S34 DISORDERS AFFECTING MOTION AND SENSATION. 



Convulsions are muscular spasms of more severity, and 

 affecting a greater extent of structure, but are in their essen- 

 tial nature similar. Spasms and convulsions affect all the 

 muscles supplied by the cerebro-spinal axis, and probably also 

 those animated by the sympathetic system. 



The term eclampsia is apphed to a development of muscular 

 spasms or convulsions partaking of the epileptic or epilepti- 

 form character, in which the involuntary muscular contrac- 

 tions are accompanied with loss of perception and volition. 

 These convulsions are usually tonic at first, afterwards of a 

 clonic character, and are of a more serious nature than ordi- 

 nary convulsive movements. 



Causation. — All these phenomena of motor disturbance are 

 probably referable to interference with some portion or other 

 of the nervous centres, this interference extending merely to 

 irritation inducing discharges of nerve-force not reaching the 

 extent of destruction of nerve-tissue. 



The chief causes in the production of these discharging 

 lesions are — 1. Centric, as traumatic lesions, or lesions result- 

 ing from diseases of the cranial walls, organic diseases of the 

 cranial structures, circulation of impure blood through the 

 nervous centres, or other dynamic changes unconnected with 

 visible alterations, but probably dependent on disturbed nutri- 

 tion. 2. Eccentric, or sympathetic. Here the inducing fac- 

 tor is irritation, propagated from disturbance or disease of a 

 variably situated organ or structure, to a nervous centre. It 

 may arise from gastric or intestinal disturbance incident to 

 parasites, to some irregularity of functional performance, or to 

 an injury sustained in a distant part. 



Treatment. — When medical interference is desirable, the 

 indications are — 1. To relieve the severity of the existing con- 

 vulsions, and in all tits of an epileptiform character to prevent 

 the animal doing himself injury. 2. To ascertam if there is 

 any condition of an abnormal character of temporary occur- 

 rence, as irregularity of dieting, which might operate in a 

 reflex manner in inducing the spasms. 3. If any constitu- 

 tional cachexia or acquired impurity of blood is believed to 

 exist, by good food and tonics to operate against the tendency 

 of the one, and by appropriate medicine to eliminate the con- 

 taminatincf airent of the other. 



