The blood supply received by the cochlea. Broadly responsible for electromotility of hearing cells.

1. Blood Supply to Cochlea
Ankita. H. More
Roll No. 3
M.Sc. Audiology Semester 1.

2. • Normal blood supply to cochlea is crucial for
auditory transduction .
• The vascularization of inner ear is
independent from that of otic capsule and
tympanic cavity.
• Extensive studies have found widespread
similarities in the vascular anatomy of cochlea
among various mammalian species, including
humans

4. Blood supply to the ear (in short)
• The blood supply of the ear differs according to each part of the ear.
• The outer ear is supplied by a number of arteries namely,
The posterior auricular artery which provides the majority of the blood
supply. The anterior auricular arteries provide some supply to the outer
rim of the ear and scalp behind it. The posterior auricular artery is a
direct branch of the external carotid artery, and the anterior auricular
arteries are branches from the superficial temporal artery.
• The middle ear is supplied by the mastoid branch of either
the occipital or posterior auricular arteries and the deep auricular artery,
a branch of the maxillary artery. Other arteries which are present but
play a smaller role are the branches of the middle meningeal
artery, ascending pharyngeal artery, internal carotid artery, and the
artery of the pterygoid canal.
• The inner ear is supplied by the labyrinthine artery, arising from either
the anterior inferior cerebellar artery, a branch of the basilar artery.

5. Basiliar Artery in the brain
Basiliar Artery branches

6. • The basilar artery is part of the blood supply system for
the brain and central nervous system. It is formed
where the two vertebral arteries join at the base of the
skull.
• Usually a few millimeters below the Ponto- medullary
junction, the two vertebral arteries join to form the
basilar artery .
• An extensive distribution of basilar artery within the
brainstem provides the blood supply to many of the
auditory structures
• Basilar artery gives rise to the labyrinthine /
internal auditory artery in two possible ways i.e:
1. Either it branches directly from the basilar artery.
2. It arises from anterior inferior cerebellar
artery(AICA).

7. A brief overview of
the anatomy of cochlea

9. Basilar artery
Internal auditory artery
Common cochlear artery Anterior vestibular artery
Spiral modiolar
artery
Vestibulo- cochlear
artery
½ turn of
basal end
to apex
Cochlear
branch
¼ - ½th basal
turn of
cochlea
Vestibular
branch
Basal end of
cochlea
Vestibule
Utricle
Small portion of
saccule
Ampulla of
superior and
Horizontal SSC

11. LABYRITHINE ARTERY
A branch of the Anterior Inferior Cerebellar Artery.
Principally supplies the labyrinth.
- Origin: Basiliar or the Vertebral Artery
- Course: Passes down the Internal Auditory Meatus
(IAM) to divide into
Anterior-Vestibular Artery (AVA) and Common
Cochlear Artery (CCA). CCA passes further down into the
Internal Auditory Meatus and divides into two more
branches viz Cochlear Artery and Vestibulocochlear Artery
(VcA).

12. • Which parts do the two arteries supply?
a) The ANTERIOR VESTIBULAR ARTERY supplies the
-Vestibular Nerve (CN VIII branch)
- Major part of the Utricle
- parts of the Semicircular ducts (Canals)
b) The VESTIBULOCOCHLEAR ARTERY is further
divided into two terminal branches viz. Vestibular
and Cochlear branches which take opposite
directions in the basal turn of the cochlea.

13. *Vestibular branch supplies the
- Saccule
- Greater part of the Semicircular Canals
- Basal end of the cochlea
- Cochlear capillary areas in the spiral ganglion
- Osseous spiral lamina
* Cochlear branch supplies the
- cochlear regions
• Both Vestibular and Cochlear branches supply the
-Cochlear capillary areas in the spiral ganglion
- Osseous spiral lamina
-limbus (Look it up)
-spinal ligament

14. • The cochlea is drained by the Spiral modiolar
vein, which originates as the venules from
the capillary regions in the apical turn and
descends in spiral course from the apex to
the base in the bone at lower medial corner
of scala tympani.
• Both the Vestibular and Cochlear branches of
AVA eventually form arterioles that end up in
capillary networks in the spiral lamina or the
stria vascularis on the lateral wall of the
cochlear duct.
• These capillaries drain into venules that run
under the floor of the scala tympani

