What is the medical term for blood flow to the ear?

Medical Term for Blood Flow to the Ear

The medical term for blood flow to the ear is "otic circulation" or more specifically "cochlear blood flow" when referring to the inner ear circulation.

Anatomy of Ear Blood Supply

The ear's blood supply is anatomically divided according to the three main parts of the ear:

1. External Ear

   • Supplied primarily by branches of the external carotid artery
   • The auricle (pinna) receives blood from the posterior auricular and superficial temporal arteries

2. Middle Ear

   • Receives blood primarily from branches of the maxillary artery (anterior tympanic artery)
   • Additional supply from the stylomastoid branch of the posterior auricular artery
   • The middle ear cavity requires adequate blood flow to maintain proper function of the tympanic membrane and ossicles

3. Inner Ear

   • Supplied by the labyrinthine artery (also called inner ear artery)
   • This is usually a branch of the anterior inferior cerebellar artery (AICA)
   • The cochlea receives its dedicated blood supply through the cochlear branch
   • This circulation is critical for maintaining the blood-labyrinth barrier and proper hearing function 1

Clinical Significance

Understanding ear blood flow is important in several clinical contexts:

• Sudden Sensorineural Hearing Loss: Often theorized to involve cochlear blood flow disturbances 2
• Ménière's Disease: May involve vascular dysfunction in the inner ear 3
• Noise-induced Hearing Loss: Potentially related to alterations in cochlear blood flow 1
• Presbycusis (age-related hearing loss): May involve vascular changes in the cochlea 1

Vascular Pathophysiology

The inner ear vasculature serves several critical functions:

• Maintenance of the blood-labyrinth barrier
• Transport of systemic hormones for ion homeostasis
• Supply of nutrients for metabolic functions 4

Cochlear blood flow is determined by cochlear perfusion pressure, which is calculated as the difference between mean arterial blood pressure and inner ear fluid pressure 1.

Diagnostic Approaches

When investigating potential vascular causes of hearing disorders, several techniques may be used:

• Magnetic resonance imaging
• Laser-Doppler flowmetry
• Ultrasonography 1

Therapeutic Implications

Vasodilating agents have been studied for their effects on cochlear blood flow, with varying results:

• Sodium nitroprusside applied topically to the round window membrane has shown the most effectiveness in increasing cochlear blood flow
• Hydralazine and histamine also show some benefit when applied topically
• Systemic administration of vasodilators often causes a decrease in blood pressure that may limit their effectiveness in the cochlea 3

However, clinical practice guidelines from the American Academy of Otolaryngology—Head and Neck Surgery recommend against routine use of vasodilators or vasoactive substances for sudden sensorineural hearing loss due to lack of proven efficacy and potential side effects 5.

Vascular Classification of Inner Ear Disorders

A classification system for inner ear ischemia has been proposed:

• Type I: Involves only cochlear vessels, resulting in hearing loss without vertigo
• Type II: Involves part of the cochlea and part of the vestibular system
• Type III: Involves only the vestibular system
• Type IV: Complete absence of blood circulation in the inner ear, resulting in total deafness and severe vertigo 6

Understanding the specific vascular pathways in the ear helps clinicians better diagnose and potentially treat various forms of hearing loss and balance disorders.