THE EAR

The anatomy and physiology of the ear are summarized in Figure 16.1.

Hearing loss

Hearing loss is a common problem that affects many people, at least on a temporary basis. Short-lived hearing loss occurs when flying or during an ear infection. In contrast, permanent sensorineural hearing loss often occurs with ageing. Deafness can be conductive or sensorineural, and these are differ-entiated at the bedside by the Rinne and the Weber tests (see below). Con-ductive hearing loss is due to an abnormality of the outer or middle ear. The outer ear is examined with an auroscope which may show wax or a foreign body in the external canal or abnormalities of the tympanic membrane such as perforation or loss of the normal light reflex. Sensorineural hearing loss is due to a disorder of the inner ear, cochlea, or the cochlear nerve (Table 16.1).

An ear that hears normally should have air conduction that is louder than bone conduction. The Rinne test allows comparison of sound when a vibrating tuning fork, 512 Hz, is placed on the mastoid bone behind the ear (bone conduction) versus when the tuning fork is held next to the ear (air conduc-tion). The Rinne test is normal (positive) when the tuning fork is louder if held next to the ear compared to being placed on the mastoid bone. The opposite is the case in a negative test. The Weber test is performed by placing the handle of the vibrating tuning fork on the bridge of the nose and asking the patient if the sound is louder in one ear or the other. The sound is heard equally in patients with normal hearing or with symmetrical hearing loss.

Fig. 16.1 Anatomy and physiology of the ear. Sound waves are transmitted to the fluid-filled cochlea via the external auditory canal, tympanic membrane (the ear drum) and bony ossicles (stapes, incus, malleus). Hair cells in the basilar membrane of the cochlea detect the vibrations and transduce into nerve impulses which pass via the cochlear nerve (part of 8th cranial, vestibulocochlear, nerve) to the cochlear nucleus in the brainstem and then to the superior olivary nuclei. The vestibular nerve carries information from the semicircular canals about balance. The middle ear is normally filled with air and communicates with mastoid air cells superiorly, and nasopharynx medially via the Eustachian tube. The latter functions as a pressure-equalizing valve for the middle ear and opens for a fraction of a second periodically in response to swallowing or yawning. Anything that interferes with this periodic opening and closing or blocks the Eustachian tube may result in hearing impairment or other ear symptoms.

Vertigo

The vestibular apparatus in the inner ear comprises two components: the semicircular canals, which indicate rotational movements and the otoliths (urticle and saccule) which sense linear acceleration. These organs provide information to the brainstem (via the vestibular part of 8th cranial nerve) and cerebellum regarding the static head position and turning of the head. Vertigo is an illusion of movement, i.e. that everything is spinning or moving, and can arise from peripheral lesions (disorders of the vestibular apparatus or vestibular nerve) or central lesions (of the brainstem or cerebellum).

Benign paroxysmal positional vertigo accounts for about half of cases with peripheral vestibular dysfunction. Calcium debris in one of the semicir-cular canals leads to recurrent episodes of vertigo lasting seconds to minutes. Episodes are provoked by specific types of head movements, e.g. turning in bed or sitting up. There is no serious underlying cause and the condition may resolve spontaneously.

Vestibular neuronitis is believed to be caused by a viral infection affect-ing the labyrinth. There is a sudden onset of severe vertigo, nystagmus and vomiting, but no deafness. The attack lasts several days or weeks, and treat-ment is symptomatic with vestibular sedatives (e.g. prochlorperazine).

Ménière’s disease is due to a build-up of endolymphatic fluid in the inner ear. It is characterized by recurrent episodes of vertigo lasting 30 minutes to a few hours. It is associated with a sensation of ear fullness, sensorineural hearing loss, tinnitus and vomiting. Treatment involves the use of vestibular sedatives, e.g. cinnarizine in the acute phase, low-salt diet, betahistine, and avoidance of caffeine.

Central causes of vertigo are often vascular and may also be due to multiple sclerosis or drug-induced (e.g. anticonvulsants, alcohol or hypnotics).

