EDx patterns in nonfocal disorders

1
EDx patterns in non-focal disorders

• W Mak
• NDU, QMH

2
Non-focal disorders

• Demyelinating neuropathies
• Axonal neuropathies (MND)
• Paraneoplastic neuropathies
• Vasculitic neuropathies
• HMSN HNPP
• Kennedys Disease
• Myopathies
• CMA syndromes

3
Demyelinating neuropathies 1

• EDx criteria

4
Demyelinating neuropathies 2
5
Demyelinating neuropathies 3

• Motor conduction block
• gt 50 ? cMAP amplitude with lt15 ? duration
• gt 50 ? cMAP area
• gt 30 ? cMAP amplitude / area if short segment
• ( 20 50 for M, U, P)
• AANEM criteria for partial CB
• Dispersion

6
Demyelinating neuropathies 4

• Patchy or multifocal involvement
• BNB
• Relatively normal sural
• Conduction block, refractory nerves
• Evolving changes (GBS, CIDP)
• Prognosis.

7
Demyelinating neuropathies 5

• Mixed demyelinating axonal PN
• For sural nerve Bx
• For clinical correlation.

• Pitfalls

8
Axonal neuropathies 1

• Relevance of a protocol
• 3Os Old, obese, oedema
• Advanced axonal neuropathies
• Needle EMG examination (EDB).

9
Axonal neuropathies 2

• Motor neuron disease
• Active denervational changes
• Reinnervational changes
• Fasciculations
• SFEMG
• dDx - MFMN

10
Axonal neuropathies 2

• Motor
• MFMN, MND, SMA, Pb, porphyria, dapsone, polio
• Sensory
• cisplatin, paraneoplastic, Sjö, B6, thalidomide,
  SAN
• Small fibre
• Leprosy, FAP, DM, anti-AIDS
• Autonomic
• DM, FAP, paraneoplastic, GBS, Riley-Day.

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Paraneoplastic neuropathies

• Sensory neuronopathy
• Distal sensorimotor neuropathy
• Demyelinating neuropathy

12
Vasculitic neuropathies 1

• Acute deep aching pain neuropathic pain
• Watershed zone infarction (e.g., mid-thigh for
  peroneal, mid-upper arm for ulnar)
• CP gt PT / U gt M gt R
• PAN gt RA gt Sjögrens gt SLE gt WG
• (non-systemic 1/3)

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Vasculitic neuropathies 2

• PAN 44 62
• Sjögrens 10 20
• SLE 3 18
• Giant cell arteritis 14
• Scleroderma 14
• MCTD 10
• RA 1 10 (40 50)

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Vasculitic neuropathies 3

• Spectrum of neuropathies in CTD
• MNM, asym PN, confluent MNM
• Autonomic neuropathy / dysfunction
• Distal axonal PN, not clearly vasculitic
• Entrapment neuropathies
• Sensory neuronopathy
• Trigeminal sensory neuropathy
• Others AIDP, CIDP

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Vasculitic neuropathies 4

• Patterns of vasculitic neuropathies
• MNM 57
• Asym PN 12
• Distal sym 32
• Evolves as a confluencing process

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Vasculitic neuropathies 5

• EDx of MNM
• Significant difference in amplitude of same nerve
  at different limbs
• Decreased amplitude in one nerve but not in
  another of the same limb
• Decreased amplitude for UL nerves, but not for LL
  nerves
• CB ? WD

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HMSN

• Crude classificataion
• HMSN 1
• HMSN 2
• HMSN 3
• HMSN X
• HNPP

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HNPP 1

• Diffuse motor and sensory conduction
  abnormalities multifocal neuropathy occurring
  predominantly at usual sites of entrapment
• 1.5 mega-base deletion 17p11.2
• PMP-22 gene
• Reported in other phenotypes (CMT 1A)
• Point mutation in PMP-22 in some families

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HNPP 2

• Sites of acute nerve palsies
• Peroneal gt Ulnar gt Brachial plexus gt Radial gt
  Median
• Pes cavus 17 22

20
HNPP 3

• Bilateral CTS
• Mildly prolonged ulnar DSL DML
• Bilateral UN-E
• Attenuated sural SNAPs
• Mildly prolonged DML at EDBs and AHs
• Slowing of peroneal MMCV
• PN-K is uncommon.

21
HNPP 4

• Genetic studies
• Family screening
• Children Abnormal values for age in distribution
  similar to adults

22
Kennedys disease

• X-linked bulbospinal muscular atrophy
• Middle-age
• Proximal weakness
• Attenuated sural
• Denervation/reinnervation at proximal, facial
  bulbar muscles
• MCV involvement - advanced

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Myopathies 1

• Myonecrotic inflammatory
• Bland
• Specific
• Myotonic syndromes
• McArdles (fibs, electric-silent cramps)
• Acid maltase def (PS fibs, PSW, CRD )
• IBM
• Statin, colchicine

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Myopathies 2

• Myopathy neuropathy
• Mitochondrial, paraneoplastic, C2H5OH,
  colchicine, sarcoid
• Myopathy CNS
• DMD, MyoD, mitochondrial, thyroid
• Myopathy pain
• Myositis, CTD, rhabdo, infection
• Myopathy resp failure
• Acid maltase, PM (Jo1), congenital myopathy, DMD.

