A summary of the diagnostic strategy model is presented in TABLE 46.2.
Table 46.2Dizziness/vertigo: diagnostic strategy model |Favorite Table|Download (.pdf) Table 46.2 Dizziness/vertigo: diagnostic strategy model
Postural hypotension (G/S)
Simple faint—vasovagal (S)
Acute vestibulopathy (V)
Benign paroxysmal positional vertigo (V)
Motion sickness (V)
Vestibular migraine (V)
Serious disorders not to be missed
Intracerebral infection (e.g. abscess)
Carbon monoxide poisoning
Pitfalls (often missed)
Alcohol and other drugs
Cough or micturition syncope
Vestibular migraine/migrainous vertigo
Ménière syndrome (overdiagnosed)
Seven masquerades checklist
Diabetes (possible: hypo/hyper)
Thyroid disorder (possible)
Is the patient trying to tell me something?
Very likely. Consider anxiety and/or depression.
In medical school we gain the wrong impression that the common causes of dizziness or vertigo are the relatively uncommon causes, such as Ménière syndrome, aortic stenosis, Stokes–Adams attacks, cerebellar disorders, vertebrobasilar disease and hypertension. In the real world of medicine, one is impressed by how often dizziness is caused by relatively common benign conditions, such as hyperventilation associated with anxiety, simple syncope, postural hypotension due to drugs and old age, inner ear infections, wax in the ears, post head injury, motion sickness and alcohol intoxication. In most instances making the correct diagnosis (which, as ever, is based on a careful history) is straightforward, but finding the underlying cause of true vertigo can be very difficult.
The common causes of vertigo seen in general practice are benign paroxysmal positional vertigo (BPPV, so often related to cervical vertebral dysfunction), accounting for about 25% of cases, acute vestibulopathy (vestibular neuronitis) and vestibular migraine.
Viral labyrinthitis is basically the same as vestibular neuronitis, except that the whole of the inner ear is involved so that deafness and tinnitus arise simultaneously with severe vertigo. The most common causes of recurrent spontaneous vertigo are Ménière syndrome and vestibular migraine.
Serious disorders not to be missed
The important serious disorders to keep in mind are space-occupying tumours, such as acoustic neuroma, medulloblastoma and other tumours (especially posterior fossa tumours) capable of causing vertigo, intracerebral infections and cardiovascular abnormalities.
It is important to bear in mind that the commonest brain tumour is a metastatic deposit from lung cancer.3
Red flags for dizziness/vertigo
ataxia out of proportion to vertigo
nystagmus out of proportion to vertigo
central eye movement abnormalities
This uncommon tumour should be suspected in the patient presenting with the symptoms shown in the diagnostic triad below. Headache may occasionally be present.
DxT (unilateral) tinnitus + hearing loss + unsteady gait ➜ acoustic neuroma
Diagnosis is best clinched by high-resolution MRI. Audiometry and auditory evoked responses are also relevant investigations.
Cardiac disorders that must be excluded for giddiness or syncope are the various arrhythmias, such as Stokes–Adams attacks caused by complete heart block, aortic stenosis and myocardial infarction.
The outstanding cerebrovascular causes of severe vertigo are vertebrobasilar insufficiency and brain stem infarction. Vertigo is the commonest symptom of transient cerebral ischaemic attacks in the vertebrobasilar distribution.1
Severe vertigo, often in association with hiccoughs and dysphagia, is a feature of the variety of brain stem infarctions known as the lateral medullary syndrome due to posterior inferior cerebellar artery (PICA) thrombosis. There is a dramatic onset of vertigo with cerebellar signs, including ataxia and vomiting. There are ipsilateral cranial nerve (brain stem) signs with contralateral spinothalamic sensory loss of the face and body. Diagnosis is by CT or MRI scanning.
Important neurological causes of dizziness are multiple sclerosis and complex partial seizures.
The lesions of multiple sclerosis may occur in the brain stem or cerebellum. Young patients who present with a sudden onset of vertigo with ‘jiggly’ vision but without auditory symptoms should be considered as having multiple sclerosis. Five per cent of cases of multiple sclerosis present with vertigo.
A list of conditions causing dizziness that may be misdiagnosed is presented in TABLE 46.2. Wax in the ear certainly causes dizziness, though its mechanism of action is controversial. Cough and micturition syncope do occur, although they are uncommon.
Ménière syndrome is a pitfall in the sense that it tends to be overdiagnosed.
Seven masquerades checklist
Of these conditions, drugs and vertebral dysfunction (of the cervical spine) stand out as important causes. Depression demands attention because of the possible association of anxiety and hyperventilation.
Diabetes mellitus has an association through the possible mechanisms of hypoglycaemia from therapy or from an autonomic neuropathy.
Drugs usually affect the vestibular nerve rather than the labyrinth. Drugs commonly associated with dizziness are presented in TABLE 46.3.
Table 46.3Drugs that can cause dizziness |Favorite Table|Download (.pdf) Table 46.3 Drugs that can cause dizziness
Antibiotics: streptomycin, gentamicin, kanamycin, tetracyclines
Aspirin and salicylates
Diuretics in large doses: intravenous frusemide, ethacrynic acid
Tranquillisers: phenothiazines, phenobarbitone, benzodiazepines
Cervical spine dysfunction
It is not uncommon to observe vertigo in patients with cervical spondylosis or post cervical spinal injury. It has been postulated4 that this may be caused by the generation of abnormal impulses from proprioceptors in the upper cervical spine, or by osteophytes compressing the vertebral arteries in the vertebral canal. Some instances of BPPV are associated with disorders of the cervical spine.
This may be an important aspect to consider in the patient presenting with dizziness, especially if the complaint is giddiness or lightheadedness. An underlying anxiety, particularly agoraphobia and panic disorder, may be the commonest cause of this symptom in family practice and clinical investigation of hyperventilation may confirm the diagnosis. The possibility of depression must also be kept in mind.5 Many of these patients harbour the fear that they may be suffering from a serious disorder, such as a brain tumour or multiple sclerosis, or face an impending stroke or insanity. Appropriate reassurance to the contrary is often positively therapeutic for that patient.