162 CLINICAL APPLIED ANATOMY. 



suffer most because their circulation is absolutely terminal and 

 without anastomosis, whilst the amount of cortical anastomosis 

 varies in different individuals. 



The symptoms of tuberculous meningitis correspond, in the 

 main, to the visible distribution of the lesions. The cranial 

 nerves of that part of the base affected usually suffer fairly early 

 in the disease ; the third, sixth and seventh are most commonly 

 picked out ; and squints, ptosis, and facial paralysis of the 

 complete nuclear type result. Partial facial paralysis of the 

 cortical type is due to extension of the inflammation along 

 the Sylvian fissures and towards the convexity of the hemispheres. 

 The prodromal aphasias and mental disturbance are attributed to 

 cortical oedema which may be transitory. Later on convulsions, 

 coarse tremors and rigidities point to cortical invasion, as also do 

 paralyses of hemiplegic or monoplegic distribution. 



Head retraction is usually moderate and caused by extension 

 of inflammation to the posterior part of the base. The coma 

 may be explained by increasing ventricular distension. Throm- 

 bosis of the cerebral veins and sinuses is rare ; since the veins 

 of the cortex, unlike the arteries, communicate freely. 



Tuberculous spinal meningitis is usually secondary to or 

 associated with meningitis of the cerebral meninges, the mem- 

 branes of the brain and cord being directly continuous. Like 

 the cerebral form, the spinal variety is a leptomeningitis 

 accompanied by effusion into the space between the pia and the 

 arachnoid. Owing to the dorsal posture assumed in the later 

 stages of the cerebral lesion, the morbid changes are best marked 

 on the dorsal aspect of the cord, and the posterior sensory nerve 

 roots are especially apt to suffer. The peripheral zone of the 

 cord itself may be invaded along the paths afforded by the pial 

 septa, the anterior and posterior roots, and the vessels which 

 enter the margin of the cord from its pial investment. 



Diffuse syphilitic meningitis usually originates in the pia 

 and arachnoid as a rich cellular infiltration. The lesion, however, 

 is not limited to the leptomeninges, but spreads along the vessels 

 of the pia to the brain tissue on the one hand and to the adjacent 



