apposition to preganglionic neurons of the cervical sympathetic trunk. These data provide anatomic evidence of the selective control of different components of the sympathetic nervous system by higher centers.
The Acute Stress Response
Published in Rolland S. Parker, Concussive Brain Trauma, 2016
The PVN influences neuroendocrine behavior and autonomic output. The descending path descends laterally through the hypothalamus and the brainstem. These pathways are distinct from those descending to the posterior pituitary. Axons enter the median forebrain bundle, leave the bundle, and run in the dorsolateral tegmentum in the midbrain, the pons, and the medulla. The descending autonomic pathway synapses on brainstem parasympathetic nuclei such as the dorsal motor nucleus of the vagus and spinal sympathetic neurons in the intermediolateral nucleus of the thoracic and lumbar segments, and also on the spinal parasympathetic neurons in the sacral cord. Other hypothalamic sites contribute axons to the descending visceromotor pathways (details not included). Hematopoiesis (blood forming system) is under sympathetic neural control, directed at bone marrow via adrenergic receptors (Maestroni, 1996).
Chameleons, red herrings, and false localizing signs in neurocritical care
Published in British Journal of Neurosurgery, 2022
Boyi Li, Tolga Sursal, Christian Bowers, Chad Cole, Chirag Gandhi, Meic Schmidt, Stephan Mayer, Fawaz Al-Mufti
Cervical disc herniation (CDH) typically results in ipsilateral neck and arm pain corresponding to the level of the lesion.73 However, false localizing CDH can present with contralaterally radiating neck pain and contralateral upper and lower extremity pain. Diagnosis can be confirmed on MRI. It is hypothesized that this FLS results from cord compression of the lateral spinothalamic tract.73 The symptoms can be completely resolved by surgical discectomy and fusion, further confirming the false localizing nature of the condition.73 CDH as a FLS can also present as hemifacial hyperhidrosis with no facial flushing, anisocoria or blepharoptosis, compensating for anhidrosis/hypohydrosis on the ipsilateral side below the lesion.74 Useful diagnostic tools include the Minor test, quantitative sudomotor function tests, and microneurography of sudomotor nerve activity.74 Tests showing no intramedullary signal abnormalities on MRI suggest that the pathophysiology may be impairment of premotor neuron from the hypothalamus to the intermediolateral nucleus by the disc herniation.74 The ipsilateral anhidrosis or hypohydrosis can directly be attributed to the disc herniation myelopathy.74 Of note, crossed hypohydrosis can occur ipisilateral but above the hyperhidrosis.74 Thus, when patients present with hemihydrosis, the Minor test should be done to determine the anhidrotic and hyperhidrotic areas, and thermography to determine the localization of the potential CDH to be investigated further.74
Estrogen – serotonin interaction and its implication on insulin resistance
Published in Alexandria Journal of Medicine, 2019
It seems direct actions of E2 on MC4R expressing neurons are observed in PVH, as single-minded-1 (SIM-1) neurons expressed the abundant level of ERα [62]. In fact, deletion of ERα from SIM-1 neurons induced obesity [63]. However, another study confirmed that disruptions of MC4R did not influence the effects of E2 on food intake and energy expenditure [62]. Activation of PVH area by E2 mediates peripheral sympathetic activity, probably directly through MC4R expressing neurons or indirectly through POMC and NPY/AgRP neurons [64–66]. As POMC neurons projected its axons to sympathetic and parasympathetic preganglionic neurons in intermediolateral nucleus (IML) and dorsal motor vagal nucleus (DMV), respectively, E2 possibly at the same time increases peripheral insulin sensitivity through sympathetic pathways and decreases insulin secretion through parasympathetic pathways [67].
Restless legs syndrome related to hemorrhage of a thoracic spinal cord cavernoma
Published in The Journal of Spinal Cord Medicine, 2018
Malik Hamdaoui, Elisabeth Ruppert, Henri Comtet, Ulker Kilic-Huck, Valérie Wolff, Marc Bataillard, Patrice Bourgin
How can a thoracic spinal cord lesion at T9-T10 impair pathophysiological pathways of RLS? We hypothesize a possible implication of the dopaminergic diencephalospinal pathway13 involving the dopaminergic neurons of the hypothalamic A11 area. These diencephalic neurons seem to have inhibitory actions and projections to multiple targets in the brain and throughout the spinal cord such as the neocortex, the serotoninergic dorsal raphe nucleus, the sympathetic preganglionic neurons of the intermediolateral nucleus, the sensory dorsal horn of the spinal cord and interneurons. The interruption of such projections at the level of the thoracic spinal cord could contribute to both the sensitive symptoms of RLS and the motor phenomenon occurring during PLMS.12,13 However, this is hypothetical, as the exact neural pathway remains poorly understood. The study of RLS associated with focal lesions may represent an original approach to improving our understanding of RLS pathophysiology.