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Neuro & Special Senses > Neuropathies and Spinal Cord Lesions > Flashcards

Neuropathies and Spinal Cord Lesions Flashcards

1
Q

What are the cervical myotomes?

A 
C5 - shoulder abduction and adduction, elbow flexion
C6 - elbow flexion and wrist extension
C7 - elbow extension, wrist flexion
C8 - wrist flexion, finger flexion
T1 - finger abduction
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2
Q

What myotomes are the biceps and brachioradialis reflexes?

A

C5 and C6

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3
Q

What myotome is the triceps reflex?

A

C7

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4
Q

What are the lumbosacral myotomes?

A

L2 - hip flexion and adduction
L3 - hyp adduction and knee extension
L4 - knee extension, foot inversion and dorsiflexion
L5 - hip extension and abduction, knee flexion, great toe dorsiflexion
S1 - knee flexion, foot plantarflexion and eversion

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5
Q

What are the myotomes for the lower limb reflexes?

A

Knee - L3/4

Great toe - L5

Ankle - S1

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6
Q

What is the common cause of spinal cord disease in 16-30 yo.?

A

Likely trauma of C4/5 or C5/6

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7
Q

What is the common cause of spinal cord disease in 30-50 yo.?

A

Likely disc disease of C5/6 or L4/5 or L5/S1

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8
Q

What is the common cause of spinal cord disease in 40+ yo.?

A

Likely malignancy

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9
Q

What are the potential causes of spinal cord problems?

A 
Trauma
Iatrogenic
Osteoporosis
Corticosteroid use
Osteomalacia
Osteomyelitis
Tumour infiltration
Disc herniation
Infection
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10
Q

How do spinal cord problems present?

A 
Back pain
Numbness and paraesthesia
Weakness and paralysis
Bladder and bowel dysfunction
Hyper-reflexia
Spinal shock
Neurogenic shock
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11
Q

What happens in spinal shock?

A

Loss of reflexes, tone and motor function

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12
Q

What happens in neurogenic shock?

A

Following cervical or high thoracic injury

Bradycardia, hypotension, warm dry extremities, peripheral vasodilation, venous pooling, priapism, low cardiac output

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13
Q

When should a CT C Spine <1hr be considered?

A 
GCS < 13
Intubated
>65yo
High impact injury
Focal neurological deficit
Paraesthesia of UL or LL
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14
Q

How is Spinal cord compression managed?

A

Immobilise C spine - collar and backboard
Intubate if above C5
Decompressive surgery
Supportive management - VTE prophylaxis, maintain vitals, nutrition, catheter, laxatives, pressure sore prevention

If malignancy - palliative

Abscess - IV Vancomycin, metronidazole and cefotaxime + surgery

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15
Q

What are the ascending tracts?

A

Take sensory information from the body to the brain

Dorsal columns - posterior spinal cord - fine touch, vibration, proprioception
Decussate at the medulla

Spinothalamic tracts - anterior part of spinal cord - pain and temperature
Decussate immediately, ascend contralaterally

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16
Q

What are the descending tracts?

A

Motor information from UMNs to muscles

Pyramidal - conscious control, extrapyramidal - unconscious, reflexive

Pyramidal - corticospinal tract and corticobulbar tract

Extrapyramidal - reticulospinal, vestibulospinal, rubrospinal and tectospinal
All originate in the brainstem, carry motor fibres for unconscious responsive movements.

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17
Q

What is the corticospinal tract?

A

Communicates with primary motor cortex, premotor cortex, supplementary motor cortex

Converges in internal capsule, then divides into lateral and anterior tracts
Lateral decussates in medulla, anterior ipsilateral

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18
Q

What is the corticobulbar tracts?

A

From primary motor cortex and terminate in the brainstem at the motor nuclei

Then synapse onto cranial nerve motor nuclei - LMNs to supply the head and neck

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19
Q

What are the signs of UMN lesions?

A 
Hypertonia
Spastic
Fasciculations absent
Minimal atrophy
Exaggerated reflexes/clonus
Babinski's sign present
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20
Q

What are the signs of LMN lesions?

