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Flashcards in Neurology III Deck (56)
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1

A 50-year-old man presents to his GP with a six month history of progressive deafness and tinnitus in his left ear. His wife states that recently he has been unsteady on his feet, and that his voice is becoming hoarse.

A Acoustic neuroma
B Acute suppurative otitis media
C Barotrauma
D Chronic suppurative otitis media
E Glue ear
F Ménière's disease
G Otosclerosis
H Presbyacusis
I Vestibular neuronitis

Acoustic neuroma


This patient has an acoustic neuroma. He has a hoarse voice and is unsteady on his feet because the neuroma is extending into the cerebellopontine angle compressing cranial nerve 10 and the cerebellum.

2

A 65-year-old lady presents to her GP complaining of recurrent bouts of deafness. A typical attack starts with a full feeling in the ear with tinnitus, which gradually increases in volume to be followed by nausea, vomiting, and rotational vertigo.

A Acoustic neuroma
B Acute suppurative otitis media
C Barotrauma
D Chronic suppurative otitis media
E Glue ear
F Ménière's disease
G Otosclerosis
H Presbyacusis
I Vestibular neuronitis

F Ménière's disease
This lady has Ménière's disease. The symptoms are due to a gradual increase in fluid in the endolymphatic compartment in the inner ear.

3

A 35-year-old man presents to his GP complaining of progressive bilateral hearing loss over the last year. Rinne's test is negative and on examination the tympanic membrane is normal. His father lost his hearing at a similar age and required a hearing aid.

A Acoustic neuroma
B Acute suppurative otitis media
C Barotrauma
D Chronic suppurative otitis media
E Glue ear
F Ménière's disease
G Otosclerosis
H Presbyacusis
I Vestibular neuronitis

This man has otosclerosis. He has a progressive conductive deafness due to fixation of the stapes in the oval window. It is inherited as a Mendelian dominant and is cured by an operation called stapedectomy.

4

A 21-year-old male is admitted with acute onset headache and is drowsy.

He is opening his eyes spontaneously, is disoriented but is localising to painful stimuli.


Computed tomography (CT)
Lumbar puncture (LP)
Magnetic resonance angiography (MRA)
Magnetic resonance imaging (MRI)
Positron emission tomography (PET)

CT

Urgent CT will confirm diagnosis in 95% of patients with subarachnoid haemorrhage.

Lumbar puncture is not usually required unless the history is suggestive and the CT is normal.

Blood will be present in the cerebro-spinal fluid (if a bloody tap is suspected the number of red blood cells should fall with each successive sample).

If the LP is performed six hours after onset of symptoms the supernatant fluid should be examined for xanthochromia after centrifugation.



5

Nerve injury syndromes

A Anterior interosseus nerve compression
B Carpal tunnel syndrome
C Common peroneal compression
D Erb’s palsy
E Klumpke’s paralysis
F Meralgia paraesthetica
G Posterior interosseus nerve compression
H Sciatic nerve palsy
I Tibial nerve palsy


A 40-year old man has been lying unconsciously on his left side for 14-hours. When he recovers he notices that he cannot dorsiflex his left foot. On examination there is reduced sensation over the dorsum of the foot.

Common peroneal compression


This patient has a common peroneal nerve palsy due to nerve compression against the head of the fibula when lying unconscious. Spontaneous recovery may be expected but surgical decompression may be required.

6

Nerve injury syndromes

A 55-year old lady presents to her GP with a 3-month history of pain along the left forearm’s radial border. On examination there is weakness of pinch and weakness of the long thumb flexor and flexor profundis to the index and middle fingers.

A Anterior interosseus nerve compression
B Carpal tunnel syndrome
C Common peroneal compression
D Erb’s palsy
E Klumpke’s paralysis
F Meralgia paraesthetica
G Posterior interosseus nerve compression
H Sciatic nerve palsy
I Tibial nerve palsy


Anterior interosseus nerve compression

This lady has anterior interosseus nerve compression, which is a median nerve branch that is being compressed under the fibrous origin of flexor digitorum sublimis. Treatment is surgical decompression.

7

Nerve injury syndromes

A 35-year old pregnant lady presents to her GP complaining of pain and paraesthesiae over the upper outer thigh. On examination there is reduced sensation in this area.

