Peripheral Nerves Flashcards

Question

Upper Trunk Brachial Plexus injury

Answer 1

Loss of C5 and C6 Loss of shoulder movement Loss of elbow flexion "waiter's tip position" Sensory: lateral aspect of arm and forearm (musculocutaneous)

Answer 2

C8 - T1 Loss of everything in the hand Loss of sensation along medial aspect of hand and forearm Can get a Horner's syndrome because the sympathetic pathways come from C8-T1 too.

Answer 3

Hip Flexion Knee Extension (Quads) Sensation: medial aspect of thigh Loss of knee jerk

Answer 4

Knee flexion Plus distal movement Flaccid foot drop Loss of sensation below knee Loss of ankle jerk and plantar response

Answer 5

Posterior compartment Plantarflexion Ankle Inversion Loss of ankle jerk Sensory: most of sole of foot

Answer 6

Ankle eversion (Superficial peroneal) Dorsiflexion - foot drop (Deep peroneal) Sensory: Superficial: lateral aspect leg, dorsum of foot Deep: between 1st and 2nd toe

Answer 7

Gluteus Maximus - Hip extension

Answer 8

Hip Adductors

Answer 9

Hip Flexors

Answer 10

Knee Extensors

Answer 11

Ankle Dorsiflexion Inversion

Answer 12

Long toe extensors Inversion/eversion

Answer 13

Ankle plantar flexion Eversion

Answer 14

Count down joints Then around joints

Answer 15

L3 has addition to hip adduction weakness Otherwise: Knee extension weakness Hip flexion weakness Loss of Knee Jerk Sensation similar - down onto knee

Answer 16

Femoral Nerve L3 L4

Answer 17

Tibial Nerve S1 S2

Answer 18

L4/L5: loss of inversion/eversion, but jerk present Sciatic: everything gone Common peroneal: eversion gone, but jerk and inversion present (because tibial does this)

Answer 19

Small fibre nerves Pain and autonomic signals

Answer 20

Large Myelinated fibres record best Aids localisation Can't test small fibres or autonomic fibres Motor: anterior horn cell to muscle (Includes NMJ) Sensory: skin to dorsal root ganglia

Answer 21

Axonal loss

Answer 22

Demyelination Initial finding in compression is sensory CV slowing

Answer 23

Marker of demyelination

Answer 24

Signal goes wrong way up to anterior horn then bounces back, so can assess proximal segment of nerve May be the only abnormality in early GBS

Answer 25

Onset is subacute Proximal and Distal: AIDP, CIDP Asymmetric: Multifocal motor neuropathy, Mononeuritis multiplex Constitutional symptoms

Answer 26

Mycobacterium leprae Consider: low/middle income countries with skin lesions, cutaneous sensory loss, thick nerves on palpation, focal mononeuropathies Sparing of reflexes and dorsal columns Responsive to antibiotics

Answer 27

Mononeuritis Multiplex

Answer 28

Most commonly affected nerve in sarcoidosis Parotid swelling can also cause this, part of Heerfordt Syndrome with uveitis, transverse myelitis

Answer 29

Small fibre neuropathy is most common presentation for nerve involvement Bilateral CN VII is the key nerve involvement

Answer 30

Deletion of ch 17p11.2 containing PMP22 gene AD inheritance Predisposition to getting compressive neuropathies

Answer 31

Distal, symmetric, sensory neuropathy affecting small sensory fibres or both Posirtive and negative symptoms, most have pain Usually no motor symptoms Isoniazid exposure, advanced age increase risk

Answer 32

Sensory, motor and small fibre Axonal or demyelinating Anti Hu, Anti CV2

Answer 33

Genetic condition with peripheral neuropathy main manifestation. Insidious onset, can develop during infancy, can develop foot deformities. Lack of positive sensory symptoms despite clear sensory involvement. Loss of reflexes Loss of fine motor movement in hands is a late finding AD inheritance Demyelinating (CMT1): motor predominant AD inheritance Axonal (CMT2): sensory predominant Also X linked and AR forms

Answer 34

Broad spectrum of involvement, including small fibres and autonomic fibres. Even cranial nerves. Distal symmetric sensorimotor peripheral neuropathy, sensory predominant. Positive and negative symptoms. Positive and negative symptoms, including pain. Weakness unusual early.

Answer 35

Impacts morbidity and mortality T1DM > T2DM Increases with time Resting tachycardia, exercise intolerance, postural hypotension, gastroparesis, dry skin

Answer 36

Amitriptyline has lowest NNT Duloxetine, venlafaxine, gabapentin and pregabalin are other options.

