醫學筆記匯整 ED Notes

Evaluation of ICP using CT requires comparison of CSF spaces

Findings of high intracranial pressure are often Symmetrical

因為對稱 所以常常被 miss 掉

In addition to abnormalities of the size of CSF spaces,
other abnormalities may be present,
including loss of gray-white matter differentiation in cases of cerebral edema.

最關鍵就是要看 Ventricle, sulci, cistern 三者的平衡 !! 

都大 -- Atrophy
都小 -- Cerebral edema
V大其他小 -- Hydrocephalus
 

• Atrophy 因為 brain parenchymal volume 少了
  所以全部的 CSF space 都大
  
  老人 commonly demonstrate atrophy on head CT
  沒有 Sulci 就要想到 elevated ICP 
   
• Cerebral edema, 因為 brain parenchymal volume 增加
  導致全部的 CSF space 都小
  ( effacement of all three CSF spaces )
   
• Obstructive hydrocephalus
  the obstructed ventricular system enlarges
  effacement of sulci and cisterns 腦池 & 腦溝變小
  
   

Meningitis and SAH can precipitate hydrocephalus by creating debris

WBC, RBCs
pathogen debris such as the gelatinous coat of Cryptococcus neoformans
阻止 CSF 吸收 
 

當 CT 看到 elevated ICP
就要開始找原因

Occult underlying causes of high intracranial pressure,
include venous sinus thrombosis and meningitis.
 

* Lumbar puncture : 

IICP 當然是 contraindication
特別是伴隨 mass effect 

Ironically, several indications for lumbar puncture,

• Meningitis
• Subarachnoid hemorrhage
• Pseudotumor cerebri (idiopathic intracranial hypertension)
  
  are commonly associated with moderate elevations in ICP,
  Even with normal head CT findings.
  所以 Lumbar puncture 前, 要再次小心評估 CT 是否有 ICP

* Reconsider TPA : 
IICP 不是 contraindication for TPA 
但是 CT 上看到 IICP 常常代表 alternative cause of neurologic symptoms,
rather than ischemic stroke.

所以 Suspect stroke 的病人, 看CT 不只是排除 ICH 
也要評估 abnormal ICP

http://epmonthly.com/article/reading-head-ct-pressure/