PARALLAXIS 



he position of the observer, or by looking at it al- 



lately with one eye, then with the other ; in the latter 



case the object seems to move. P., Binocular, the 



le of convergence of the visual axes. P., Mental, 



_;ht personal equation in observation due to one' s 



standpoint. See Equation, Personal. 



jrallaxis {par-al-aks' -is) [rrapd/./.a^c, alternation ; 



i, beside; a/./.oc, other]. I. The overriding or 



tapping of the ends of a fractured bone. 2. Con- 



m of mind ; mental aberration. P., Crossed. 



. mymof/"., Heteronymous. P., Heteronymous, 



ih'e apparent shifting of an object toward the side of 



the covered eye. P., Homonymous, the movement 



■f the object toward the side of the uncovered eye. 



Irallel {par f -al-el) \_-apd7.7.rf/oc ; izapa, beside ; a/.'/.or, 



mother]. Having the same direction or course. P. 



fissure. See Fissures, Table of. 



'. rallela [par-al-el'-ah) \_^apa.7jjj7MC, parallel]. A 

 caly eruption on the palms of the hands, disposed in 

 >arallel lines. 

 I rallelism {par'-al-el-izm). See Isopathy. 

 '. ralogia { par-al-cr" -je-ah) \_~apa, beside; Aoyoc, rea- 

 on]. Difficulty in thinking logically. P., Thematic, 

 i condition in which the thought is unduly concen- 

 rated on one subject. It characterizes the individual 

 .vith a hobby. 



] ralogism {par-al' -o-jism) [rrapd, beside ; 7.6yog, rea- 

 on]. The logical error of considering effects or un- 

 dated phenomena as the causes of a condition. 

 3 ralysant ( par-al-i'-zant). See Paralyzant. 

 '. ralysis (far-al'-is-is) [-apa, beside; 7.vtiv, to loosen]. 

 \ complete loss or great diminution of the power of 

 notion in one or in a number of muscles, or of sensa- 

 tion in a part, or of both motion and sensation. P., 

 Acute Ascending, Landry 's Paralysis ; palsy be- 

 ginning in the feet and ascending to the other muscles 

 of the body, and finally involving the medulla. There 

 10 pain, and no trophic changes ; the knee-jerk is 



Finally diminished; the sphincters are uninvolved. 

 he pathology is obscure, and the malady is a very fatal 

 one, usually terminating in death within a week, 

 although it may continue for three or four weeks. 

 Males are more frequently attacked than females, and 

 •he affection occurs chiefly between the ages of twenty 

 ind forty. See also Landry s Paralysis, and Diseases, 

 Table of. P., Acute Atrophic. See P., Infantile. 

 P., Acute Progressive. Synonym of P., Acute 

 Ascending. P. agitans, Shaking Palsy ; Parkinson 1 s 

 Disease ; an affection marked by tremor or alternate 

 :ontraction and relaxation of the muscles of the part 

 nvolved. The movements are regular and rhythmic 

 distinction from insular sclerosis), and begin usually 

 n one hand. They almost never affect the head. 

 They persist during rest and are little influenced by 

 voluntary movement. Later in the disease there is 

 i typical gait, known as festination or propulsion. 

 It consists in a progressive increase in the rapidity 

 l')f the gait until the patient breaks into a run, which 

 grows faster and faster until he either falls or seizes 

 some support. This peculiar gait is ascribed to the 

 lent position of the trunk which throws the head so 

 ar forward as to bring the center of gravity beyond 

 he line of the feet. Rarely the movement is back- 

 ward; this is called retropulsion . It may be to one 

 )r the other side — later opulsion. The speech is 

 •low, monotonous and high-pitched. The face is 

 ixed and expressionless. In advanced stages there 

 = an almost statue-like rigidity of the body. The 

 land assumes a peculiar position, as if rolling a 

 ;mall body between the thumb and the fingers, but 

 ater the position becomes constant, similar to that in 

 which the pen is held — hence the term of writing 



973 PARALYSIS 



hand. The knee-jerk may be exaggerated. Flushing 

 and heat are sometimes complained of. The course is 

 of long duration, the disease at times lasting twenty 

 or thirty years. The lesion is probably a diffuse 

 sclerosis of the brain and spinal cord. Paralysis agi- 

 tans is most common in males over forty years of age. 

