Emergency Cranial Radiological Assessment

The Society of Neurological SurgeonsBootcamp

Objectives

• Identify basic intracranial structures

• Identify brain shift, intracranial hemorrhage, and skull fractures

• Be able to communicate accurately to the chief resident or attending the important findings that may impact clinical decision making and emergent patient management.

CT Scan

Bone Window Soft Tissue Window

Foramen spinosum

Foramen ovale

Carotid canal

Mastoid air cells

Jugular fossa

Carotid canal

Sphenoid sinus

Suprasellar

Interpeduncular

Ambient

Cisterns

Thalamus

Internal capsule

Caudate

Choroid Plexus

CT Scan

• Computerized Axial Tomography or CT scan is the most often used emergency imaging study in neurosurgery. A CT scan is an excellent study for identifying intracranial hemorrhage and skull fractures.

• Calcified structures such as bone or the pineal gland appear white or hyperdense.

• Acute blood clot appears white or hyperdense. Chronic hematomas appear dark or hypodense.

• Ischemic strokes are hard to identify on CT until they are about 6 – 12 hours old.

Hematomas

• Epidural Hematoma (EDH)• Subdural Hematomas (SDH)• Subarachnoid Hemorrhage (SAH)• Intracerebral Hemorrhage (ICH)• Intraventricular Hemorrhage (IVH)

Epidural Hematoma– Between the skull and the dura. – Biconvex or lens shaped.– More common in children and young adults.

Uncommon in the elderly since the dura is very adherent to the skull.

– Over 90% are associated with a skull fracture. Classically due to laceration of the middle meningeal artery.

– Initial concussion - “lucid interval” - deterioration– Treatment is usually emergent surgery.

Case Example: 6 year old girl, MVA, GCS 7T, LOC at scene, lucid interval, now with lethargy and left side weakness

Taken to OR for emergent evacuation of EDH

Acute SDH• More likely to be “crescent shaped” than

“lens shaped”.

• Often holohemispheric.

• Can extend along falx or tentorium.

• Does not cross the midline.

• Higher morbidity and mortality than EDH due to additional underlying brain injury.– 50-90% mortality.

Subdural Hematoma: Clot age and CT Imaging Characteristics

Acute ChronicSubacute

Chronic SDH• 50% without significant history of trauma

• Hypodense/isodense crescent shaped collection

• Evacuate if symptomatic

• Looks like motor oil

• Often occurs in the elderly on aspirin, plavix, or coumadin

• Can be treated by twist drill craniostomy, burr hole or craniotomy

Subarachnoid Hemorrhage

Subarachnoid Hemorrhage: Pattern Recognition

ACoA Aneurysm Perimesenchephalic syndrome

Diffuse SAH

55 year old male, fell off ladder, no LOC, mild headache

Repeat head CT stable, discharged next day with routine follow up

Traumatic SAH

Intracerebral Hemorrhage: Chronic Hypertension

Intracerebral Hemorrhage

• Hypertensive IPH – 50% in basal ganglia – 15% thalamus

– 10-15% pons

IPH, IVH, Acute Hydrocephalus

Lobar Intracerebral Hemorrhage:

Intraventricular HemorrhageFrontal Horn Temporal Horn Lateral Ventricle

FrontalThirdFourth

Occipital Horns

Intraventricular HemorrhageAneurysmal SAH w/ IVH HTN w/ IVH

Traumatic Contusions

• Coup or contra-coup contusion

• Hemorrhagic contusions can enlarge or “blossom” as well as develop extreme edema, so must follow examination closely and consider repeat CT scans

• Surgical evacuation if there is excessive mass effect

47 year old gentleman, was inebriated, fall, LOC, GCS 7T (E2, M4, V1T), PERRL, In cervical collar

EVD placed, Medical management of ICP, gradually improved over several days, neck cleared after extubation and improvement in neuro status

18 year old male, shot in head while sitting in car, GCS 15 with no focal deficits, open scalp wound over skull fracture

Scalp debrided, bullet fragment extracted, wound closed

7 year old boy with posterior fossa tumor, drowsy, less responsive through the day

EVD placed, immediately better

Acute Hydrocephalus

EVD

Ischemic Stroke

• Typically follow a vascular distribution such as the territory of the MCA, PCA or ACA.

• A stroke may take several hours before it is apparent on a CT scan.

• Typically is seen earlier on an MRI

MCA Infarcts

Infarct with a Midline Shift

Cerebral Edema

• Loss of Grey/White Differentiation

• Cisternal Effacement

• Midline Shift

Cerebral Edema

• Vasogenic: from brain tumor– BBB disrupted– Responds to

steroids• Cytotoxic: from

trauma– BBB closed– NO steroids

Basal Cistern Effacement

Normal Tight Swollen Brain

49 y/o male, MVA GCS 3T with fixed/dilated pupils

No improvement, pronounced brain dead 24 hours later

Fractures

• Linear

• Depressed

• Open Depressed

• Basal Skull Fracture

Depressed Skull Fracture

Open Depressed

Skull Fracture

Open Depressed

Skull Fracture s/p

MVA

Reconstruction

Basilar Skull

Fracture

Basilar Skull Fracture of the Temporal Bone Seen on Bone Windows

Basic Principles of MR Imaging• Images are created based on signals returning from spinning

protons

• Not based on density

• Objects are described in terms of intensity (hypointense, isointense, hyperintense)

• T1 and T2 Weighted Imaging

• T1 Post Contrast Enhancement

T1 Weighted Image of the Normal Brain

T2 Weighted Image of the Normal Brain

MRI: Views in different planes

Axial Sagittal Coronal

T1 Post Gadolinium Image of a Brain Tumor

Diffuse Axonal Injury (DAI)

Magnetic Resonance Imaging: Stroke • Diffusion Weighted Imaging:

– Ischemia

– Cytotoxic edema

– Increase in signal as soon as 5-10 minutes after stroke onset

Left: DWIRight: ADC map