Answer 37

Aensorimotor axonal length dependent neuropathy in majority Platinum based (platins): develop very quickly, within weeks. Due to binding to DNA inducing apoptosis. Taxanes (Paclitaxel, docetaxel) and Vinca alkaloids (Vincristine, vinblastine). Due to disruption of microtubules. Bortezomib (Proteasome inhibitor) That is frequently dose limiting

Answer 38

Vitamin B1 Vitamin B6 Vitamin B12 (subacute combined degeneration of dorsal column and spinocerebellar - UMN + proprioceptive loss) Vitamin E Copper Thiamine deficiency

Answer 39

Disc Herniation: lower of the two involved Vertebrae = involved nerve Foraminal stenosis: upper of the two involved vertebrae = involved nerve

Answer 40

Sensory studies normal Motor studies: normal or reduced amplitude EMG: neurogenic changes in affected myotome muscle groups (increased amplitude, polyphasia, decreased recruitment)

Answer 41

Remain active Don't give opioids or pregabalin Steroids variable Physiotherapy 33% resolve within 2 weeks, 90% in 3 months spontaneously Surgery may be helpful if pain persists past 4 months, unclear if improves weakness

Answer 42

AIDP Mean age of onset 40, M > F Humorally mediated disorder leading to TT lymphocyte infiltration and intense macrophage associated segmental demyelination in proximal nerve segments and nerve roots Antibodies Axonal subtype: GM1 GD1a Miller Fisher: GQ1b IgG and complement deposition Molecular mimicry with campylobacter jejuni can play a role Weakness predominant ascending pattern is most common but lots of others

Answer 43

Viral prodrome 1-2 weeks prior Ophthalmoplegia Loss of reflexes Ataxia GQ1b antibodies

Answer 44

Prodromal illness in 4 weeks prior in 60-70% of cases URTI and campylobacter jejuni most common Surgery, malignancy (esp. Hodgkin Lymphoma), pregnancy, mycoplasma pneumoniae, CMV, EBV, HIV, VZV, HBV/HCV, Zika Post immune checkpoint inhibitors

Answer 45

Albuminocytologic dissociation So markedly raised protein in CSF with normal or slightly raised white cell count May be delayed if taken early

Answer 46

Prolonged F wave latency Prolonged distal latencies/reduced velocity (motor before sensory) Conduction block Sural often preserved Sensitivity is poor early in disease

Answer 47

PLEx or IVIg PLEx: - Removes autoantibodies, immune complexes, cytokines - Needs to be given within 2-4 weeks - Reduces time to walk unaided by 32-41 days and time on ventilator by 2 weeks IVIg: - Benefit seen within 2 weeks in those unable to walk unaided - Repeat dosing at 4 weeks if slow improvement is not necessarily helpful No benefit of both Oral Steroids → worse outcome

Answer 48

Campylobacter jejuni CMV

Answer 49

Chronic version of AIDP, nadir past 4 weeks, usually progressive >8 weeks. Lower limb predominant, but similar pattern of proximal and distal weakness. Usually milder than AIDP NCS and LP findings similar Treat with steroids - Pulse MP 3 days, then monthly 1 day ongoing - Long term IVIg often required

Answer 50

Antibodies to the nodes and paranodal proteins. Atypical disease Specific antibodies Rituximab for management

Answer 51

Can present like AIDP, also as a cranial neuropathy Mechanism not fully understood CSF pleocytosis typical compared to AIDP/CIDP Treat with steroids

Answer 52

Older men Sensory ataxia, mild weakness Prolonged distal latency on NCS 50% have anti-MAG antibody Rituximab Can mimic CIDP - all with CIDP like presentation need paraproteins sent

Answer 53

Painful length dependent small fibre peripheral neuropathy with generalised autonomic failure Orthostatic hypotension common for ATTR, can use Inotersen (antisense oligonucleotide) and Patisiran (RNA interference agent)

Answer 54

Motor only components of peripheral nerves → asymmetric Upper limb predominant Decreased tendon reflexes in affected areas Investigations: - Serum anti-GM1 antibodies - Motor conduction block IVIg for management steroids can worsen

Answer 55

Think about dorsal root ganglionopathy

Answer 56

Radicular pain, paraesthesia, genital discomfort, lower extremity weakness. If conus or caua equina involved, urinary retention can occur. MRI: nerve root enlargement, T2 hyperintensity CSF: lymphocytic pleocytosis, high protein Aciclovir IV if immunocompromised Otherwise Valacyclovir

Answer 57

Severe pain in shoulder Vasculitis of brachial plexus Followed by weakness and atrophy of muscles of shoulder Mostly middle aged men Axonal loss as vessels infarct Recover well with steroids

Answer 58

New name for diabetic amyotrophy

Answer 59

- Weakness with no sensory symptoms - Fatiguability - Proximal symmetric weakness - Respiratory symptoms - Neck weakness

Answer 60

1 motor nerve fibre and all the muscle fibres it innervates Number of muscle fibres innervated by a single motor nerve fibre varies.