A 
Hypotonia
Flaccid
Fasciculations present
Marked atrophy
Diminished reflexes
Absent Babinski's
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21
Q

What is the pathophysiology behind the difference in UMN and LMN damage?

A

Impaired ability for motor neurones to regulate descending signals, so gives disordered spinal reflexes.

Corticospinal tract can help in conscious inhibition - if sever UMNs, there is loss of inhibitory tone of muscles
No LMN inhibition leads to LMN activation and constant contraction of muscles, sensory info not received so body thinks we are not compensating. No UMN to inhibit LMN anymore - lots of firing.
Initial flaccid paralysis then hypertonia, hypereflexia.

If LMNs damaged or lost, nothing to tell muscles to contract, so hypotonia and flaccid paralysis.

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22
Q

How do UMN and LMN lesions differ in the face?

A

Upper half of the face receives bilateral cortical supply, so UMN damage forehead is spared

Lower half receives contralateral cortical supply

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23
Q

What is decerebrate and decorticate posturing?

A

Decerebrate posturing - upper limb extension, a lesion below the red nucleus prevents the red nucleus from activating upper limb flexors

Decorticate posturing - upper limb flexion - a lesion above the red nucleus prevents inhibition of the red nucleus so there is flexion of the upper limb

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24
Q

What is the red nucleus?

A

In the rostral midbrain involved in motor coordination

Pale pink due to iron - Hb and ferritin

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25
Q

What are the types of ascending tracts?

A

Dorsal column-medial lemniscus - vibration, proprioception, fine touch
= fasciculus gracilis (below T6-T8) and fasciculus cuneatus (above T6-T8 but not the head)

Spinothalamic tract (anterolateral system)
anterior - crude touch and pressure, lateral - pain and temp

Spinocerebellar tracts - transmits proprioceptive signals from body to brain

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26
Q

Where do the nerve fibres cross in the spinothalamic tract?

A

At the anterior grey commissure at the level of the spinal nerve

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27
Q

How can you clinically assess the ascending tracts?

A

Dorsal columns - vibration with 128Hz tuning fork, joint proprioception with small-joint movement, light touch - cotton wool

Spinothalamic tracts - pain with pin-prick, temp - cool and warm metal object

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28
Q

What are some of the signs that the lesion is within the spinal cord?

A

Mixed upper and lower neurone signs - as affects CNS (UMNs) and spinal nerves leaving SC (LMNs)

Sensory level - well demarcated, e.g. at T10 = umbilicus

Sphincter involvement - disruption of urinary or bowel function

Autonomic dysfunction/dysreflexia - indicates lesion is above T6

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29
Q

What are the signs of autonomic dysreflexia?

A 
Hypertension
Bradycardia
Urinary retention
Constipation
Sweating
Flushing above level of the lesion
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30
Q

What signs can help suggest where in the spinal cord is the problem?

A

If all four limbs - likely cervical
If only lower limbs - thoracic
Respiratory difficulties and diaphragm affected - avoe C3

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31
Q

What occurs in complete transection?

A

Interruption of all ascending and descending tracts bilaterally

Results in bilateral loss of motor function, complete loss of all modes of sensation below level of the lesion

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32
Q

What is seen in Brown-Sequard syndrome?

A

Damage to one lateral half of the spinal cord

Most commonly occurs in the cervical region

Spastic paralysis and loss of pain, temp, sensation in one leg (corticospinal and spinothalamic tracts)

Loss of fine touch, proprioception and vibration sense in the other

Dorsal columns ascend ipsilaterally, so lesion will be on same side of body as dorsal column symptoms

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33
Q

What is seen in anterior cord syndrome?

A

Front of spinal cord is damaged, but posterior part is spared

There is only one anterior spinal artery - blockage can damage whole anterior part - stroke within spinal cord

Causes bilateral disruption to spinothalamic tracts - bilateral loss of pain and temp sensation

Affects corticospinal tracts - bilateral spastic paralysis, UMN signs

Dorsal columns unaffected as are posterior - so fine touch, proprioception and vibration sensation preserved

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34
Q

What occurs in posterior cord syndrome?

A

Bilateral damage to the dorsal columns, affects fine touch, proprioception, vibration sensation

Corticospinal tracts can be affected, spinothalamic tracts are spared

Often seen in subacute combined degeneration
As a result of B12 deficiency

35
Q

What is syringomyelia?

