From Big Medical Encyclopedia

AREFLEXIA (areflexia; grech, and - otritsa. + a reflex) — the lack of reflexes caused by disturbance of integrity of a reflex arc or the braking influence of overlying parts of the nervous system. And. arises at disturbance of conductivity of nervous impulses at various levels of reflex arcs: a receptor, sensitive neuron, sensitive fibers, contact neuron, motor-neuron and working body (see. Reflex ). And. along with a muscular atony and an atrophy is one of the main symptoms of a flaccid paralysis.

On prevalence And. it is classified on total (diffusion) and local and regional; on firmness of process distinguish stationary And. and passing (neurodynamic). Stationary And. it is observed at a rupture of a reflex arc at any level, passing — at various extent of braking of brain structures with the phenomena of a temporary functional asinapsiya.

A total areflexia

At total And. process strikes various levels of bark of big hemispheres, a trunk of a brain and a spinal cord. Develops at an acute injury and a stroke as a result of ultraboundary braking (see) according to I. P. Pavlov or diaschisis (see) according to C. Monakow. Total and long And., involving in process somatic and the autonomic nervous system with defeat of the trunk centers of breath and blood circulation, it is observed at an agony.

Locally - a regional areflexia

1. Isolated tendinous And. is one of signs of defeat of back columns of a spinal cord, it is observed at back to tabes and a family ataxy of Fridreykh (see. Ataxy ).

2. Pupillary And. at Argayll Robertson's syndrome arises at defeat of an internuncial neuron between upper dvukholmiy and an additional parasympathetic kernel of a third cranial nerve.

3. Pharyngeal the Ampere-second loss of a reflex from a root of language is one of components of bulbar paralysis.

4. Isolated And. a verkhnebryushny, srednebryushny or nizhnebryushny reflex confirms disturbance of a reflex arc at the level of Th segments 7 — Th 12 spinal cord.

5. Chetverokholmny And. there is in cases of pathological change of plates a chetverokholmiya and the start reflex (E. K. Sepp) in response to unexpected sound, light and tactile irritants is shown by loss defensive.

6. Skin and vegetative And. arises at the isolated defeat of cells of Jacobson in side horns of a spinal cord or a part of a sympathetic chain that is shown by lack of a reflex dermographism and disturbance of regional sweating in the corresponding zones of a vegetative dermatome. Skin And. can arise also at defeat of pyramidal system. So, disappearance of belly and bottom reflexes at the central paralyzes is observed. And. belly reflexes of conduction character at a satisfactory tone of muscles of a front abdominal wall it is characteristic of multiple sclerosis.

Bibliography: Bekhterev V. M. General diagnosis of diseases of a nervous system, p. 2, Pg., 1915; Davidenkov G. H. Spinal regulation of tendon jerks, Sovr. psikhonevrol., t. 2, No. 1, page 5, 1926; M. B. and Fedorov E. A. Crawl. Main neuropathological syndromes, M., 1966; P at l and t about in A. M. and Nikiforov A. S. Reference book on semiotics of nervous diseases, Tashkent, 1972.

A. M. Pulatov.