A Anterior interosseus nerve compression
B Carpal tunnel syndrome
C Common peroneal compression
D Erb’s palsy
E Klumpke’s paralysis
F Meralgia paraesthetica
G Posterior interosseus nerve compression
H Sciatic nerve palsy
I Tibial nerve palsy

Meralgia paraesthetica


This lady has meralgia paraesthetica due to compression of the lateral cutaneous nerve of the thigh on leaving the pelvis just medial to the ASIS. It is common in pregnancy and treatment includes cortisone and local anaesthetic injections.

8

Nerve injury syndromes

A Anterior interosseus nerve compression
B Carpal tunnel syndrome
C Common peroneal compression
D Erb’s palsy
E Klumpke’s paralysis
F Meralgia paraesthetica
G Posterior interosseus nerve compression
H Sciatic nerve palsy
I Tibial nerve palsy


A 70-year old lady who fractured her right forearm six-months ago presents to her GP complaining of weakness of her right thumb and fingers. On examination there is weakness of the long finger extensors and short and long extensors of the thumb, but no sensory loss.

Posterior interosseus nerve compression


This lady has compression of the posterior interosseus nerve, which is a branch of the radial nerve that is compressed on passing through the supinator muscle. Treatment involves surgical decompression and springed splints to extend fingers.

9

A 50-year old type 2 diabetic man presents to his GP complaining of pain, tingling and numbness in the thumb, index and middle fingers, which keeps him awake at night. He has to shake his wrist to bring about relief.

Nerve injury syndromes

A Anterior interosseus nerve compression
B Carpal tunnel syndrome
C Common peroneal compression
D Erb’s palsy
E Klumpke’s paralysis
F Meralgia paraesthetica
G Posterior interosseus nerve compression
H Sciatic nerve palsy
I Tibial nerve palsy

This man has carpal tunnel syndrome due to compression of the median nerve as it passes under the flexor retinaculum. Treatments include the use of diuretics, steroid injections, splints and decompression.

10

Upper limb nerve injuries

A Anterior interrosseous nerve lesion
B Injury to the lower cord of brachial plexus
C Injury to the radial nerve at the level of the axilla
D Injury to the radial nerve at the level of the mid-shaft of humerus
E Injury to the radial nerve at the level of the wrist
F Injury to the upper cord of brachial plexus
G Median nerve compression
H Posterior interosseous nerve lesion
I Ulnar nerve injury

A 65-year-old woman presents to the Emergency department with inability to extend the metacarpophalangeal joints of her right hand and wrist drop. These happened after she injured her right arm when she tripped and fell over on the pavement. She also has altered sensation over the region of the anatomical snuff box. The triceps reflex is present.


The ulnar nerve, which arises from the C8 and T1 nerve roots is an important motor nerve of the hand.

Laceration at the level of the wrist, usually from trauma, is the commonest cause of low ulnar nerve lesions. It can also be affected by pressure from a deep ganglion. Lesion of the ulnar nerve at the level of the wrist produces hypothenar wasting and clawing of the hand due to the action of unopposed long flexors.

The sensory loss is over the little and ring fingers. Finger abduction is affected and the loss of thumb adduction makes pinch difficult. This is caused due to paralysis of the adductor pollicis and the first palmar interossei which results in flexion of the thumb due to the unopposed action of the flexor pollicis longus muscle. This can be demonstrated when the patient is asked to grasp a card between his thumb and index finger (Froment's sign).



11

Upper limb nerve injuries

A Anterior interrosseous nerve lesion
B Injury to the lower cord of brachial plexus
C Injury to the radial nerve at the level of the axilla
D Injury to the radial nerve at the level of the mid-shaft of humerus
E Injury to the radial nerve at the level of the wrist
F Injury to the upper cord of brachial plexus
G Median nerve compression
H Posterior interosseous nerve lesion
I Ulnar nerve injury

A 25-year-old man is brought to the Emergency department with a painful shoulder and inability to use his left hand after being involved in a high speed motorcycle accident.

On examination, there is weakness of the wrist with inability to extend the wrist or fingers of his left hand. Extension of the elbow is also affected and triceps reflex is absent. Sensation is lost over the dorsum of the forearm.


Injury to the radial nerve at the level of the axilla

The radial nerve arises from C5 - T1 and is an important nerve in the dorsal aspect of the arm and forearm. It supplies:

The triceps
Brachioradialis
Wrist extensors
Extensor digitorum longus muscles.
The sensory supply is over the dorsum of the thumb and the first web space, and the dorsum of the forearm.