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CMA syndromes 1

• Myotonia
• Myokymia
• Neuromyotonia
• Sustained MUAP firing
• EMG criteria vs clinical description

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CMA syndromes 2

• CNS Stiff-person-syndrome, rigidity
• Tremor
• Radiation / MS-induced myokymia
• PNS Issacs syndrome ( PN)
• Tetany
• Raditation-induced myokymia
• Muscle Myotinia, paramyotonia

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CMA syndromes 3

• Myotonia
• Clinical
• Delayed relaxation propagated electrical
  activity (myotonic discharge, neuromyotonic
  discharge, CRD)

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CMA syndromes 4

• Myotonic discharge
• Repetitive discharge 20 80 Hz
• Biphasic spikes or positive waves
• Induced by needle movements
• Wax and wane amplitude and frequency
• No spontaneous muscle spasms or stiffness at rest

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CMA syndromes 5

• Cooling (to 20?C)
• Myotonia ?,
• ParaMyo ??, several hr to recovery
• Exercise
• cMAP ?, recovery lt2 90 min
• Distal myopathy.

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Myotonia syndromes

• MyoD
• PROMM
• Early adulthood, proximal weakness
• Myotonia congenita
• Dominant (Thomsen), infant
• Recessive (Becker), late childhood
• Paramyotonia congenita
• Early onset, assoc. HyperK-PP

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CMA syndromes 6

• Complex repetitive discharge
• Repetitive polyphasic / serrated MUAPs, 5 100
  Hz
• Spontaneous or with needle movements
• Uniform shape, frequency, amplitude
• Abrupt onset and cessation
• Hyperexcitable muscle membrane (PS, IL)
• Assoc fibs / PSWs

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CMA syndromes 7

• Myokymia
• Continuous undulating movement at surface (skin,
  mucous membrane)
• Myokymic discharge, neuromyotonic discharge,
  continuous fasciculation

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CMA syndromes 8

• Myokymic discharge
• Repetitively firing MUAPS
• Pattern 1 Transient firing in groups (rate of 2
  60 Hz), interrupted
• Pattern 2 Continuous at fairly uniform firing
  rate (1 5 Hz)

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CMA syndromes 9

• Neuromyotonia
• Clinical syndrome, manifesting as continuous
  muscle rippling and stiffness
• Loose label of hyperexcitable PNS disorders
  (neuromyotonic discharge, myokymia,
  fasciculations)

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CMA syndromes 10

• Neuromyotonic discharge
• Bursts of MUAPs, in doublets / triplets / single
  units, at rate of 150 300 Hz
• Few seconds, starts and stops abruptly
• Descrescendo amplitude and frequency
• Persists during sleep
• Issacs syndrome ( myokymic discharge,
  fasciculations, PN)

37
CMA syndromes 11
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CMA syndromes 12

• Myotonic discharge
• Dive-bomber
• Myokymic discharge
• Marching soldiers
• Complex repetitive discharge
• Speedboat/motorbike
• Neuromyotonic discharge
• Muscial sound piiiiinnnnnnggg

39
Colchicine myopathy

• Clinical
• Predisposition
• Axonal neuropathy
• Fibs, PSWs and CMA .

40
Miscellaneous techniques

• W Mak
• NDU, QMH

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Miscellaneous techniques

• Thermal-detection thresholds
• Sympathetic skin response
• Blink reflex
• Other facial nerve techniques
• Short-segment studies
• H-reflex
• Diaphragmatic study

42
Thermal detection threshold

• Cold-detection threshold
• Warmth-detection threshold
• Method of limits
• Method of levels (forced choice)

43
Thermal detection threshold

• Hand
• Warmth detection threshold 2.4,
• Cool detection threshold 1.9,
• Difference 4.3
• Foot
• Warmth detection threshold 5.9,
• Cool detection threshold 3.0,
• Difference 7.2

44
Thermal detection threshold

• Body parts, age
• Semi-quantitative, subjective reporting
• Not specific for small fibres
• Reaction time (method of limits)
• Heat-induced pain 46
• Cold-induced pain

45
Sympathetic skin response
46
Sympathetic skin response

• Detecting sudomotor discharges
• Deep breath
• Startle
• Electric shock
• Presence/absence (all-or-none)
• Consistency
• Latency and amplitude

47
Short-segment studies

• 10 cm rule

48
Blink reflex

• R1 ipsilateral
• R2 ipsi contra-lateral
• R1 gt13, R2 gt41
• R-L difference
• R1 gt1.5, R2 gt10
• D-C diff, R2 gt5

49
Blink reflex
Rt
Rt Vn
Lt
Rt VIIn
Rt
Lt
50
Blink reflex
Rt
Rt Vn
Lt
Rt lateral medulla
Rt
Lt
51
Blink reflex
Rt
Rt Vn
Lt
Rt Pons
Rt
Lt
52
Other facial nerve techniques

• Facial nerve MNC
• DML lt 4.5
• R-L diff lt 20
• Facial nerve excitability
• 0.6 1 msec, normal 3 8 mA
• R-L diff gt 4mA
• gt 20 mA
• Facial synkinesia

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H-reflex
54
H-reflex (soleus)

• Presence / absence
• Latency, amplitude
• Refractory H
• Not specific for S1 radiculopathy

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H-reflex (FCR)

• Latency lt 17

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H-reflex (FCR)
57
Diaphragmatic studies

• Diaphragm EMG
• Phrenic nerve stimulation
• DML lt8