Evaluation of Plain X-ray SkullA Systematic ApproachBy Dr. Tarek Mansour

•The skull is a rounded layer of bone designed to protect the brain from penetrating injuries.

ANATOMY • Formed of 22 bones• 1 movable: Mandible.• 21 fixed & articulating with

fibrous joints: 5 unpaired: Ethmoid,

sphenoid, vomer, frontal and occipital.

8 paired: parietal, temporal, zygomatic, lacrimal, maxillary, nasal, palatine & inf. concha.

ANATOMY •1.Cranium: upper

and posterior parts which enclose the brain.

•2.Facial skeleton: anterior part of the skull.

ANATOMY BONES :•Frontal bone

anteriorly.•Parietal bones on both

sides.•Occipital bone

posteriorly.

ANATOMY Sutures:•Coronal suture•Sagittal suture.•Lambdoid suture.

•Range in size 1.5 mm. up to 10 mm at birth. After few ms, reach less than 3mm

ANATOMY

Fontanelles:•Anterior (Bregma):

1.5y•Posterior (lambda):

6ms.

ANATOMY•Upper part:

Frontal bone.

•Middle part: 2 orbital cavities and nasal cavity.

•Lower part: upper and lower jaw.

ANATOMY• BONES: Frontal bone, 2

zygomatic bones, nasal bones, 2 maxillary bones, mandible.

• SUTURES: fronto-nasal, fronto-zygomatic, fronto-maxillary, zygomatico-maxillary.

ANATOMY•Frontal process.

•Maxillary process.

•Temporal process.

•Orbital plate.

ANATOMY•Frontal process.

•Zygomatic process.

•Alveolar process.

•Palatine process.

•Orbital plate.

ANATOMY•Superiorly: nasal,

frontal and parietal bones.

•Inferiorly: maxilla, Zygomatic, gr. Wing of sphenoid, sq. & mastoid parts of temporal bone and occipital bone.

ANATOMYPARTS: Supra temporal area. Temporal fossa. Infra-temporal fossa.

Imp. Landmarks: • Pterion. • Asterion.• Ext. aud. meatus. • Mastoid process. • Zygomatic arch

ANATOMYBONES :• 2 Parietal bones.• 2 Mastoid temporal

bones.• Occipital bone.

Sutures:• Lambdoid suture.• Occipito-mastoid suture.

ANATOMY• Divided in to anterior,

middle and posterior parts by 2 lines:

Ant. Line along post. Border of hard palate.

Post. Line through post. Border of foramen magnum.

ANATOMY• Divided in to anterior,

middle and posterior parts by 2 lines:

Ant. Line along post. Border of hard palate.

Post. Line through post. Border of foramen magnum.

ANATOMYAnterior Part:

• Hard palate:

• Anterior 2/3: palatine process of maxilla.

• Posterior 1/3: palatine bone.

ANATOMYAnterior Part:

• Hard palate:

• Anterior 2/3: palatine process of maxilla.

• Posterior 1/3: palatine bone.

ANATOMYMiddle Part:

• Ant. mid: Vomer & body of sphenoid.

• Ant. Lat.: pterygoid process & Gr. wing of sphenoid.

• Post. Lat.: petrous bone.• Post. Mid: occipital

bone.

ANATOMYPosterior Part:

External occipitalprotuberance.Insertions of muscles .

ANATOMYImp. foramina:F. Ovale : AMA, Mand.

N motor root of 5 th CN.

F. Spinosum : MMA.Carotid canal : ICA.Jugular F .: IJV, inf.

petrosal sinus, 9 th ,10 th & 11 th CN.

F. Magnum..

ANATOMY

ANATOMY•Divided into anterior, middle and posterior cranial fossa.

ANATOMY•Anterior cranial fossa:Anterior :•Orbital plates of frontal

bone.•Cribriform plate of

ethmoid bone.Posterior :•Lesser wing of sphenoid,•Planum sphenoidal.

ANATOMY•Middle cranial fossa:Middle :• Sella Turcica (body of

sphenoid).Sides :• Gr. wing of sphenoid,• Petrous temporal

bone.• Sq. temporal bone.

ANATOMY•Posterior cranial fossa:Anterior :• Body of sphenoid articulating

with basilar part of occipital bone ( Clivus ).