The clinical pattern of disability depends on the level of injury. In very high lesions, where the radial nerve may be compressed in the axilla, for example, high-speed RTA or inappropriate use of crutches, there is:

Complete paralysis of the triceps
Paralysis of the extensors supplied by the radial nerve (thus wrist drop)
Absent triceps reflex.
In such lesions, there is sensory loss over the dorsum of the forearm in addition to sensory loss over the dorsum of the thumb and the first web space.

In high lesions, such as in fractures of the humerus (particularly mid-shaft fractures where the radial nerve lies in the spiral groove), or due to prolonged tourniquet pressure, there is:

Weakness of the radial extensors of the wrist
Numbness over the anatomical snuff box.
They are also seen in patients who fall asleep with the arm dangling over the back of a chair ('Saturday night palsy').

12

Upper limb nerve injuries

A Anterior interrosseous nerve lesion
B Injury to the lower cord of brachial plexus
C Injury to the radial nerve at the level of the axilla
D Injury to the radial nerve at the level of the mid-shaft of humerus
E Injury to the radial nerve at the level of the wrist
F Injury to the upper cord of brachial plexus
G Median nerve compression
H Posterior interosseous nerve lesion
I Ulnar nerve injury

A 28-year-old male presents to the Emergency department with a deep laceration to the left wrist when he was slashed with a broken glass whilst involved in a brawl in his local pub.

On examination, he is unable to spread his fingers or pinch a pen from the table. There is loss of sensation over his little and ring fingers.

Ulnar nerve injury

13

Cerebral blood flow:

Accounts for 30% of the total cardiac output

Autoregulation fails below a mean arterial pressure (MAP) of 65 mm Hg

Is controlled mainly through the autonomic system

Is increased by hypocapnia

Is increased by hypoxia

Is increased by hypoxia

The carotid arteries supply two thirds of cerebral blood flow (CBF), and the vertebral arteries one third. CBF is 15% of cardiac output. Cerebral blood volume is 10% of the intracranial space, mainly in the cerebral veins.

Autoregulation maintains a constant CBF between a mean arterial pressure (MAP) of 50 and 150 mm Hg. Above and below these levels CBF has a linear relationship with MAP. These levels may be increased in patients with hypertension so there is a greater risk of cerebral ischaemia with a 'normal' blood pressure. In brain injury it is cerebral perfusion pressure (CPP) that determines CBF.

CPP is: MAP - (intracranial pressure [ICP] + venous pressure [VP])

Venous pressure is usually zero. With raised ICP, compensatory arterial dilatation maintains CBF until the lower autoregulatory level of 50 mm Hg is reached. It then falls.

Hypercapnia increases CBF: there is a linear relationship between 2.7 kPa and 10.7 kPa.

Hypoxia does not increase CBF significantly until below 6.7 kPa. Giving 100% oxygen decreases CBF by 10%.

Hypothermia decreases CBF: a 10°C reduction in temperature reduces CBF by 20-50%.

Hyperthermia increases CBF.

14

Which of the following is associated with a sciatic nerve injury following a severe fracture dislocation of the hip?

An inability to stand on the heel of the affected foot

Loss of knee jerk

Loss of sensation along the medial border of the foot

Normal power of knee flexion

Unaffected ankle jerk

The patient would be unable to stand on heel or toes with a sciatic nerve lesion. Sometimes limited walking is possible.1

The medial border of the foot is supplied by the saphenous nerve, a branch of the femoral nerve. A sciatic nerve lesion causes anaesthesia of the whole foot (except medial border) and posterolateral calf in the lower two thirds (the medial calf s supplied by the posterior femoral cutaneous nerve).

The knee jerk is mediated by femoral nerve.

There is paralysis of the hamstrings and all muscles of the lower leg and foot. If the nerve damage is in the upper thigh rather than at gluteal level, some knee flexion (hamstrings) may be preserved.

The ankle jerk is S1. The Sciatic nerve is L4,5, S1,2,3.

15

A diagnosis of prolapsed intervertebral disc would be supported by which of the following?

Bilateral symmetrical nerve involvement
Compressions of a single nerve root
No evidence of nerve compression
Pain which is unremitting in character
Pain which is worse on resting

Compressions of a single nerve root

A diagnosis of prolapsed intervertebral disc would be supported by compressions of a single nerve root. If more than one root is involved the diagnosis is less likely.

Pain which is unremitting in character indicates another cause.