Answer 61

Abnormal Denervated fibres express ACh receptors along their entire length, which leads to spontaneous firing due to background levels of ACh Sign of active denervation Fibrillation and positive spark waves

Answer 62

Abnormal spontaneous firing of individual muscle fibres, sign of active denervation and inflammatory myopathies

Answer 63

Firing of part or all of a motor unit Can be normal (Classic group is doctors and medical students) Mostly abnormal however and occur when there are sick or dying axons - MND - CIDP - Chronic nerve entrapments

Answer 64

- Broad and polyphasic morphology as there muscle axons are messy - Also increased amplitude because more muscles fibres firing from the same muscle axon - Reduced recruitment with maximum contraction as fewer motor units

Answer 65

Smaller amplitude as fewer fibres in each motor unit so smaller signal Increased or early recruitment as need lots of motor units for same force

Answer 66

- Lambert Eaton Myasthenic Syndrome (Voltage gated calcium channel disorder) - Botulism (vesicle problem)

Answer 67

Myasthenia Gravis (Ab against ACh receptors) Organophosphate poisoning (Acetylcholinesterase problem)

Answer 68

Ocular symptoms: Ptosis, diplopia Can mimic just about anything Generalised weakness, fluctuating and fatiguable Bulbar weakness, neck weakness, limb girdle, respiratory weakness. Check accomodation

Answer 69

- Ice test - Check for antibodies: AChR (85%), MuSK (6-10%) - Single nerve fibre (good for ocular) and repetitive nerve stimulation (10% decrement diagnostic - good for general) - Tensilon test (Edrophonium administration) - Hold eyes up, double vision occurs

Answer 70

15% of patients have isolated ocular myasthenia (although often the presenting symptom of generalised) 50% AChR Ab positive 66% will progress to generalised within 2 years 90% who don't generalise within 2 years remain ocular

Answer 71

IgG4 disease, non complement activating. Receptors not destroyed and thus respond quite well to Rituximab Early onset, severe disease. Not related to thymoma

Answer 72

Remove Thymoma if present (unless MuSK Ab) Cholinesterase inhibitors: Pyridostigmine Steroids: reduce risk of developing generalised MG, however can worsen before improving if give too much AZA, MMF, Tac, MTX IVIg, PLEx as rescue therapy Evidence for Rituximab as a single dose for new onset AChR+ve disease

Answer 73

Eculizumab, Ravulizumab, zilucoplan Used for generalised AChR+ moderate severity disease who've already had some form of immunosuppression which they've failed. Need meningococcal vaccine prior Works rapidly

Answer 74

Neonatal Fc Receptor molecule recycles IgG, extending half life. Keeps IgG around, and thus maintains availability of IgGZ autoantibodies in IgG mediated disease Efgartimod and Rozanolixizumab are human IgG1 Ab Fc-fragment, with higher affinity to the FcRn → outcompetes endogenous IgG → Pathogenic IgG degraded Improves outcomes. IVIg is essentially a blunt tool to overwhelm FcRn. More expensive.

Answer 75

Thymoma should be removed. Thymic hyperplasia should be removed if ACHr+ generalised disease. Lower disease scores Lower pred requirement Fewer patients on AZA Fewer admissions Fewer immunosuppression side effects

Answer 76

Severe respiratory weakness due to fatigue Treatment - Intubate - IVIg - PLEx - Supportive Care - Immunosuppression 5% mortality

Answer 77

Aminoglycosides Fluoroquinolones Tetracyclines Macrolides Beta blockers CCB (Verapamil) Phenytoin Lithium

Answer 78

NOn paraneoplastic Lambert Eaton

Answer 79

Lambert Eaton Myasthenic Syndrome

Answer 80

NCS: Attentuated CMAP without muscle mass loss, increases post exercise EMG: abnormal VGCC Ab positive in 90-100% of patients Malignancy screen

Answer 81

- Tumour resection if present - 3-4-diaminopyridine: blocks efflux of potassium ions, prolonging depolarisation (as disease is due to problems with calcium channels) - Immunosuppression, IVIg

Answer 82

Blocks presynaptic Acetylcholine release

Answer 83

2 day incubation Starts in eyes and descends Symmetric descending flaccid paralysis Autonomic symptoms Internal and external ophthalmoplegia (fixed pupils) Reflexes and cognition preserved

Answer 84

- Avoid aminoglycosides - Remove unabsorbed toxin if appropriate, e.g. ileus - Equine trivalent (A, B, E) antitoxin: lowers mortality, shortens course of illness. Stabilises but doesn't reverse disease Recover over months, but some symptoms can persist for years.