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Neuropathies and Spinal Cord Lesions Flashcards

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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
What are the types of ascending tracts?
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
26
Where do the nerve fibres cross in the spinothalamic tract?
At the anterior grey commissure at the level of the spinal nerve
27
How can you clinically assess the ascending tracts?
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
28
What are some of the signs that the lesion is within the spinal cord?
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
29
What are the signs of autonomic dysreflexia?
``` Hypertension Bradycardia Urinary retention Constipation Sweating Flushing above level of the lesion ```
30
What signs can help suggest where in the spinal cord is the problem?
If all four limbs - likely cervical If only lower limbs - thoracic Respiratory difficulties and diaphragm affected - avoe C3
31
What occurs in complete transection?
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
32
What is seen in Brown-Sequard syndrome?
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
33
What is seen in anterior cord syndrome?
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
34
What occurs in posterior cord syndrome?
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
What is syringomyelia?
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
What is spinal cord concussion?
Transient loss of spinal cord function, usually resolving within 48 hours
37
What are the investigations for spinal cord lesions?
``` 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
What is a mononeuropathy?
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
What is the organisation of the peripheral nervous system?
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
What are the three groups of mononeuropathies?
Cranial mononeuropathies - the 12 paired nerves arising from brain/brainstem Upper limb Lower limb
41
What is the median nerve innervation to the hand?
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
What can cause median nerve neuropathy?
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
What are the risk factors for carpal tunnel syndrome?
``` Diabetes pregnancy Rheumatoid arthritis Obesity Thyroid disease ```
44
What are the features of median nerve neuropathy?
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
What manoevres can be performed to elicit signs of median nerve neuropathy?
Phalen's Tinel's non specific, tapping proximal to damaged nerve, pain or paraesthesia over distribution of the median nerve
46
What is the anatomy of the ulnar nerve?
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
What can cause compression of the ulnar nerve?
Cubital tunnel at the elbow | Guyon's canal at the wrist
48
What does the ulnar nerve innervate?
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
What are the clinical features of ulnar neuropathy?
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
What is the presentation of radial neuropathy?
Acute wrist drop Saturday night palsy Sensory loss/paraesthesia over the dorsum of the hand Weakness in finger extension Weakness in brachioradialis
51
What is the presentation of axillary neuropathy?
Most often due to trauma e.g. shoulder dislocation Regimental badge sensory loss Supplies deltoid, teres minor, lateral head of triceps brachii
52
What is the presentation of common peroneal neuropathy?
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
What is the presentation of tibial neuropathy?
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
What are the investigations for mononeuropathies?
Electrodiagnostic testing EMG - evaluates muscle units NCS - evaluates peripheral nerves Imaging - x-rays or CT, MRI if chronic
55
How can polyneuropathies be classified?
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
What are some of the causes of polyneuropathy?
VITAMIN DC ``` Idiopathic DM Systemic illness Autoimmune - GBS Inflammatory - CIDP Toxic - alcohol, chemo Neoplastic - myeloma Hereditary - CMTD Nutritional - B12 Vasculitis Medications - nitrofurantoin, isoniazid ```
57
What are the investigations for polyneuropathies?
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
What are two important tests of ulnar function?
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
What is the innervation from the radial nerve?
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
What is saturday night palsy?
Heavily inebriated and place arm over a chair, leads to compression Can also occur due to haematoma, trauma, tumour, diabetes, vasculitis
61
What is seen in isolated neuropathy of the posterior interosseous nerve?
Weak finger extension Sparing of the proximal muscle groups No sensory changes - it is a primary motor nerve
62
What muscles does the axillary nerve innervate?
Deltoid Teres minor Lateral head of the triceps brachii
63
What does the common peroneal nerve innervate?
Superficial peroneal nerve - anterolateral leg, lateral compartment of the leg Deep peroneal nerve - first dorsal webspace, anterior compartment of the leg
64
What is meralgia paraesthetica?
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
What are the two major pathological mechanisms of polyneuropathy?
Demyelination - degeneration of the myelin sheath | Axonal degeneration - dying back phenomenon starts distally
66
What are the clinical features of a polyneuropathy?
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
What is the course of the oculomotor nerve?
Midbrain into subarachnoid space To lateral wall of cavernous sinus Divides into superior and inferior fibres in the superior orbital fissure
68
What are the stages of the pupillary light reflex?
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
What sort of lesions can cause a third nerve palsy?
Midbrain - tumour, haemorrhage, ischaemia Subarachnoid space - inflammation, malignancy, ischaemia, aneurysm Cavernous sinus - thrombosis, tumour, carotid artery aneurysm
70
What does pupil sparing versus pupil involvement tell us about third nerve palsies?
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
What is a sixth nerve palsy?
Dysfunction of the abducens nerve, causing a lateral rectus palsy
72
What is the difference in presentation of an isolated abducens palsy between adults and children?
Adults - ischaemic mononeuropathy e.g. diabetes, hypertension Children - tumours, trauma, increase in ICP, congenital lesion
73
What is the presentation of a sixth nerve palsy?
Failure in eye abduction leading to horizontal diplopia Diplopia worse on horizontal gaze in direction of lesion
74
What are the features of L1 radiculopathy?
Sensory changes in inguinal region
75
What are the features of L2-L4 radiculopathy?
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
What are the features of L5 radiculopathy?
Acute back pain Radiates down lateral aspect of foot Weakness in foot dorsiflexion, big toe extension, foot inversion/eversion
77
What are the features of S1 radiculopathy?
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
What manoeuvres can help determine if pain is radicular in origin?
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
What is sciatica?
Clinical manifestation of lumbosacral radiculopathies Nerve roots L4, L5, S1, S2, S3 Pain radiates down posterior/lateral leg, to foot or ankle
80
What is seen in C5 radiculopathy?
Neck pain, shoulder and scapula Sensory loss on lateral upper arm Weakness of shoulder abduction
81
What is seen in C6 radiculopathy?
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
What is seen in C7 radiculopathy?
Neck pain, shoulder, hand, middle fingers Sensory loss in palm, middle and index finger Weakness in elbow and wrist extension Triceps reflex affected
83
What is seen in C8 radiculopathy?
Neck pain, shoulder, medial forearm, hand, 4th/5th fingers | Sensory loss in medial forearm, hand and 4/5th digits, weak finger movements
84
What signs can suggest the involvement of the cervical cord?
Lhermitte phenomenon Gait disturbance UMN signs in the lower limbs - increased tone, weakness, clonus, upgoing plantars Bladder/bowel dysfunction

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