1. DENTAL GROSS ANATOMY
CASE 1
CAVERNOUS SINUS
THROMBOSIS

2. HISTORY
Patient develops a boil on his upper lip after cutting
himself shaving on a hunting trip
He presents to his physician with a high fever and
severe headaches
Patient does not improve with penicillin injections and
is admitted to a hospital
EXAMINATION
Rigidity of neck muscles
Upper lip swollen and oozing pus
Cheek, side of nose and eyelids swollen
Exophthalmos
Edema of optic nerve at papilla
Inability to move eye
Paresthesia of forehead, side of nose and upper cheek
Blood culture positive for Staphylococcus aureus

3. DIAGNOSIS
Staphylococcic infection of upper lip and infectious
cavernous sinus thrombosis
THERAPY AND FURTHER COURSE
Patient is put on intravenous antibiotics
Warm, moist dressings applied to face
Narcotics given for pain
Patient responds slowly to antibiotics and ocular
functions improve only gradually
After three weeks patient has made a complete recovery
and is discharged

4. PATIENT WITH CAVERNOUS SINUS THROMBOSIS

5. Where is the cavernous sinus located?
In the middle cranial fossa adjacent to the body of the sphenoid bone.

6. Cavernous sinus

7. What anatomical features does the cavernous sinus
share with other venous
sinuses and in what respects
does it differ?
2. What anatomical features does the cavernous sinus share with other venous sinuses and in what respects does it differ?
Similarities
a) It is located within the dura.
b) It is lined by endothelium.
c) It is lacking a muscular coat.
d) It lacks valves.
Differences
a) It is traversed by numerous trabeculae (which give it a sponge-like appearance and make it quite liable to thrombosis).
b) III, IV, V1, and V2 are embedded in its lateral wall, while VI and the internal carotid artery (with its sympathetic plexus) course through its lumen.

8. within body of sphenoid bone
Cavernous sinus
Optic chiasm
Hypophysis
Differences from
other sinuses
Similarities with
other sinuses
Within dura
III IV
Int. carotid a.
(w/sympathetic plexus)
Lined by endothelium
Lacks muscular coat VI
Lacks valves V1 V2
Contains
trabeculae
Sphenoid sinuses
within body of sphenoid bone

9. 3a. What are the tributaries to the cavernous sinus?
b. What veins directly drain
3. a) What are the tributaries to the cavernous sinus?
The cavernous sinus receives blood from the superior and inferior ophthalmic veins, central vein of the retina, superficial middle cerebral vein and the sphenoparietal sinus.
b) What veins directly drain the cavernous sinus?
The superior and inferior petrosal sinuses drain the cavernous sinus directly.

10. Tributaries
Cavernous sinus
Sup. ophthalmic v.
Inf. ophthalmic v.
(not shown)
Intercavernous sinus
Central v. of retina
(inside optic n.)
Sphenoparietal
sinus
Superficial
middle cerebral v.
Drainage
Sup. petrosal
sinus
Inf. petrosal
sinus

11. 3c. Into what vein does the blood in the cavernous
sinus ultimately drain?
3. c) Into what vein does the blood in the cavernous sinus ultimately drain?
Ultimately this blood reaches the internal jugular vein which begins at the base of the skull (jugular foramen).

12. Sup. petrosal sinus
Inf. petrosal sinus
Sigmoid sinus
To int. jugular v.

13. 4a. What is the definition of an emissary vein? Can the
ophthalmic veins be
regarded as emissary veins?
b. What is the direction of blood
flow in emissary veins?
c. In view of your answer (to b)
above, what is the clinical
significance of emissary veins?
4.a) What is the definition of an emissary vein? Can the ophthalmic veins be regarded as emissary veins?
Emissary veins are communications between intracranial venous sinuses and extracranial veins. Since the ophthalmic veins connect the cavernous sinus with the upper end of the facial vein (termed the angular vein) they can be considered emissary veins.
b) What is the direction of blood flow in emissary veins?
Because they are valveless, blood may flow in either direction (i.e., outside to inside or vice versa).
c) In view of your answer (to b) above, what is the clinical significance of emissary veins?
1) They provide routes for infection to spread into the cranial cavity.
2) They act as a safety mechanism when there is an increase in intracranial venous pressure that might otherwise endanger the brain.

