Neuropathies Flashcards by Adele Atkins

What is a mononeuropathy

Lesions of individual peripheral or cranial nerves

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From which nerve roots is the median nerve formed of?

C6-T1

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What is the function of the median nerve

Precision grip

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Which muscles are innervated by the median nerve

Lumbricals
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis

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What syndrome results from compression of the median nerve at the wrist?

Carpal tunnel syndrome

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Describe the symptoms of carpal tunnel syndrome

Aching pain in the hand and arm especially at night and paraesthesia in the thumb, index and middle fingers
Relieved by dangling hand over the edge of the bed and shaking it
May be sensory loss and weakness of abductor pollicis brevis and wasting of the thenar eminence
Light touch and 2 point discrimination and sweating may be impaired

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What causes carpal tunnel

Swelling or compression of the tunnel - myxoedema, prolonged flexion (colles splint), acromegaly, myeloma, local tumours, rheumatoid arthritis, amyloidosis, pregnancy, sarcoidosis

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What tests are requested in carpal tunnel

Neurophysiology - confirms the site of the lesion and severity
Phalens test - Maximal wrist flexion for 1 minute
Tinnels test - tapping over the nerve on the wrist can induce tingling

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How is carpal tunnel syndrome treated?

Splinting
Steroid injections
Decompression surgery

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What is tarsal tunnel syndrome

Unilateral sole pain, following tibial nerve compression

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Which nerve roots form the ulnar nerve

C7-T1

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What is the ulnar nerve vulnerable to?

Elbow trauma

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What are the signs of ulnar nerve damage

Weakness/wasting of medial wrist flexors, interossei and medial 2 lumbricals (claw hand - more marked wrist lesions with digitorium profundus intact). Hypothenar eminence wasting, weak 5gth digit abduction and 4th, 5th DIP joint flexion, sensory loss over medial 1 and half fingers and ulnar side of the hand

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Where does compression of the ulnar nerve most commonly happen?

The epicondylar groove or at the point where the nerve passes between the two heads of flexor carpi ulnaris.
May also less commonly occur at the Guyon’s canal (between pisiform and hamate bones)

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How are ulnar nerve mononeuropathies treated?

Rest and avoid pressure on the nerve
Elbow splinting at night time to prevent flexion >60
Splint for the hand may prevent permanent clawing
For chronic neuropathy or if splinting fails, a variety of surgical procedures have been tried. Decompression in situ or medial epicondylectomies are effective in 50% but many will recur

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What is the function of the radial nerve?

Opens the fist

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Which nerve roots form the radial nerve?

C5-T1

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How may the radial nerve become compressed?

Compression against the Humerus

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How do you test for radial nerve compression?

Wrist and finger drop with elbow flexed and arm pronated

Sensory loss is variable - the dorsal aspect of the root of the thumb - anatomical snuffbox is more reliably affected

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Which muscles are involved in radial nerve compression?

Brachioradialis 
Extensors
Abductor pollicis longus 
Supinator
Triceps

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What is the function of the phrenic nerve

Supplies the diaphragm

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Which nerve roots form the phrenic nerve

C3,4,5

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What do lesions of the phrenic nerve cause?

Orthopnoea with a raised hemidiaphragm on CXR

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What causes lesions of the phrenic nerve?

Lung cancer
TB
Paraneoplastic syndrome
Myeloma
Thyoma 
Cervical spondylosis/trauma
Thoracic surgery 
Infections - HZV, HIV, Lyme disease
Muscular dystrophy

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Describe brachial plexus compression symptoms

