Localization of Lesion in Special Symptoms. 13 



in their area of distribution, nature (spasm, paralysis) and per- 

 manency. Objective Symptoms predominate and the case is likely 

 to be progressive and fatal. 



Functional Nervous Diseases have symptoms of indefinite 

 di.stribution, variable in character, with intermis.sions and spon- 

 taneous disappearances (as under marked excitement) and sub- 

 jective symptoms predominate. They may, however, last for a 

 length of time without change. 



Localisation of Brain Lesions. 



Lesions of the cranial nerves and .their superficial and deep 

 centres of origin need not here occupy attention. These may be 

 studied in vt'orks on anatomy and phy.siolog}'. Attention may be 

 drawn rather to the remoter effects of ganglia which affect or 

 control distant action, and to general pressure on the encephalon. 



General Pressure on the Encephalon, whether through 

 fracture of the cranium and depression of bone, by acute conges- 

 tion, by blood extravasation, by inflammatory exudation, or by 

 acute abscess, will cause pain, spasms, nausea, dullness, blind- 

 ness, .stupor and coma. After explusion of the cerebrospinal 

 fluid from the cranial cavity, the increasing pressure compresses 

 the blood vessels, reduces or interrupts the circulation and 

 abolishes the functions in the parts deprived of blood. Thus 

 congestion of one portion of the encephalon is usually as.sociated 

 with diminished circulation in another portion. Disorder in the 

 first may occur from hyperaemia and irritation and in another 

 part from a con.sequent anaemia. 



Destructive Lesions of Cortex of One Cerebral Hemi- 

 sphere may or may not cause permanent symptoms, as shown 

 by the passage of a crowbar through the front of the left hemi- 

 sphere, yet the man survived for 13 years and showed no loss of 

 intelligence, his di.sposition and character alone having changed 

 for the worse. The one hemisphere may by itself sufficiently 

 control mental acts, while the other lies dormant or may even 

 have undergone degeneration. 



Diagnosis of Encephalic and Spinal Lesions. The fol- 

 lowing may be taken as guiding principles : 



Encephalic : Hemiplegic or bilaterally hemiplegic grouping of 

 symptoms. 