15. Vein of cochlear aqueduct
Jugular vein
Vestbulo cochlear vein
Ant. Vestibular
Vein
Post.
Vestibular
Vein
Vein of
round
window
Common modiolar vein
Vein of Scala
tympani
Vein of Scala
vestibuli
Spiral
ganglion
Ext. wall
of SM &
ST
Spiral
lamina
Whole
cochlea
¼ basal
turn of
cochlea
Posterior
SCC
Saccule
Sup. and
Hori. SCC
Utricle

16. • Anterior Spiral Vein- Made up of venules that
drain into the apical region of the modiolos.
• Posterior Spinal Vein- Made up of venules that
drain into the basal region of the modiolos.
• The above two veins join in the basal turn of
cochlea. The Vein of Cochlear Aqueduct- a
principal vein of cochlea. The Vein of Cochlear
Aqueduct empties in the jugular bulb.

17. • The Vestibular labyrinth is drained from the
Anterior part of the Anterior Vestibular Vein
(AVV). This becomes the Labyrinthine Vein
(LV). The LA and LV usually end in the superior
petrosal sinus and also a posterior part of the
same vein which passes alongside the
endolymphatic duct to the sigmoid sinus.

18. Vascular anatomy of the External wall of the
membranous cochlea.
• Vasculature in External wall of membranous cochlea:
-External wall of Scala vestibuli
-External wall of Scala media
-External wall of Scala tympani
• External wall of Scala vestibuli
-Radiating arterioles
-Collecting venules
-Vessels of the Vestibular membrane
-Capillary net above the Vestibular membrane
• External wall of Scala media
-Stria vascularis
-Vessel of Spiral prominance
- Arterio venous anastomoses

19. Variations in cochlear vessels depending
on location
• Cochlear vascularization decreases from base to
apex in all species.
• In Humans, greater portion of base is supplied by
the vein of cochlear aqueduct.
• The capillary net of the stria vascularis is narrow in
the region between the round and oval windows in
all species.

20. THE COURSE OF BLOOD SUPPLY
CCA
LA
AVA
ChA
VCA
Vestibular
Cochlear
CAq
JB
AVA/LV
SS SPS
ALA+PLA
ALA+PLA

21. Complications due to improper blood
supply to cochlea
• Many otologic disorders such as noise-induced hearing loss,
endolymphatic hydrops and presbycusis are suspected of
being related to alterations in cochlear blood flow.
• Obstruction of spiral modiolar artery would be expected to
cause hearing loss predominating in the low frequency.
• Obstruction in the Vestibulo cochlear artery would be
expected to cause hearing loss predominating in the High
frequency and accompanied with Vertigo.
• Abrupt sensorineural hearing loss associated with slow blood
flow in the vertebro basilar system in human.
• Typical Ischemia related hearing loss occurs after ponto-
cerebellar surgery with preservation of the auditory nerve
and cochlea.

22. • Disorders due to compression of the vessels: Due to
induced or naturally occuring compression- Reduced
blood flow to the inner ear infrequently manifests with
sudden hearing loss, either by directly affecting hair
cells and/or stria vascularis or the VIII th nerve.
Conductive deafness due to pathologies of the
neighboring vessels has also been reported.
• Arterial loops of AICA compress the VIIIth nerve on
occasions, causing typical cerebellopontine angle (CPA)
mass findings with the signs and symptoms of
sensorineural hearing loss (SNHL) of retro-cochlear
origin. Pulsatile tinnitus is also reported to be one of
the hallmarks of this anatomic variation. Ectatic
vertebral and basilar artery has been shown to mimic
CPA tumors, Méniere’s disease and other peripheral or
central conditions with inner ear symptoms, by
compressing brainstem and the VIIIth nerve

23. • Aneurysm of AICA may also cause sudden hearing loss, although it
is extremely rare.
• High jugular fossa is usually seen on the right side, encroaches
upon labyrinth, effects cochlear aqueduct, vestibular aqueduct
and erodes posterior semicircular canal. It typically causes low
frequency SNHL as well as occasional conductive hearing loss.
Greatly enlarged jugular fossa is also situated higher than normal
level and accompanied by a giant sigmoid sinus and sometimes
with a diverticulum. Symptomatology and aetiopathogenesis is
very similar to those of high jugular fossa. In addition, giant jugular
fossa may affect cochlear circulation by causing turbulent flow and
decreased venous return.
• Infarction of internal auditory artery: Isolated infraction of internal
auditory artery has also been reported with the histopathologic
correlates of degeneration in the vestibulecochlear nerve.
• Susac’s syndrome is an idiopathic disorder characterized by the
triad of encephalopathy, fluctuating hearing loss, and visual loss
resulting from microangiopathy of the brain, cochlea, and retina.