A

Central cord syndrome
Due to fluid filled cyst - syrinx around spinal canal

Associated with Chiari malformation

Decussating fibres first affected, then can expand and affect corticospinal and spinothalamic tracts

Upper limbs affected first, white matter fibres first to be compressed - cape like loss of pain and temp sensation

36
Q

What is spinal cord concussion?

A

Transient loss of spinal cord function, usually resolving within 48 hours

37
Q

What are the investigations for spinal cord lesions?

A 
FBC
U&Es
LFTs
B12
Inflammatory markers ESR or CRP
Antibody screens - aquaporin 4/MOG (neuromyelitis optica)

MRI spinal cord, full spine

Infective or autoimmune consider an LP

38
Q

What is a mononeuropathy?

A

Damage/dysfunction of a single peripheral nerve

Commonly due to entrapment or compression - internal e.g. tumour or external e.g. fracture, compressive clothing

39
Q

What is the organisation of the peripheral nervous system?

A

Visceral fibres - sensory fibres that carry info from thoracic and abdominal compartments, and motor fibres forming ANS (sympathetic and parasympathetic)

Somatic fibres - important sensory info from skin, muscles, bone, joints

Motor and sensory somatic fibres carried via spinal nerves and cranial nerves

40
Q

What are the three groups of mononeuropathies?

A

Cranial mononeuropathies - the 12 paired nerves arising from brain/brainstem

Upper limb

Lower limb

41
Q

What is the median nerve innervation to the hand?

A

Sensory to palmar and distal dorsal aspects of lateral three and a half digits and palm

Motor function - 
Pronator teres
Flexor carpi radialis
Palmaris longus
Flexor digitoris superficialis

Anterior interosseous - pronator quadratus, flexor pollicis longus, some of flexor digitorum profundus

LOAF - lumbricals, opponens pollicis, abductor pollicis brevis, flexor pollicis brevis

42
Q

What can cause median nerve neuropathy?

A

Carpal tunnel syndrome - compression when passes through carpal tunnel and flexor retinaculum/carpal bones

Compression due to haematoma, trauma or tumour

Pronator teres syndrome

Anterior interosseous nerve syndrome - cannot make the ok sign

43
Q

What are the risk factors for carpal tunnel syndrome?

A 
Diabetes
pregnancy
Rheumatoid arthritis
Obesity
Thyroid disease
44
Q

What are the features of median nerve neuropathy?

A

Sensory loss and/or paraesthesia over palmar/distal dorsal aspects of first 3 digits

Weakness/clumsiness using the hand

Weak thumb abduction

Thenar eminence wasting

Hand pain - typically worse at night

45
Q

What manoevres can be performed to elicit signs of median nerve neuropathy?

A

Phalen’s

Tinel’s non specific, tapping proximal to damaged nerve, pain or paraesthesia over distribution of the median nerve

46
Q

What is the anatomy of the ulnar nerve?

A

Continuation of medial cord of brachial C8-T1

Lies medial to brachial artery

At elbow, passes between medial epicondyle of humerus and olecranon of ulna

47
Q

What can cause compression of the ulnar nerve?

A

Cubital tunnel at the elbow

Guyon’s canal at the wrist

48
Q

What does the ulnar nerve innervate?

A

Sensory function to palmar and dorsal aspects of medial one and a half digits - little finger and medial side of ring finger

Flexor carpi ulnaris
Flexor digitorum profundus

Intrinsic muscles of the hand except for LOAF

49
Q

What are the clinical features of ulnar neuropathy?

A

Sensory loss and/or paraesthesia
Hand weakness, loss of dexterity, grip weakness
Muscle wasting - hypothenar eminence
Claw hand deformity - hand of benediction secondary to an ulnar neuropathy

50
Q

What is the presentation of radial neuropathy?

A

Acute wrist drop

Saturday night palsy

Sensory loss/paraesthesia over the dorsum of the hand
Weakness in finger extension
Weakness in brachioradialis

51
Q

What is the presentation of axillary neuropathy?

