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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.

 

Brainspace.png

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


     

Fig1-1.png

 

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Fig6-1.png

 

Fig7.png
 

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.

 

Fig8.png

* 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/

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