14. Angular v.
Sup. ophthalmic v.
Cavernous sinus
Facial v.
Inf. ophthalmic v.

15. Describe the venous pathway by which infectious material
reached the cavernous sinus
in this patient.
5. Describe the venous pathway by which infectious material reached the cavernous sinus in this patient.
The infection spread from the superior labial vein (upper lip) to the facial vein. From here it passed in retrograde fashion (facial vein has no valves) to the ophthalmic veins. The infection then passed posteriorly through the ophthalmic veins into the cavernous sinus. (Note: Squeezing of the boil by the patient and the never-ceasing motion of the labial muscles tended to “milk” the infectious material along these venous channels).

16. Sup. ophthalmic v.
Angular v.
Facial v.
Sup. labial v.

17. swelling of the eyelids and conjunctivae, the exophthalmos,
6. How do you explain the
swelling of the eyelids and
conjunctivae, the exophthalmos,
the dilation of the retinal veins
and the edema of the optic nerve
in this patient?
6. How do you explain the swelling of the eyelids and conjunctivae, the exophthalmos, the dilation of the retinal veins and the edema of the optic nerve in this patient?
All these signs are caused by interference with the blood flow in the cavernous sinus and ophthalmic veins due to the thrombosis (clotting). The latter causes retrograde congestion of the orbital veins and edema (swelling) of the orbital structures.

18. Retinal v.
Optic n.
Central v. of retina

19. Optic disc
(papilla)

20. What cranial nerves have been affected by this infectious
thrombosis? (Give reasons for
your answers). Through what
openings do these nerves leave
the cranial cavity?
7. What cranial nerves have been affected by this infectious thrombosis? (Give reasons for your answers.) Through what openings do these nerves leave the cranial cavity?
II (optic canal)—Impairment of vision due to edema of the nerve.
III, IV, and VI (superior orbital fissure)—All voluntary movements produced by the extraocular muscles are abolished. (Note: Mnemonic for remembering innervation of extraocular muscles is SO4(LR6)R3—Superior Oblique IV, Lateral Rectus VI, Remaining muscles III.)
V1 (superior orbital fissure)—Paresthesia of forehead (area of skin supplied by V1).
V2 (foramen rotundum)—Paresthesia of side of nose and upper cheek (area of skin supplied by V2).

21. SO4, LR6, R3 Levator palpebrae superioris m. Sup. oblique m.
Sup. rectus m.
III IV VI
Inf. rectus m.
Inf. oblique m.
Med. rectus m.
Lat. rectus m.

22. Ophthalmic n. (V1)
Maxillary n. (V2)
Mandibular n. (V3)

23. Optic canal
(II)
Sup. orbital fissure
(III, IV, VI, V1)
F. rotundum
(V2)

24. What might be the consequence if the infectious material invaded
the internal carotid artery within
the sinus?
8. What might be the consequence if infectious material invaded the internal carotid artery within the sinus?
The infection could spread to the brain by means of its anterior and middle cerebral branches.
(Note: retrograde spread of infection via the superficial middle cerebral vein could also lead to brain infection.)

25. Mid. cerebral a.
Ant. cerebral a.
Cavernous sinus
containing ICA

26. Ant. cerebral a.
Ant. communicating a.
ICA
Mid. cerebral a.
Post. communicating a.
Post. cerebral a.
Basilar a.
Vertebral a.

27. Superficial middle
cerebral v.

28. 9. Explain how osteomyelitis (inflamation of the bone and
marrow) of the upper or lower
jaw following tooth extraction
could lead to infectious cavernous
sinus thrombosis. (Hint: What
important venous structure lies
in the infratemporal fossa?)
9. Explain how osteomyelitis (inflamation of the bone and marrow) of the upper or lower jaw following tooth extraction could lead to infectious cavernous sinus thrombosis. (Hint: What important venous structure lies in the infratemporal fossa?)
The upper and lower jaws and their teeth are drained by the superior and inferior alveolar veins which are tributaries (directly or indirectly) to the pterygoid venous plexus. This plexus lies in the infratemporal fossa and communicates with the cavernous sinus via an emissary vein passing through the foramen ovale. Infection could therefore spread from the jaws to the pterygoid plexus and then into the cavernous sinus via this emissary vein.

29. Emissary v. connecting
w/ cavernous sinus via
f. ovale
Post. sup. alveolar v.
Pterygoid plexus of vv.
Inf. alveolar v.

30. Additional Note
Infectious cavernous sinus thrombosis was almost invariably fatal
prior to the advent of antibiotics. In this era of intensive antibiotic
treatment the condition is not as common as it used to be but the
prognosis, should one contract it, is grim —
80% mortality and in the survivors 75% after effects, mainly involving
eye muscles and changes in visual acuity.

31. END