Pain which is worse on resting indicates another cause such as infection, tumour or metabolic disease.



16

Which of the following associations of muscles and nerve supply is correct?


Deltoid and C4
Gastrocnemius and S3
Long flexors of fingers and C8
Quadriceps and L1
Triceps and C6

Long flexors of fingers and C8

The deltoid is supplied by the axillary nerve which has a nerve root of C5, C6.

The gastrocnemius is supplied by the tibial nerve which has a nerve root of S1, S2.

Rectus femoris and the three vastus muscles (intermedius, medialis and lateralis) are all supplied by the femoral nerve which has a nerve root of L2, L3, L4.

Triceps brachii is supplied by the radial nerve which has a nerve root of C7.



17

A lesion of the facial nerve in the internal auditory meatus will affect which of the following?

Accommodation
Lacrimation
Sensation over the cheek
Sweating over the cheek
Taste, on the posterior third of tongue

Lacrimation

The extent of dysfunction depends on the level of injury. If it is proximal to geniculate ganglion, for example,internal auditory meatus, taste is lost in the anterior two thirds of the tongue. Also secretion from submandibular, sublingual and lacrimal glands is impaired.

Hyperacusis is due to paralysis of stapedius. The orbicularis oculi is affected, causing inability to blink/close eyelids.

Sensation over the face is supplied by the trigeminal nerve, and sweat glands are controlled by the sympathetic nervous system, for example, anhydrosis in Horner's syndrome.



18

Which of the following is an unusual feature of chronic subdural haematoma in an adult ?

Bilateral papilloedema
Fluctuating level of consciousness
Hemiparesis
Internuclear ophthalmoplegia
Unequal pupils

Internuclear ophthalmoplegia

Chronic subdural haematoma is classically associated with fluctuating conscious level and cognitive function.

Bilateral papilloedema may occur with raised intracranial pressure.

Bilateral internuclear ophthalmoplegia is associated with multiple sclerosis, and unilateral lesions of medial longitudinal fasciculus may occur with small brain stem infarcts.

Unequal pupils are associated with rapid transtentorial coning in extradural haemorrhage, leading to ipsilateral dilated pupil, followed by bilateral fixed dilated pupils.

"[In subdural haematoma] characteristic herniation syndromes may develop as the brain shifts. As the medial temporal lobe, or uncus, herniates past the tentorium, it can compress the ipsilateral posterior cerebral artery, oculomotor nerve, and cerebral peduncle. Clinically, the consequent oculomotor nerve palsy and cerebral peduncle compression often are manifested by an ipsilaterally dilated pupil and a contralateral hemiparesis." eMedicine

19

Which of the following is consistent with brainstem death?

Absence of pupillary light reflexes
Absent tendon reflexes
Cheyne-Stokes breathing
Periodic breathing
Presence of cold caloric reflex

Absence of pupillary light relfexes

Brain stem death is characterised by

Apnoea
Fixed and dilated pupils
No response to cold caloric testing.
Spinal reflexes may be preserved.



20

Which of the following statements regarding upper limb nerve injuries is correct?

Injury to the median nerve results in a claw hand

Injury to the median nerve results in a wrist drop

Injury to the radial nerve results in loss of sensation in the anatomical snuffbox

Injury to the ulnar nerve results in loss of sensation over the palmar aspect of the index finger

Injury to the ulnar nerve results in loss of sensation over the thumb

Injury to the radial nerve results in loss of sensation in the anatomical snuffbox

Radial nerve injury results in a wrist drop and a variable amount of sensory loss. The anatomical snuffbox is usually involved.

Median nerve injury may result in loss of sensation over the thumb, index, middle and the lateral half of the ring finger. However, the only autonomous areas of sensory loss are the pulp pads of the index and middle fingers. The hand is held with the index finger held straight and the other fingers flexed.

Ulnar nerve injury results in a claw hand deformity and loss of sensation over the medial half of the ring finger and little finger.



21

Regarding Erb's palsy, which of the following statements is correct?

Affects the small muscles of the hand

Is more common after 'head-first' delivery

Is the commonest form of birth trauma

May be due to injury of the lower brachial plexus

May lead to wasting of the arm

May lead to wasting of the arm

Minor soft tissue injuries to the head, for example following scalp electrode placement or caput succedaneum, occur more commonly.

Erb's palsy involves injury to the upper brachial plexus (C5-6), and leads to wasting of arm, but not the intrinsic muscles of the hand, which would be the result of lower brachial plexus injury.

