Treatment of Nausea and Vertigo

Nausea is the unpleasant sensation of the imminent need to vomit.¹

Nausea and vomiting represent a progressive response to increasing stimulation of a complex reflex co-ordinated by the vomiting centre in the brainstem. It receives input from the chemoreceptor trigger zone (CTZ), vestibular system, cerebral cortex and mechanoreceptors in the gut and visceral surfaces.²

Vertigo is an illusion of movement caused by disorders of the vestibular system, associated with balance disturbance and nausea.³

Blockade of the neurotransmitters and receptors involved in these pathways allows pharmacological management of nausea, vomiting and vestibular disorders.²

• This allows selection of the most appropriate and effective pharmacological therapy.²
• Drugs may mask symptoms and delay diagnosis which may be harmful in situations, e.g. drug overdose or diabetic ketoacidosis.

Pregnancy

More than 70% of women are affected by nausea or vomiting during pregnancy and causes include:⁴

• 'Morning sickness'
• Hyperemesis gravidarum
• Oesophageal reflux
• Mechanical effect of gravid uterus
• Urinary tract infection

Initial management

First trimester nausea is usually mild and self-limiting but, should vomiting continue, initial steps include:

• Reassurance and encouragement to rest
• Drinking small amounts more frequently
• Small, cold, frequent, carbohydrate-rich meals
• Use of glucose tablets and biscuits to boost blood sugar levels
• Avoidance of cold or sweet drinks, caffeine and alcohol
• Avoidance of other foods or smells that trigger nausea⁵

Further management

If symptoms persist despite the general measures above, drug therapy should be considered:

• First-line drug therapy includes the antihistamines, promethazine and cyclizine. These drugs have been widely studied and there is no apparent increased risk of congenital malformations.
• Prochlorperazine and metoclopramide are less well studied and so used as second-line therapy.
• Domperidone is not recommended as there are no published trials of safety during pregnancy.
• Other supplements such as pyridoxine (vitamin B6), multivitamins and ginger root may be effective treatments - more research is needed before these products can be recommended in practice.^5,6

Hyperemesis gravidarum

Women should be referred to secondary care for fluid and electrolyte replacement and vitamin supplementation if there is evidence of:

• Significant dehydration
• Weight loss
• Ketonuria despite drug treatment⁵

Palliative care

There are many causes of nausea in palliative patients, particularly those with advanced cancers.
Common causes include:²

• Meningeal irritation or stretch by tumour or metastases
• Abdominal or pelvic tumour causing malignant bowel obstruction or mesenteric/liver metastases
• Gastric stasis due to opioids or mechanical resistance
• Toxins (such as drugs) or metabolic disorders, e.g. hypercalcaemia or hyponatraemia

Anti-emetic treatment in palliative care is particularly challenging as:

• There are often multiple causes of nausea or vomiting which need to be treated separately
• Investigation and identification of the specific cause may not be appropriate²

Initial management

Simple interventions include:

• Correction of dehydration
• Identification and treatment of reversible causes, e.g. hypercalcaemia, constipation
• Small, carbohydrate-rich meals
• Selection of foods which patients enjoy
• Avoidance of the smell of food or cooking²

Further management

• Regular treatment with first-line anti-emetics such as cyclizine, metoclopramide or haloperidol should be prescribed for 24-48 hours and then reviewed.²
• If nausea persists, consider substitution of the first-line anti-emetic with levomepromazine ± dexamethasone as adjunct therapy.
• Ranitidine can be used to reduce gastric secretions in gastric outflow obstruction and hyoscine or octreotide may be useful in distal obstruction.²

Cytotoxic chemotherapy

Nausea remains one of the most feared and debilitating side-effects of cytotoxic therapy.⁷Symptoms vary with:

• Cytotoxic agent: cisplatin, dacarbazine and high-dose cyclophosphamide are highly emetogenic
• Women > men
• Age < 50 years
• Susceptibility to motion sickness
• Anxiety

Nausea is divided into 3 phases according to onset, which are managed differently:

Acute (first 24 hours of treatment)

• Best prevented by 5HT₃ antagonist with dexamethasone. Mirtazipine and olanzapine are cheaper and have similar 5HT binding efficacy⁸
• Addition of aprepitant improves nausea due to cisplatin
• Nabilone may be used if symptoms remain poorly controlled

Delayed (> 24 hours after treatment)

• Symptoms reduced with good control of acute phase⁷
• Prevented with dexamethasone ± metoclopramide/prochlorperazine

Anticipatory (prior to subsequent doses)

• Ideally prevented by earlier symptom control
• Lorazepam has beneficial anxiolytic and amnesic properties

Post-operative

Post-operative nausea and vomiting affects over 25% of patients⁹ and varies with:¹⁰

• Type of anaesthetic agent, particularly volatile agents and opiates
• Nature and duration of surgery
• Women > men
• Past history of post-operative nausea or motion sickness

Post-operative nausea and vomiting has traditionally been treated with metoclopramide, antihistamines or phenothiazines but only a modest reduction in symptomatology has been possible.¹ However combinations of drugs including 5HT₃ antagonists and dexamethasone are gradually improving results.¹¹

Migraine

Migraine is a paroxysmal disorder with attacks of headache, nausea, vomiting and other features.
Nausea may respond to treatment with 5HT₁ agonists but conventional anti-emetics are also useful.¹² Metoclopramide, domperidone, phenothiazine or an antihistamine should be taken with the onset of symptoms.¹³

Motion sickness

Prevention of motion sickness is achieved using hyoscine or an antihistamine. Hyoscine is most efficacious but may be poorly tolerated. Antihistamine may then be useful and the choice of compound depends largely on the desire to avoid or encourage sedation.

Other anti-emetics such as 5HT₃ antagonists, metoclopramide and domperidone are ineffective and should not be prescribed.

Other vestibular disorders

These include Ménière's disease, benign paroxysmal vertigo and vestibular neuronitis.

General measures

• Treatment of vestibular disorders depends on specific treatment of the underlying cause, combined with symptomatic control.
• Patient should be reassured that the disequilibrium should eventually be overcome by central adaptation. Anxiety exacerbates vertigo and may limit activities until these adjustments are made.
• Drugs that sedate the vestibular brainstem axis, such as prochlorperazine, reduce symptoms but prolonged use should be avoided, as they will prevent central compensation.³

Ménière's disease

• A disorder involving progressive distension of the membranous labyrinth, resulting in vertigo, tinnitus and hearing loss.
• Prochlorperazine and cinnarizine are effective treatments for acute attacks of vertigo.
• If recurrent, troublesome episodes occur, maintenance treatment is recommended.
• Betahistine is said to reduce the frequency, duration and intensity of attacks.
• Diuretic therapy and salt restriction may be useful.
• Pharmacological treatment is often inadequate so ablative procedures may be necessary.¹⁴