24. • Vascular tumors cause conductive hearing loss at early
stages and may invade labyrinth, causing SNHL.
• Thrombosis of AICA affects almost all the structures in
the brainstem, including auditory pathways and nuclei
at varying degrees as well as the VIIIth nerve and
labyrinth itself. Some cases of AICA infarction may also
present with recurrent symptoms that mimic Méniere’s
disease.
• Vertebro-basilar ischemia is usually caused by
atherosclerosis and may lead to sudden hearing loss by
labyrinthine infarction with accompanying vertigo that
could be bilateral. Although very rarely, infarction in the
territory of PICA may also be associated with audio-
vestibular symptoms.

25. • There is a well established correlation between SNHL
and systemic cardiovascular diseases.
• Vertebral giant cell arteritis effects whole vertebro-
basilar system including labyrinthine artery, presenting
with Méniere-like symptoms.
• Diabetes mellitus may cause low frequency hearing
loss.
• Common systemic cardio-vascular diseases: Coronary
heart disease, intermittent claudicatio and systemic
hypertension are all associated with SNHL especially in
elderly patients. The cochlear ageing is accelerated in
these cases. stress, hyperlipidemia, glucose intolerance,
renal apparatus and even gastroenteric diseases with a
functional component can attribute to the
development of hearing loss by constituting risk factors
for systemic cardio-vascular diseases and/or
hemodynamic imbalance.

26. • Systemic vasculitis usually causes sudden or progressive SNHL or
mixed hearing loss by predisposing different forms of otitis media
as well (63). Once they affect the inner ear, the damage is usually
grave and irreversible. Long-standing systemic arteriolar
insufficiencies tend to cause low frequency hearing loss,
presumably due to resultant strial atrophy.
• Wegener’s granulomatosis: Commonly causes otitis media with
effusion (35-47%), sometimes with chronic granulomatous
changes in the middle ear. It may also cause cochlear damage and
VIII th nerve damage by directly affecting their arterioles through
necrotizing vasculitis.
• Cogan’s syndrome: Active vasculitis and fibrosis of the medium
and small arteries are typical of this immune-mediated idiopathic
disease. Audio-vestibular system is frequently involved with
associated vertigo, tinnitus and hearing loss.
• Other cases that show hearing disorders due to faulty blood supply
are Systemic lupus erythematosis (SLE), Polyarteritis nodosa (PAN),
Tromboangitis obliterans and Systemic sclerosis (Scleroderma)

27. • Yamasoba et al found an association between the
sudden hearing loss and slow blood flow within the
vertebro-basilar system. Hypoventilation has also been
shown to be associated with the concurrent decrease in
the CBF. Cochlea is also found more susceptible to
ischemia than the VIIIth nerve.
• Increased blood viscosity also well correlate with
hearing loss, adversely effecting RBC velocity and
cochlear oxygenation.
• Decreased RBC deformability is characteristics of blood
dyscrasia such as thalassemia and sickle cell anemia
and associated with cochlear hearing loss.
• Noise at non-physiological or potentially damaging
levels, either continuous or intermittent, can produce
constrictive effects on cochlear vessels, thus reducing
CBF

28. References
• Pictures from Google
• Scott-brown, S.B. (1987). Anatomy and Ultrasound of the
human ear. In Kerr, A. .G & Wright, D (Eds), Scott-Brown's
Otolaryngology (pp. 42). London: Butterworth and Co.
• Ear. (c2020). Ear. Retrieved 9 March, 2021, from
https://en.wikipedia.org/w/index.php?title=Ear&action=histo
ry
• Nakashima T, Naganawa S, Sone M, Tominaga M, Hayashi H,
Yamamoto H, Liu X, Nuttall AL. Disorders of cochlear blood
flow. Brain Res Brain Res Rev. 2003 Sep;43(1):17-28. doi:
10.1016/s0165-0173(03)00189-9. PMID: 14499459.
• Yıldırım , N. (2012). Hearing Impairment in Vascular
Disorders. Van Medical Journal, 19(3), 149-157