Erb's palsy is more common in large-for-dates infants and breech deliveries.

Klumpke described the clinical picture of lower brachial plexus injury (C7-T1).



22

Which of the following is not of importance in establishing the diagnosis in dysphagia?

Constipation
Horner's syndrome
Intermittent diplopia
Koilonychia
Raynaud's phenomenon

Constipation

Constipation is not of importance in establishing the diagnosis of dysphagia.

Horner's syndrome may be caused by damage to the sympathetic supply to the eye by advanced malignant disease in the chest. The most common cause will be a lung tumour (Pancoast's tumour [Henry Pancoast, American radiologist 1932]) which may also cause compression of the oesophagus.

Intermittent diplopia may suggest myasthenia gravis.

Koilonychia (spoon-shaped nails) may suggest chronic iron deficiency anaemia which can be associated with dysphagia due to a post-cricoid web (Patterson Brown-Kelly syndrome [both ENT surgeons: described in 1919 before Plummer & Vinson in 1921]). This is a premalignant condition.

Raynaud's phenomenon may suggest the CREST syndrome or systemic sclerosis.

23

Parkinsonism may result from which of the following?

Amitriptyline therapy
Cabergoline therapy
Carbon dioxide retention
Mercury poisoning
Wilson's disease

Wilson's disease

Parkinsonism is a typical side effect of most anti-psychotic agents but effects are reduced with the newer anti-psychotics such as olanzapine (not with the tricyclic antidepressant [TCA] amitriptyline).

However, extrapyramidal effects are seen with Wilson's disease, carbon monoxide poisoning, and with methoxy trifluoromethyl phenyl acetic acid (MTPA) abuse.

Cabergoline, a dopamine agonist, is a treatment for Parkinson's disease.

24

Regarding the ulnar nerve, which of the following statements is true?

Has a number of branches above the elbow
Innervates the abductor pollicis brevis
Innervates the first dorsal interosseus muscle
Innervates the lateral half of the flexor digitorum profundus
Originates from the lateral cord of the brachial plexus

Innervates the first dorsal interosseus muscle

The ulnar nerve is formed from the medial cord nerve roots of C7-T1.

Originating in the brachial plexus, it descends down the arm before passing around the medial epicondyle of the elbow (the so-called funny bone) and then passes between the heads of flexor carpi ulnaris (FCU).

It gives some cutaneous branches just before the wrist whilst the motor branches pass around the hook of hamate.

Its motor contribution is to all small muscles of the hand except the lateral two lumbricals as well as FCU and flexor digitorum profundus (FDP).

Its sensory supply is to the one and a half ulna side fingers.



25

Which of the following regarding nerve innervation is correct?

Abductor pollicis brevis is supplied by the median nerve

Lower cord of the brachial plexus comprises C8, T1 and T2

Opponens pollicis muscle is innervated by the ulnar nerve

The diaphragm is innervated by C5, C6 and C7

The knee jerk is innervated by L4 and L5 segments

Abductor pollicis brevis is supplied by the median nerve

Opponens pollicis is supplied by the median nerve, as are most of the thenar eminence.

The diaphragm is innervated by C345: 'keeps the diaphragm alive'.

Lower cord is C8 and T1.

The knee jerk (patella reflex) is a deep tendon reflex innervated by L2, L3 and L4 with primary innervation coming from L4.



26

Regarding extradural haematoma which of the following is correct?

Limited by suture lines
Not usually associated with a skull fracture
Typically biconcave on a CT scan
Usually associated with lucid interval
Usually due to damage to the posterior branch of the middle meningeal artery

Limited by suture lines

Extradural haematoma is usually due to damage to the anterior branch of the middle meningeal artery.

Since the dura has strong attachments to the cranium along the suture lines, contrary to subdural haematomas, extradural haematomas are limited by the suture lines. Due to this feature they have a characteristic biconvex appearance on a CT scan.

Though the majority are associated with a skull fracture this is not always the case; it could result from a direct local impact (coup) without a fracture. Frequently the initial injury is not severe, often a blow to the temporal regions (for example, with a cricket ball) where the relatively thin skull overlies the meningeal artery could lead to an extradural haematoma.

The well described 'lucid interval' of an extradural haematoma is in fact the exception - the majority of patients progressively deteriorate from the time of injury.



27

Which of the following is true of the neurological system?

