2. Cistern
• Widening of subarachnoid space created
by separation of pia and arachnoid.
Dura
Pia
Arachnoid
adherent to the skull
adherent to the brain surface
covers only superficial surface of
the brain
3. Cistern
• Widening of subarachnoid space created
by separation of pia and arachnoid.
Subarachnoid hemorrhage
103. Overview of CSF spaces
Normal:
All CSF spaces are visible
neither effaced or dilated.
104. Overview of CSF spaces
Normal:
All CSF spaces are visible
neither effaced or dilated.
Atrophy:
All CSF spaces are dilated.
Hydrocephalus:
Ventricles dilated.
Subarachnoid spaces
effaced.
Edema:
All CSF spaces are effaced.
105. Overview of CSF spaces
Normal:
All CSF spaces are visible
neither effaced or dilated.
Atrophy:
All CSF spaces are dilated.
106. Overview of CSF spaces
Normal:
All CSF spaces are visible
neither effaced or dilated.
Atrophy:
All CSF spaces are dilated.
Hydrocephalus:
Ventricles dilated.
Subarachnoid spaces
effaced.
107. Overview of CSF spaces
Normal:
All CSF spaces are visible
neither effaced or dilated.
Atrophy:
All CSF spaces are dilated.
Hydrocephalus:
Ventricles dilated.
Subarachnoid spaces
effaced.
Edema:
All CSF spaces are effaced.
111. Benign external hydrocephalus
benign enlargement of subarachnoid spaces in infancy
Etiology:
• Immature arachnoid granulations.
C.P:
• Macrocephaly.
• Normal developmental milestones.
112. 1. Widening of the bifrontal subarachnoid space and anterior
interhemispheric fissure (>5mm).
2. Usually normal subaracnoid space posteriorly.
3. No flattening of adjacent gyri.
4. The anterior fontanelle is frequently enlarged.
5. The ventricular system is within normal limits or slightly dilated.
6. There are no pressure effects on the surrounding brain tissue
or cerebral atrophy.
7. No blood products on MRI study.
8. another key distinction between benign enlargement of the
subarachnoid spaces and a subdural fluid collection is that in
the former the cortical veins will be adjacent to the inner table
of the calvarium on MR and ultrasound; whereas in the latter
the veins are displaced away from the inner table, as the
arachnoid membrane and subarachnoid space are displaced.
116. Hydrocephalus versus atrophy
Features that favor hydrocephalus
• Dilatation of the temporal horns
• Peri-ventricular interstitial oedema .
• intra-ventricular flow void from CSF movement on MR
• Widening of the third ventricular recesses : mid sagittal plane
• Upward bowing of the corpus callosum : mid sagittal plane
• Decreased mammillo-pontine distance : mid sagittal plane
117. Mid-sagittal findings of
hydrocephalus
• Widening of the third
ventricular recesses.
• Upward bowing of the
corpus callosum.
• Decreased mammillo-
pontine distance .
