CT scan in head and spine injuries BY : DR AHMED MOHAMMED DEBES

NEUROSURGERY RESIDENT AT AHMED MAHER TEACHING HOSPITAL

CAIRO, EGYPT

Brief history

Basic physics

mapped onto Hounsfield scale from –1000 (black) to + 1000 (white).

the brain tissue is the point of reference.Any tissue “whiter” than brain tissue is

hyper densewhile any tissue “blacker” than brain tissue is hypo dense

Hounsfield Units

tissue’s attenuation coefficient the ability

to “block” X-rays. relatively constant

Image acquisition

LOOK for

I - Skull Fracture

II –Pneumo-cephalus

III -Hematoma

IV -Cerebral Edema

V -Herniation

What to look for in CT scan brain of a head trauma patient ?

I - Skull Fracture

Look in head CT bone window

I - Linear, non-depressed

fracture

II - Depressed fracture

Consider open when

- Skin laceration over the fracture

- Through par nasal sinuses, middle

ear structures

Surgical elevation in

- Depressed > 5 mm and overlies

motor or speech areas

- Depressed > skull thickness

Causes laceration of Dura, arachnoid

and possible brain parenchyma

III - Diastatic fracture

Spreading of suture, 1-2 mm more

than normal contralateral side

May tear Dural venous sinus

IV - Basilar fracture

Presentations

- CSF otorrhea, bruising over

mastoid (Battle sign)

- CSF rhinorrhea, bruising around

the eyes (raccoon eyes)

II - Pneumocephalus

Presence of air in the cranial cavity

Indicates communication between

intracranial and extra cranial spaces

complications:

meningitis, CSF otorrhea or rhinorrhea

III - Hematoma

I - Epidural Hematoma

Source of bleeding

most commonly middle meningeal

artery

Don't cross sutures

Hyper dense biconvex extra-axial

mass

II - Subdural Hematoma

Source of bleeding

torn cortical bridging veins

Hyper dense crescent blood

collection

Can cross suture

Can extend into interhemispheric

fissure

III - Traumatic Subarachnoid

Hemorrhage

Source of bleeding

Tear of veins in subarachnoid space

High density blood in sulci/cisterns

IV - Cerebral Contusion

due to cerebral gyri impact inner

table of the skull

Evolve from petechial hemorrhage ->

small hemorrhage ->large hematoma

Multiple, bilateral

MRI is better for detection

III - Cerebral Edema

Generally resolves within 2 weeks

- loss of grey/white matter interface

- compressed ventricles

- effacement of the sulci

IV - Herniation

I - Midline Shift & Subfalcine

Herniation

Subfalcine herniation is herniation of

Cingular gyrus underneath the falx

cerebri.

Presence of midline shift usually

signify Subfalcine herniation, and vice

versa.

II - Transtentorial herniation

Central herniation is defined as both

temporal lobes descend through the

tentorial incisura

Effacement of the cistern

around the midbrain

III - Tonsillar Herniation

- obliteration of CSF space

- displaced portions of cervicomedullary junction

CT scan in spine trauma

I - Compression fracture

II – Burst fracture

III – Flexion fracture

III – fracture dislocation