A complete CN III palsy will cause the affected eye to be turned outwards and upwards

A lesion of the cerebellopontine angle will produce a CN VII lesion with sparing of the frontalis muscle

A positive Rinne's test indicates the presence of conductive deafness

Quadrantic hemianopia is associated with lesions of the parietal lobe

Sensation to the anterior 2/3rds of the tongue will be lost in a lesion of the glossopharyngeal nerve

Quadrantic hemianopia is associated with lesions of the parietal lobe

The affected eye will deviate down and out with a dilated pupil often unreactive to light and accommodation. Complete or partial ptosis may also be present.

Often caused by an acoustic neuroma. The frontalis is spared in all upper motor neurone lesions involving cranial nerve VII, not in this case.

A positive Rinne's test is when air conduction is better than bone conduction, a normal result. A negative Rinne's test indicates the presence of conductive deafness.

Parietal lesions cause lower quadratic hemianopia whilst temporal lesions cause upper quadrantic hemianopia.

The facial nerve supplies the anterior 2/3rds of the tongue.

28

Which of the following is true in spinal cord injury?

Hemisection of the spinal cord results in contralateral paralysis

Hemisection of the spinal cord results in loss of contralateral proprioception

Hemisection of the spinal cord results in loss of ipsilateral pain sensation

Section of the anterior cord results in impaired proprioception, touch and vibration sense

Section of the anterior cord results in paralysis below the level of the lesion

Section of the anterior cord results in paralysis below the level of the lesion

Injury to the anterior spinal cord results in paralysis (motor loss) below the level of the lesion, with proprioception, touch and vibration senses being preserved.

Hemisection of the cord (Brown-Séquard syndrome) results in ipsilateral paralysis and loss of proprioception, touch and vibration sense, together with loss of pain and temperature sensation on the contralateral side.





29

A 30-year-old female is scheduled to have an elective thymectomy. She is known to have myasthenia gravis and takes pyridostigmine.

5% of patients with myasthenia gravis have hyperplasia of the thymus

It is caused by antibodies against pre-synaptic acetylcholine receptors

Myasthenic crisis may be provoked by infection

Pyridostigmine should not be omitted on the morning of surgery

Tracheostomy is frequently performed to improve weaning from post-operative ventilatory support

Myasthenic crisis may be provoked by infection

Myasthenia gravis is an autoimmune disease characterised by skeletal muscle weakness and increased fatigability.

Ninety per cent of patients have antibodies against the post-synaptic acetylcholine receptors at the neuromuscular junction. Sixty five per cent of patients with myasthenia gravis have hyperplasia of the thymus and 12% have a thymoma.

Treatment is with acetylcholinesterase inhibitors, for example, pyridostigmine, which may cause a cholinergic crisis in over-dosage. Side effects of treatment include

Diarrhoea
Urinary frequency
Meiosis
Excessive salivation
Lacrimation.
A myasthenic crisis (sudden worsening and spreading weakness) may be provoked by drug omission, infection and stress.

Pre-operative assessment of respiratory function is important. Pyridostigmine is usually withheld on the morning of surgery and then restarted in reduced dosage post-operatively.

A tracheostomy does improve weaning from ventilatory support, but it is not performed routinely after a thymectomy. These patients are often extubatable within 24 hours on the ICU if not immediately after the surgery

30

A 20-year-old male presents for lower limb contracture release. He is known to have muscular dystrophy.

A pre-operative 12 lead ECG is required

Hypokalaemia and myoglobinuria may occur post-operatively

Plasma creatinine kinase concentrations will be low

Post-operative chest infections are uncommon

These patients quickly develop tolerance to opioid analgesics

A pre-operative 12 lead ECG is required

Muscular dystrophies are rare hereditary disorders of muscle. Progressive destruction of skeletal and cardiac muscle occurs by a mechanism thought to involve abnormal muscle membrane function.

Plasma creatine kinase level may be increased. Patients tend to present with limb contractures. They have weak respiratory muscles which impairs ventilation and sputum clearance.

Pre-existing and postoperative chest infections are common and they are especially sensitive to opioids and other respiratory depressant drugs. Severe hyperkalaemia and myoglobinuria may occur following prolonged exposure to volatile anaesthetic agents, therefore regional techniques are preferred.

As arrhythmias and cardiac failure may occur due to myocardial involvement, an ECG and echocardiogram will provide valuable preoperative information on cardiac function.