Ear infections

Otitis externa is a diffuse infection (bacterial, viral or fungal) of the skin of the ear canal. There is severe pain and on examination debris in the ear canal sometimes with swelling. Treatment is with regular cleansing, topical antibiotics and corticosteroids. Otitis media is inflammation of the middle ear, usually due to a viral infection. There is severe pain, conductive hearing loss and a mucous discharge if the eardrum is perforated. Antibiotic treatment, amoxicillin 1 g every 8 hours for 5 days, is indicated if there are systemic features or if symptoms do not settle within 72 hours. Swelling and tender-ness over the mastoid bone indicate mastoiditis and is an indication for an urgent ENT opinion.

Ebook Essentials of Kumar and Clark's Clinical Medicine, 5e

1. Ethics and communication

Ethics and communication

2. Infectious diseases

Infectious diseases

3. Gastroenterology and nutrition

Gastroenterology and nutrition

4. Liver, biliary tract and pancreatic disease

Liver, biliary tract and pancreatic disease
LIVER BIOCHEMISTRY AND LIVER FUNCTION TESTS
SYMPTOMS AND SIGNS OF LIVER DISEASE
JAUNDICE
HEPATITIS
NON - ALCOHOLIC FATTY LIVER DISEASE (NAFLD)
CIRRHOSIS
COMPLICATIONS AND EFFECTS OF CIRRHOSIS
LIVER TRANSPLANTATION
TYPES OF CHRONIC LIVER DISEASE AND CIRRHOSIS
PRIMARY SCLEROSING CHOLANGITIS
BUDD - CHIARI SYNDROME
LIVER ABSCESS
LIVER DISEASE IN PREGNANCY
LIVER TUMOURS
GALLSTONES
THE PANCREAS
CARCINOMA OF THE PANCREAS
NEUROENDOCRINE TUMOURS OF THE PANCREAS

5. Haematological disease

Haematological disease
ANAEMIA
Assessment and treatment of suspected neutropenic sepsis
HAEMOLYTIC ANAEMIA
INHERITED HAEMOLYTIC ANAEMIAS
ACQUIRED HAEMOLYTIC ANAEMIA
MYELOPROLIFERATIVE DISORDERS
THE SPLEEN
BLOOD TRANSFUSION
THE WHITE CELL
HAEMOSTASIS AND THROMBOSIS
THROMBOSIS
THERAPEUTICS

6. Malignant disease

Malignant disease
MYELOABLATIVE THERAPY AND HAEMOPOIETIC STEM CELL TRANSPLANTATION
THE LYMPHOMAS
THE PARAPROTEINAEMIAS
PALLIATIVE MEDICINE AND SYMPTOM CONTROL

7. Rheumatology

Rheumatology
COMMON INVESTIGATIONS IN MUSCULOSKELETAL DISEASE
COMMON REGIONAL MUSCULOSKELETAL PROBLEMS
BACK PAIN
OSTEOARTHRITIS
INFLAMMATORY ARTHRITIS
THE SERONEGATIVE SPONDYLOARTHROPATHIES
Clinical features, Investigations
INFECTION OF JOINTS AND BONES
AUTOIMMUNE RHEUMATIC DISEASES
SYSTEMIC INFLAMMATORY VASCULITIS
DISEASES OF BONE
THERAPEUTICS

8. Water, electrolytes and acid–base balance

WATER AND ELECTROLYTE REQUIREMENTS
BODY FLUID COMPARTMENTS
REGULATION OF BODY FLUID HOMEOSTASIS
PLASMA OSMOLALITY AND DISORDERS OF SODIUM REGULATION
DISORDERS OF POTASSIUM REGULATION
DISORDERS OF MAGNESIUM REGULATION
DISORDERS OF ACID - BASE BALANCE
THERAPEUTICS

