Otitis Media Flashcards
what is used to examine the ear?
otoscope
what can be seen via an otoscope?
the tympanic membrane and the bones specifically the malleus
what is Otitis media?
inflammation or infection of the middle ear, that is associated with a collection of fluid (effusion).
There is a spectrum of disease from mild and reversible to chronic and destructive.
what are the typical clinical features for a middle ear infection In infants?
75% of children have had at least one episode by the age of 3 years.
Clinical features may include:
Otalgia (earache) manifest by pulling or rubbing ear
Decreased hearing
Non-specific symptoms may include:
Fever (pyrexia), vomiting, irritability, often tugging at ear, and poor feeding
what is a common bacteria responsible for otitis media?
streptococcus pneumonia
what is the shape and arrangement of streptococcus pneumonia?
gram positive cocci in chain
what bacteria would you stain as a control to contrast with streptococcus pneumonia?
e.coli (negative)
S. aeuresu (positive)
what is sensorineural hearing loss?
due to disease of the cochlea, the organ of Corti, CN VIII or more central neural pathways and connections
what is conductive ear loss?
resulting from failure of the conducting mechanisms of the outer and middle ear to transmit sound to the fluids of the inner ear
how are air signals converted into electrical signals in the brain?
Sound waves are collected by the pinna and travel down the ear canal.
The tympanic membrane is stretched across the end of the external auditory canal and air molecules vibrate at the same frequency as the sound wave.
These vibrations are transmitted and amplified through the ossicles – malleus, incus and stapes – to the oval window. The total force of a sound wave applied to the tympanic membrane is transferred to the oval window but, because the oval window is so much smaller, the force per unit area (ie pressure) is increased 15 to 20 times.
Vibration of the oval window is transmitted into the scala vestibuli and then into the scala media (aka cochlear duct). Pressure waves across the cochlear duct cause the basilar membrane to vibrate where the Organ of Corti is located.
The hair cells are mechanoreceptors with stereocilia that are stimulated by movement of the basilar membrane relative to the tectorial membrane. The stereocilia bend which results in opening of ion channels in the plasma membrane of the hair cell, depolarising the membrane and creating a receptor potential. Hair cells release an excitatory neurotransmitter when depolarised, which leads to excitation of cochlear afferent neurons, which make up the nerve fibres of the cochlear nerve.
what enzyme does paracetamol inhibit?
COX (Cyclooxygenase) enzyme
what is the mechanism of action of amoxicillin?
Amoxicillin inhibits cell wall synthesis in the bacteria, resulting in death of the bacteria