A

Most often due to trauma e.g. shoulder dislocation

Regimental badge sensory loss

Supplies deltoid, teres minor, lateral head of triceps brachii

52
Q

What is the presentation of common peroneal neuropathy?

A

Acute foot drop

Due to weakness of dorsiflexion

Commonly due to trauma/injury to the knee e.g. knee dislocation or from external compression

Sensory loss or paraesthesia over the dorsum of the foot and lateral shin

Weak dorsiflexion and eversion of the ankle

53
Q

What is the presentation of tibial neuropathy?

A

Due to compression as it passes under the transverse tarsal ligament - fracture or dislocation of the ankle, inflammatory arthritis, tumours

Paraesthesia, pain and numbness over the sole of the foot

Pes planus, pronated foot or abnormal gait (antalgic gait, excessive pronation)

54
Q

What are the investigations for mononeuropathies?

A

Electrodiagnostic testing

EMG - evaluates muscle units
NCS - evaluates peripheral nerves

Imaging - x-rays or CT, MRI if chronic

55
Q

How can polyneuropathies be classified?

A

Onset:
Acute - GBS, vasculitis, toxins, critical illness
Chronic - DM, CKD

Pathology:
Demyelination - autoimmune, hereditary
Axonal degeneration - DM, Vit B12 deficiency

Presentation:
Motor - weakness, atrophy e.g. GBC, CMTD
Sensory - DM, CKD

Small or large fibre

56
Q

What are some of the causes of polyneuropathy?

A

VITAMIN DC

Idiopathic
DM
Systemic illness
Autoimmune - GBS
Inflammatory - CIDP
Toxic - alcohol, chemo
Neoplastic - myeloma
Hereditary - CMTD
Nutritional - B12
Vasculitis
Medications - nitrofurantoin, isoniazid
57
Q

What are the investigations for polyneuropathies?

A

EMG testing
Nerve conduction studies

FBCs, U&Es, LFTs, Vits, myeloma screen, thyroid function, Hba1c, viruses, autoimmune, heavy metals, syphilis, Lyme’s

US, MRI, CT

Nerve biopsy, skin biopsy, autonomic testing, genetic testing

58
Q

What are two important tests of ulnar function?

A

Froment’s - pinch piece of paper between thumb and index finger, if there is flexion of distal phalanx of thumb - suggests ulnar weakness

Wartenberg’s - hold fingers fully extended, if little finger drifts away this is positive, due to weakness of ulnar innervated third palmar interosseous muscle

59
Q

What is the innervation from the radial nerve?

A

Sensory innervation for the dorsal aspect of the radial lateral three and a half digits

Triceps brachii
Extensor carpi radialis longus
Brachioradialis
Anconeus

Nerve passes through cubital tunnel into the forearm and continues as posterior interosseous nerve to innervate extensor muscles of forearm

60
Q

What is saturday night palsy?

A

Heavily inebriated and place arm over a chair, leads to compression

Can also occur due to haematoma, trauma, tumour, diabetes, vasculitis

61
Q

What is seen in isolated neuropathy of the posterior interosseous nerve?

A

Weak finger extension
Sparing of the proximal muscle groups
No sensory changes - it is a primary motor nerve

62
Q

What muscles does the axillary nerve innervate?

A

Deltoid
Teres minor
Lateral head of the triceps brachii

63
Q

What does the common peroneal nerve innervate?

A

Superficial peroneal nerve - anterolateral leg, lateral compartment of the leg
Deep peroneal nerve - first dorsal webspace, anterior compartment of the leg

64
Q

What is meralgia paraesthetica?

A

Neuropathy of the lateral femoral cutaneous nerve
Over anterolateral thigh

Entrapment under the inguinal ligament, due to diabetes, obesity, old

Pain, numbness, paraesthesia over the anterolateral thigh

Solely sensory nerve, so reduced pin prick sensation on clinical testing, absent motor signs

65
Q

What are the two major pathological mechanisms of polyneuropathy?

A

Demyelination - degeneration of the myelin sheath

Axonal degeneration - dying back phenomenon starts distally

66
Q

What are the clinical features of a polyneuropathy?

