When this happens during waking, the patient who had a cataplectic attack loses muscular control. This loss of tonus is caused by massive inhibition of motor neurons in the spinal cord.
Theories for episodes Ī phenomenon of REM sleep, muscular paralysis, occurs at an inappropriate time. The neurological process behind the lesion impairs pathways controlling the normal inhibition of muscle tone drop, consequently resulting in muscle atonia. These lesions or generalized processes disrupt the hypocretin neurons and their pathways. Cataplexy may also occur transiently or permanently due to lesions of the hypothalamus that were caused by surgery, especially in difficult tumor resections. Other conditions in which cataplexy can be seen include ischemic events, multiple sclerosis, head injury, paraneoplastic syndromes, infections such as encephalitis, and more rarely Niemann Pick disease. These lesions can be visualized with brain imaging, however in their early stages they can be missed.
Some of the tumors include astrocytoma, glioblastoma, glioma, and subependymoma. The lesions include tumors of the brain or brainstem and arterio-venous malformations. Cataplexy due to brainstem lesions is uncommon particularly when seen in isolation. Secondary cataplexy is associated with specific lesions located primarily in the lateral and posterior hypothalamus. Mechanism In this simplified brain circuit, damage to orexin-secreting neurons in the hypothalamus can lead to inhibition of motor neurons, thus lowering muscle tone.Ĭataplexy is considered secondary when it is due to specific lesions in the brain that cause a depletion of the hypocretin neurotransmitter. Cataplectic attacks may occasionally occur spontaneously, with no identifiable emotional trigger. One well-known example of this was the reaction of 1968 Olympic long jump medalist Bob Beamon on learning that he had broken the previous world record by over 0.5 meters (almost 2 feet). While cataplexy worsens with fatigue, it is different from narcoleptic sleep attacks and is usually, but not always, triggered by strong emotional reactions such as laughter, anger, surprise, awe, and embarrassment, or by sudden physical effort, especially if the person is caught off guard. If the person is reclining comfortably, they may transition into sleepiness, hypnagogic hallucinations, or a period of REM sleep. Ĭataplexy attacks are self-limiting and resolve without the need for medical intervention. Speech may be slurred and vision may be impaired (double vision, inability to focus), but hearing and awareness remain normal. Even in a full-blown collapse, people are usually able to avoid injury because they learn to notice the feeling of the cataplectic attack approaching and the fall is usually slow and progressive. Attacks are brief, most lasting from a few seconds to a couple of minutes, and typically involve dropping of the jaw, neck weakness, and/or buckling of the knees. Signs and symptoms Ĭataplexy manifests itself as muscular weakness which may range from a barely perceptible slackening of the facial muscles to complete muscle paralysis with postural collapse.
CATAPLEXY MEANING FULL
Even if he preferred the term 'astasia' instead of 'cataplexy' the case described by him remained iconic for the full narcoleptic syndrome. Nevertheless, the onset reported by him was in adulthood as compared to the nowadays cases reported in childhood and adolescence. In the same year the French neuropsychiatrist Jean-Baptiste Gélineau coined the term 'narcolepsy' and published some clinical reports that contain details about two patients who have similar condition as the narcoleptic cases nowadays. The term cataplexy originates from the Greek κατά ( kata, meaning "down"), and πλῆξις ( plēxis, meaning "strike") and it was first used around 1880 in German physiology literature to describe the phenomenon of tonic immobility also known as " playing possum" (in reference to the opossum's behavior of feigning death when threatened). Cataplexy without narcolepsy is rare and the cause is unknown.
Cataplexy affects approximately 20% of people who have narcolepsy, and is caused by an autoimmune destruction of hypothalamic neurons that produce the neuropeptide hypocretin (also called orexin), which regulates arousal and has a role in stabilization of the transition between wake and sleep states. Cataplexy is a sudden and transient episode of muscle weakness accompanied by full conscious awareness, typically triggered by emotions such as laughing, crying, or terror.
0 kommentar(er)