On sides :• petrous and mastoid parts of

temporal bone.Posterior :• Squamous part of occipital

one.

Blood Vessels of the Skull• The brain requires a rich blood

supply, and the space between the skull and cerebrum contains many blood vessels.

• These blood vessels can be ruptured during trauma, resulting in bleeding.

Skull radiograph (X ray).

Positions:

1 .Lateral.2 .PA view.

3 .Towne’s view.4 .Basal view.

Others:o Optic foramen.o Sinuses.o Mastoids.o Petrous bones.o Coned pituitary fossa.

Indication for skull radiographs •Evaluation of skeletal dysplasias.•Diagnostic survey in abuse.•Abnormal head shapes.•Infections and tumors affecting the skull

bones.•Metabolic bone disease, leukemias and •Multiple myeloma

X rays positions•Lateral view of the skull.•Frontal view.•Towne`s view.•Basal view.•Water view.•Caldwell`s view.

Lateral skull view•Commonest plain x ray view•Should examine:

1.Size & shape.2.Thickness and density of the bone.3.Sutures and vascular marking.4.Base of skull and cranial cavity.

Lateral:•Head in true lat position.•Center over the pit. fossa (1 cm

above OML & 2.5 ant to EAM).

• Normal lateral view of skull demonstrates the normal coronal sutures, lambdoid sutures and the vascular grooves due to middle meningeal vessels posterior to coronal sutures. Note the two lines formed by the roof of the orbits ending posteriorly at the anterior clinoid processes. Arrow head marks the tuberculum sellae. Vertical arrows (anterior) show the cribriform plate and the (posterior) planum sphenoidale. Open arrow shows the greater wing of sphenoid bone forming anterior borders of middle cranial fossa. The dorsum sellae (horizontal arrow) with posterior clinoid processes above and the clivus posteriorly are well seen

Frontal (AP) view.

•OML should e vertical.•PA with 20 degree caudal tilting.•Center on the inion.

Frontal view• PA view with 15° caudal

angulation demonstrates the dense vertical bony projection in the midline due to crista galli, lesser wings of the sphenoid on both sides joining to form the planum sphenoidale (arrow heads). Floor of sella is faintly visualized in the midline (vertical arrows). Oblique line of the orbit is formed by the greater wing of sphenoid in its lower two-thirds and by the frontal bone in its upper one-third

Towne’s view:

•AP with 30 degree caudal tilting.

Towne`s view• Towne’s view shows

foramen magnum in the center with dorsum sellae projecting through it. The parallel lucencies (short arrows) on either side represent the internal auditory canals. Further laterally pneumatized mastoids air cells can also be seen

Basal (PA) view:•Hyperextension of he head.•Anatomical base line horizontal.•Center vertical to it & between angles of

mandible.

Basal view• Basal view of skull shows the

nasopharynx, sphenoid sinus and ethmoid sinuses in the midline. Posteriorly odontoid process is seen to project into the foramen magnum posterior to the arch of atlas. Laterally, the foramen ovale (open arrow) foramen spinosum, (long arrow), eustachian tube posterior to foramen spinosum and the carotid canal are well visualized. Antero-laterally, the three lines formed by the posterior wall of orbit (arrow head) maxillary sinus (S-shaped) (curved arrow) and the anterior wall of middle cranial fossa (thick arrow) (arched shadow with concavity posteriorly) should be looked for in each case. Medial and lateral pterygoid plates are well seen

Sinuses.•They are rudimentary

at birth and increase in size with age, reaching full development in adult skull.

•Anterior and posterior groups.

•Variations & pneumatization.

Waters view

• Waters view of skull shows bilateral maxillary antrum (lower horizontal arrows), frontal sinuses (vertical arrows), ethmoid sinuses (upper horizontal arrows) and lower margin of sphenoid sinuses (arrowheads)

•Pineal.•Choroid plexus.•Dura (Falx, tentorium, over vault).•Ligaments.•BG.•Pit. gland.•Lens.

Skull plain x ray abnormalitiesSkull X-rays can be categorized in the following

groups:

1.Abnormal density2.Abnormal contour of the skull3.Abnormal intracranial volume4.Intracranial calcification5.Increased thickness of the skull6.Single lucent defect7.Multiple lucent defects8.Sclerotic areas.