A

Glove and stocking distribution

Burning sensation
Paraesthesia
Sensory loss - touch, pain, temperature
Ataxia - poor coordination
Loss of light touch, vibration, proprioception

Weakness, absent reflexes, hypotonia, fasciculations, muscle atrophy, cramping

67
Q

What is the course of the oculomotor nerve?

A

Midbrain into subarachnoid space
To lateral wall of cavernous sinus
Divides into superior and inferior fibres in the superior orbital fissure

68
Q

What are the stages of the pupillary light reflex?

A

Light source detected by photoreceptors
Transmitted via optic nerve
Input from pre tectal nucleus transmitted to the Edinger Westphal nuclei
From EWN to ciliary ganglion
From short ciliary nerve to ipsilateral pupillary sphincter
Pupillary constriction

69
Q

What sort of lesions can cause a third nerve palsy?

A

Midbrain - tumour, haemorrhage, ischaemia

Subarachnoid space - inflammation, malignancy, ischaemia, aneurysm

Cavernous sinus - thrombosis, tumour, carotid artery aneurysm

70
Q

What does pupil sparing versus pupil involvement tell us about third nerve palsies?

A

Parasympathetic fibres are superficially within the nerve

Compressive lesions e.g. aneurysms affect outer fibres leading to pupillary dilatation, loss of light reflex

Vascular lesions inner fibres preferentially so are sparing

71
Q

What is a sixth nerve palsy?

A

Dysfunction of the abducens nerve, causing a lateral rectus palsy

72
Q

What is the difference in presentation of an isolated abducens palsy between adults and children?

A

Adults - ischaemic mononeuropathy e.g. diabetes, hypertension

Children - tumours, trauma, increase in ICP, congenital lesion

73
Q

What is the presentation of a sixth nerve palsy?

A

Failure in eye abduction leading to horizontal diplopia

Diplopia worse on horizontal gaze in direction of lesion

74
Q

What are the features of L1 radiculopathy?

A

Sensory changes in inguinal region

75
Q

What are the features of L2-L4 radiculopathy?

A

Acute back pain
Radiates down anterior thigh
Sensory changes over anterior thigh, medial lower leg
Weakness in hip flexion, knee extension, hip adduction

May have loss of knee reflex

76
Q

What are the features of L5 radiculopathy?

A

Acute back pain
Radiates down lateral aspect of foot
Weakness in foot dorsiflexion, big toe extension, foot inversion/eversion

77
Q

What are the features of S1 radiculopathy?

A

Acute back pain
Radiates down posterior aspect of leg into the foot
Sensory changes over posterior leg and lateral foot
Weakness in hip extension and knee flexion
May have loss of ankle reflex

78
Q

What manoeuvres can help determine if pain is radicular in origin?

A

Straight leg raise for L5/S1 radiculopathy

Reverse straight leg raise for L2-4 radiculopathy - worsening radicular pain on extending leg with patient prone

79
Q

What is sciatica?

A

Clinical manifestation of lumbosacral radiculopathies

Nerve roots L4, L5, S1, S2, S3

Pain radiates down posterior/lateral leg, to foot or ankle

80
Q

What is seen in C5 radiculopathy?

A

Neck pain, shoulder and scapula
Sensory loss on lateral upper arm
Weakness of shoulder abduction

81
Q

What is seen in C6 radiculopathy?

A

Neck pain, shoulder, scapula
Lateral arm, forearm, hand
Sensory loss in lateral forearm, thumb, finger (pointing a gun)
Weakness of elbow flexion, supination/pronation

82
Q

What is seen in C7 radiculopathy?

A

Neck pain, shoulder, hand, middle fingers
Sensory loss in palm, middle and index finger
Weakness in elbow and wrist extension
Triceps reflex affected

83
Q

What is seen in C8 radiculopathy?

A

Neck pain, shoulder, medial forearm, hand, 4th/5th fingers

Sensory loss in medial forearm, hand and 4/5th digits, weak finger movements

84
Q

What signs can suggest the involvement of the cervical cord?

A

Lhermitte phenomenon
Gait disturbance
UMN signs in the lower limbs - increased tone, weakness, clonus, upgoing plantars
Bladder/bowel dysfunction

Neuro & Special Senses (12 decks)

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