 P., Alcoholic, a multiple neuritis due to alcohol. 

 See Xeuritis, Multiple. P., Alternate. See Hemi- 

 plegia. P., Analgesic, with Whitlow. See Morvari s 

 Disease. P., Anapeiratic. See Fatigue-diseases, and 

 Professional Neuroses. P., Angeioneurotic {of the 

 auditory nene), a disturbance of the circulation in the 

 internal ear characterized by sudden pallor of the face, 

 nausea, tinnitus aurium, partial deafness, and vertigo, 

 the symptoms disappearing rapidly. P., Antero- 

 spinal. Synonym of Poliomyelitis, Anterior. P., 

 Arsenical, a paralysis due to a multiple neuritis caused 

 by arsenical poisoning. P., Association. Synonym 

 of P., Glosso-labio-laryngeal. P., Atrophic (of 

 children). Synonym of P. , Infantile. P., Atrophic, 

 Infantile. Synonym of P., Infantile. P., Atrophic, 

 Spinal. See P., Infantile. P., Bell's, a paralysis of 

 the facial muscles arising from a lesion of the seventh, or 

 facial nerve. This lesion may be on the face, in the 

 temporal bone, or within the skull. Very rarely the 

 affection is bilateral. P., Brachial, a paralysis of 

 one or both arms. It may be due to a lesion of the 

 brain-cortex, the spinal cord, or the nerves of the 

 brachial plexus or their roots. P., Brown-Se- 

 quard's. See Diseases, Table of. P., Bulbar, Glosso- 

 labio-laryngeal paralysis ; a form of paralysis due to 

 a degeneration of the nuclei of origin of the nerves 

 (facial, glosso-pharyngeal, vagus, spinal accessory, and 

 hypoglossal) arising in the oblongata. At first only 

 the muscles of the lips, tongue, and pharynx are af- 

 fected. The disease is marked by difficulty in masti- 

 cation, deglutition, respiration, phonation, and articula- 

 lation, and by wasting of the muscles concerned in the 

 performance of these functions. The condition is 

 sometimes a sequel to exposure to severe cold ; it may 

 be caused by morbid growths or by syphilis. It is 

 usually confined to the latter half of life, and its 

 prognosis is bad. P., Caisson. Synonym of Caisson- 

 disease. P., Central, a paralysis due to a brain-lesion. 

 P., Centro-capsular, a paralysis due to a lesion of 

 the internal capsule. P., Centrocortical, one caused 

 by a lesion of the cerebral cortex. P., Cerebral, a 

 paralysis due to a brain-lesion. P., Cerebral Infan- 

 tile, P., Cerebral {of childhood), a spastic paralysis 

 of children due to a lesion of the brain. It is often 

 caused by the use of the forceps at birth. P., Cortical, 

 a paralysis due to a lesion of the cerebral cortex ; it 

 is usually a monoplegia or a hemiplegia. P., Crossed : 

 I. A paralysis of the arm and leg of one side, associated 

 with either a facial paralysis or a paralysis of the 

 oculo-motor nerve of the opposite side, due to a lesion 

 involving the pyramidal tracts of the side before they 

 have crossed in the medulla, and a cranial nerve, e.g., 

 the third, the sixth, or the seventh, after its fibers of 

 origin have decussated. 2. Paralysis of the arm on one 

 side and of the leg on the other. P. cruciata. Synonym 

 of P., Crossed. P., Crutch. See Crutch-paralysis. 

 P., Cruveilhier's, progressive muscular atrophy. P., 

 Dental, anterior poliomyelitis occurring in teething 

 children, formerly attributed to disturbed dentition. 

 P., Diphtheric, a form sometimes occurring in patients 

 convalescent from diphtheria. It is primarily a multi- 

 ple neuritis caused by the toxin of diphtheria. P.. 

 Divers'. See Caisson-disease. P., Duchenne's. 

 See Duchenne's Disease in Diseases, Table of. P., 

 Emotional, a hysteric paralysis due to emotional 

 excitement. P., Erb's. See Erb, and Diseases, 



