Electromedicine
Mark V. Boswell, B. Eliot Cole in Weiner's Pain Management, 2005
The mechanism involved in nociceptive pain (Russo, 2001) starts once the noxious stimuli, for example, injury to the skin, has occurred. The nociceptors Aδ and C nerve fibers) pick up the signal, and afferent impulses are relayed to the CNS. The primary afferents synapse in the dorsal horn onto second-order neurons in the substantia gelatinosa of the spinal cord. This is followed by either a synapse via a third-order neuron to the somatosensory cortex or via second-order neurons to the thalamus by the contralateral spinothalamic tract of the spinal cord. Some fibers from the spinothalamic tract travel to the pons and midbrain to synapse on nuclear complexes such as nucleus raphe magnus and the nucleus raphe gigantocellularis (both areas are involved in descending regulation of second-order neurons). Finally, endorphins such as serotonin and epinephrine inhibit noxious stimuli and the continued firing of second-order neurons.
Neuroanatomy of basic cognitive function
Mark J. Ashley, David A. Hovda in Traumatic Brain Injury, 2017
Information flow throughout the CNS is a primary concern for cognitive function. Tactile sensory pathways include those responsible for pain and temperature (lateral spinothalamic tract), those responsible for conscious proprioception and discriminative touch (dorsal column–medial lemniscal pathway), and those responsible for unconscious proprioception (ventral and dorsal spinocerebellar tracts) (Figure 6.1). The lateral spinothalamic tract synapses in the ventral posterior thalamic nucleus and projects via thalamocortical fibers of the posterior limb of the internal capsule to the sensory cortex in the postcentral gyrus of the frontal lobe. Collateral projections from the spinothalamic tract synapse in the brain stem within the reticular formation. The dorsal column–medial lemniscal pathway follows the same course as the lateral spinothalamic tract via the ventral posterior nucleus of the thalamus and posterior limb of the internal capsule on its way to the postcentral gyrus. The anterior spinothalamic tract, which is responsible for perceptions of simple touch, comprises a portion of the dorsal column. The ventral and dorsal spinocerebellar tracts terminate at the level of the cerebellum.
Spinal cord lesions
Ibrahim Natalwala, Ammar Natalwala, E Glucksman in MCQs in Neurology and Neurosurgery for Medical Students, 2022
TRUE Below the level of the Brown-Séquard lesion: corticospinal tract damage causes ipsilateral weakness, spasticity, hyperreflexia and positive Babinski signdorsal column damage causes ipsilateral loss of proprioception, vibration and discriminative touchspinothalamic tract damage causes contralateral loss of light touch, pressure, pain and temperature.At the level of the Brown-Séquard lesion: damage to the ventral horns causes ipsilateral muscle weakness with flaccid paralysis and hyporeflexia.
Quantitative Sensory Testing (QST) Estimation of Regional Cutaneous Thermal Sensitivity During Waking State, Neutral Hypnosis, and Temperature Specific Suggestions
Published in International Journal of Clinical and Experimental Hypnosis, 2019
Gianluca Conversa, Enrico Facco, Matteo Luigi Giuseppe Leoni, Michelangelo Buonocore, Rosa Bagnasco, Lucia Angelini, Laura Demartini, David Spiegel
Temperature is detected by transient receptor potentials (TRP) receptors located at free nerve endings of the skin. The signal is then transmitted through the spinothalamic tract up to the medial (emotional and symbolic aspects of pain) and lateral (pain perception) components of the pain neuromatrix (Iannetti & Mouraux, 2010; Melzack, 2001). C fibers (polimodal nociceptors) transmit chemical, mechanical, and thermal information, while Aδ fibers (nociceptors) convey cold sensitivity and heat/cold pain when the temperature is above a threshold level (Schepers & Ringkamp, 2010). Lesions of these fibers lead to temperature perception being decreased (Treede et al., 2008), while a persistent input (e.g., in case of phlogosis) may cause hypersensitivity with primary allodynia. Thermal allodynia and thermal sensitivity can be quantified by quantitative sensory testing (QST), which is considered the gold standard tool (Rolke, Baron, et al., 2006).
Safety considerations for the management of cholestatic itch
Published in Expert Opinion on Drug Safety, 2021
The pathophysiology of cholestasis-induced pruritus has not been completely elucidated. It seems that a common first step for all cholestatic disorders is the activation of nerve endings and skin receptors by pruritogens. This signal is then transduced to secondary neurons in the dorsal horn of the spinal cord crossing to the contralateral side to project through the spinothalamic tract to the ventromedial nucleus of the thalamus and end at the primary sensory cortex, supplementary motor area, anterior cingulate cortex and parietal lobe [10]. Although this pathway and the involved anatomic structures are well defined, many questions regarding its activation, function and regulation are yet to be answered. Bile salts/acids, endogenous opioids, histamine, serotonin, substance P and even nitric oxide have been proposed as inducers of the itch stimuli but extensive research has failed to show a linear and consistent correlation between their concentration and the intensity of symptoms [11,12].
Endoscopic endonasal resection of a medullary cavernoma: a novel case
Published in British Journal of Neurosurgery, 2019
Puya Alikhani, Sananthan Sivakanthan, Ramsey Ashour, Mark Tabor, Harry van Loveren, Siviero Agazzi
Recent advancements in neuroimaging, namely diffusion tensor tractography, have provided surgeons additional information to aid in operative decision making. It has been demonstrated that the cerebellar peduncles, corticospinal tract, corticopontine tracts, medial lemniscus, lateral lemniscus, spinothalamic tract, rubrospinal tract, central tegmental tract, medial longitudinal fasciculus, and dorsal longitudinal fasciculus can all be reliably and reproducibly tracked using diffusion tensor imaging.11 With this anatomical information, direction of fiber pathway displacement can now be utilized to supplement traditional imaging to formulate the best operative approach. In our case, both location of the cavernoma at the anterior surface of the medulla and the posterolateral deflection of the brainstem tracts was a key factor that contributed to the decision to undertake a purely ventral entry zone into the brainstem, thereby ignoring the classic safe entry zone location into the medulla oblongata. An expanded endoscopic transclival approach was chosen to access the ventral medulla (Figure 2).
Related Knowledge Centers
- Postcentral Gyrus
- Somatosensory System
- Ventral Posterolateral Nucleus
- Thorax
- Spinal Cord
- Neck
- Pain
- Thalamus
- Somatotopic Arrangement
- Lumbar