Abnormal skull contourNormal skull contour is maintained by:• Sutures.• Intracranial contents.• Normal bone formation.

• Craniosynostosis is the commonest cause of abnormal skull contour.

• A simple method of assessing the size of the skull is to compare the skull vault to the size of the face.

At birth 4:1At 2 years 3:1At adulthood 1.5:1

•It is important to differentiate premature closure of all sutures from microcephaly with fused sutures.

•When multiple sutures fuse prematurely 1- The suture not fuse symmetrical so it

result in irregular skull.2- Signs of raised intracranial tension.3- Exaggerated convolutional marking.

• Craniosynostosis: AP view of skull shows silver beaten appearance due to exaggerated convolutional markings all over the skull vault. None of the sutures are seen

•Hemolytic anemia (thalassemia) caused.•1- Wide diplioc space with striking radial

striation (hair-on-end) appearance.•2- Obliterated paranasal sinuses.

•Other forms of anemia shows the same changes but less marked (sickle cell disease, hereditary spherocytosis).

• Thalassemia: Lateral skull radiograph shows widened diploic space with coarsened trabeculae giving “hair-on-end” appearance typical of hemolytic anemia

Single radiolucent defectIf lytic lesion noted we should evaluate:

•Location.•Associated soft tissue.•Involved skull table.•Margin

Sharp.Ill defined.Sclerotic.

• Craniolacunia: Lateral skull radiograph in an infant shows multiple lucencies with intervening dense areas typical of craniolacunia.

• Note the associated occipital encephalocele and absence of sutural widening

• Depressed fracture: Frontal radiograph shows the parallel dense lines due to depressed bone fragments and associated lucency due to absence of bone

• Growing fracture: PA skull radiographs in a child demonstrate fracture of the right frontal bone with thickening, sclerosis and wide separation of the fracture ends. Note the soft tissue swelling overlying this area

• Dermoid scalp. Skull radiograph shows a well circumscribed lucency overlying the coronal suture

Osteosarcoma: (A) Large lytic area with irregularmargin is seen affecting the left parietal bone. (B) CT scan of the same patient shows the soft tissue swelling, destruction of the bone and extradural extension of the tumor

• Diffuse metastasis of skull vault: Lateral skull radiograph shows multiple lytic areas involving both tables of skull and diploic space. Note widening of coronal suture also

• Multiple myeloma: Lateral skull radiographs shows multiple well-defined punched out lytic lesions affecting the skull vault as well as mandible typical of myeloma

Hyperparathyroidism: Lateral skull radiograph shows multiple lytic lesions with mottled appearance

Hyperparathyroidism: Lateral skull radiograph shows multiple well circumscribed rounded lytic lesions involving skull vault with bone within bone appearance an unusual feature of hyperparathyroidism

Sclerotic areas of the skull•Osteopetrosis.•Fibrous dysplasia.•Paget disease.•Rickets.•Osteoma.•Meningioma.•Hyperostosis frontalis interna.

• Osteopetrosis: Frontal radiograph shows diffuse increased density affecting all bones of the skull vault as well as base

Sphenoid wing meningioma: (A) PA view of skull shows hyperostosis of the left lesser and greater wings of the sphenoid bone typical of meningioma. (B) Contrast enhanced CT scan in the same patient shows proptosis and hyperostosis of sphenoid wings with enhancingextradural mass due to meningioma on the left side

Fibrous dysplasia: Frontal view of skull reveal sclerotic lesion involving the frontal bone. The frontal sinus is opaque. Axial CT scan in the same patient shows expanded sclerotic frontal bone

Paget disease: Lateral view of skull reveal focal areas ofopacities in previous areas of osteoporosis giving “cotton wool” appearance

Osteoma: Waters view of skull shows osteoma of the frontal sinus

• Hyperostosis frontalis interna: Lateral skull radiograph shows irregular thickening of the frontal bone in an elderly female. The inner table is involved more than the outer table with sparing of diploic spaces

Sturge-Weber syndrome: PA (A) and lateral (B)view of the skull shows gyriform calcification on the left side