9. Renal disease

Renal disease
INVESTIGATION OF RENAL DISEASE
GLOMERULAR DISEASES
NEPHROTIC SYNDROME
URINARY TRACT INFECTION
TUBULOINTERSTITIAL NEPHRITIS
HYPERTENSION AND THE KIDNEY
RENAL CALCULI AND NEPHROCALCINOSIS
URINARY TRACT OBSTRUCTION
ACUTE RENAL FAILURE/ACUTE KIDNEY INJURY
CHRONIC KIDNEY DISEASE
RENAL REPLACEMENT THERAPY
CYSTIC RENAL DISEASE
TUMOURS OF THE KIDNEY AND GENITOURINARY TRACT
DISEASES OF THE PROSTATE GLAND
TESTICULAR TUMOUR
URINARY INCONTINENCE

10. Cardiovascular disease

COMMON PRESENTING SYMPTOMS OF HEART DISEASE
INVESTIGATIONS IN CARDIAC DISEASE
CARDIAC ARRHYTHMIAS
HEART FAILURE
ISCHAEMIC HEART DISEASE
RHEUMATIC FEVER
VALVULAR HEART DISEASE
PULMONARY HEART DISEASE
MYOCARDIAL DISEASE
CARDIOMYOPATHY
PERICARDIAL DISEASE
SYSTEMIC HYPERTENSION
ARTERIAL AND VENOUS DISEASE
ELECTRICAL CARDIOVERSION
DRUGS FOR ARRHYTHMIAS
DRUGS FOR HEART FAILURE
DRUGS AFFECTING THE RENIN - ANGIOTENSIN SYSTEM
NITRATES, CALCIUM - CHANNEL BLOCKERS AND POTASSIUM - CHANNEL ACTIVATORS

11. Respiratory disease


Respiratory disease
TUBERCULOSISnd
DIFFUSE DISEASES OF THE LUNG PARENCHYMA
OCCUPATIONAL LUNG DISEASE
CARCINOMA OF THE LUNG
DISEASES OF THE CHEST WALL AND PLEURA
DISORDERS OF THE DIAPHRAGM

12. Intensive care medicine

Intensive care medicine

13. Drug therapy, poisoning, and alcohol misuse

Drug therapy, poisoning, and alcohol misuse

14. Endocrine disease

Endocrine disease
PITUITARY HYPERSECRETION SYNDROMES
THE THYROID AXIS
MALE REPRODUCTION AND SEX
FEMALE REPRODUCTION AND SEX
THE GLUCOCORTICOID AXIS
THE THIRST AXIS
DISORDERS OF CALCIUM METABOLISM
DISORDERS OF PHOSPHATE CONCENTRATION
ENDOCRINOLOGY OF BLOOD PRESSURE CONTROL
DISORDERS OF TEMPERATURE REGULATION
THERAPEUTICS

15. Diabetes mellitus and other disorders of metabolism

DIABETES MELLITUS
DIABETIC METABOLIC EMERGENCIES
COMPLICATIONS OF DIABETES
SPECIAL SITUATIONS
HYPOGLYCAEMIA IN THE NON - DIABETIC
DISORDERS OF LIPID METABOLISM
THE PORPHYRIAS

16. The special senses

THE EAR
THE NOSE AND NASAL CAVITY
THE THROAT
THE EYE

17. Neurology

COMMON NEUROLOGICAL SYMPTOMS
COORDINATION OF MOVEMENT
THE CRANIAL NERVES
COMMON INVESTIGATIONS IN NEUROLOGICAL DISEASE
UNCONSCIOUSNESS AND COMA
STROKE AND CEREBROVASCULAR DISEASE
EPILEPSY AND LOSS OF CONSCIOUSNESS
NERVOUS SYSTEM INFECTION AND INFLAMMATION
HYDROCEPHALUS
HEADACHE, MIGRAINE AND FACIAL PAIN
SPINAL CORD DISEASE
DEGENERATIVE NEURONAL DISEASES
DISEASES OF THE PERIPHERAL NERVES
MUSCLE DISEASES
MYOTONIAS
DELIRIUM
THERAPEUTICS

18. Dermatology

Dermatology

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