Pain/paraesthesia and weakness in the affected arm in a variable distribution

What causes brachial plexus compression?

``` Trauma Radiotherapy Prolonged wearing of a heavy rucksack Cervical rib Thoracic outlet compression Neuralgic amyotrophy ```

Which nerve roots form the lateral cutaneous nerve of the thigh?

L2-3

What does compression of the lateral cutaneous nerve of the thigh cause?

Meralgia paraesthetica

Describe the symptoms of meralgia paraesthetica

Anterolateral burning thigh pain

Where is the compression of the lateral cutaneous nerve of the thigh

Entrapment

Which nerve roots form the sciatic nerve

L4-S3

What causes sciatic nerve mononeuropathy

Pelvic tumours | Fractures to the pelvis or femur

What symptoms do lesions of the sciatic nerve cause

Lesions affect the hamstrings and all the muscles below the knee (foot drop) with loss of sensation below the knee laterally

Which nerve roots form the common peroneal nerve

L4-S1

Where does the common peroneal nerve originate

From the sciatic nerve just above the knee

Where is the common peroneal nerve often damaged

Often damaged as it winds round the fibular head

What are the signs of common peroneal nerve damage

Foot drop Weak ankle dorsiflexion/eversion Sensory loss over dorsal foot

Where does the tibial nerve originate?

From sciatic nerve just above knee

Which nerve roots form the tibial nerve?

L4-S3

What do lesions of the tibial nerve cause?

Inability to stand on tiptoes (plantarflexion of the foot), invert the foot or flex the toes with sensory loss over the sole

What is mononeuritis multiplex

Involvement of 2 or more peripheral nerves

What causes mononeuritis multiplex

``` DM Connective tissue disease Vasculitis Sarcoidosis Amyloidosis Leprosy ```

Which investigation is used to define the anatomic site of lesions in mononeuritis multiplex?

EMG

What are polyneuropathies

Motor and/or sensory disorder of multiple peripheral or cranial nerves Usually symmetrical, widespread and often worse distally

How are polyneuropathies classified?

Chronicity Function Pathology

How are polyneuropathies diagnosed?

History - time course, nature of symptoms, preceding/associated events, travel, alcohol and drug use, STIs and FH

Which conditions result in palpable nerve thickening

Leprosy | Charcot marie tooth

What investigations are done in polyneuropathies

``` FBC ESR U&Es LFT TSH B12 Electrophoresis ANA ANCA CXR urinalysis LP and specific genetic tests for inherited neuropathies Lead level Antiganglioside antibodies Nerve conduction studies distinguish demyelinating from axonal causes ```

Describe sensory neuropathy

Numbness, pins and needles, paraesthesia, affects glove and stocking distribution, difficulty handling small objects. Signs of trauma, joint deformation Diabetic and alcoholic neuropathies are typically painful

Which disorders is sensory neuropathy common in

DM CKD Leprosy

Which disorders is motor neuropathy common in

Guillian barre syndrome Lead poisoning Charcot Marie Tooth disease

Describe the symptoms of a motor neuropathy

Progressive, weak or clumsy hands, difficulty in walking (falls and stumbling), difficulty breathing (decreased vital capacity)

What are the signs of a motor neuropathy

LMN lesion Wasting and weakness more marked in the distal muscles of hands and feet (foot or wrist drop) Reflexes are reduced or absent

Describe the symptoms of cranial nerve polyneuropathy

Swallowing/speaking difficulty | Diplopia

How are polyneuropathies treated?

Involve physio and OT Foot care and shoe choice are important in sensory neuropathies to minimize trauma Splinting joints helps prevent contractures in prolonged paralysis In Guillian barre - IVIG helps Vasculitis causes - steroids and immunosuppressants Neuropathic - amitriptyline, duloxetine, gabapentin or pregabalin

What is autonomic neuropathy

Sympathetic and parasympathetic neuropathies may be isolated or part of a generalised sensorimotor peripheral neuropathy

What causes autonomic neuropathy

``` DM Amyloidosis Guillian Barre Sjogrens HIV Leprosy SLE Toxic Genetic Paraneoplastic ```

List some signs of sympathetic autonomic neuropathy

Postural hypotension Decreased sweating Ejaculatory failure Horner syndrome

List the signs of parasympathetic autonomic neuropathy

``` Constipation Nocturnal diarrhoea Urine retention Erectile dysfunction Holmes Adie pupil ```

List some autonomic function tests

BP - Postural drop of >20/10mmHg is abnormal ECG - A variation of <10bpm with respiration is abnormal Cystometry - Bladder pressure studies Pupils - Instil 0.1% adrenaline dilates if post-ganglionic sympathetic denervation, 2.5% cocaine dilates if normal, 2.5% methacholine constricts if parasympathetic Paraneoplastic antibodies - AntiHU, antiYO, antiRI, antiamphysin, anti CV2, antiMA2

What does primary autonomic failure occur with?

Alone or as part of multisystem atrophy or with parkinsons disease