This document describes several classification systems for analyzing electromyography (EMG) results: 1. It classifies the degree of acute or subacute denervation seen on EMG as slight, moderate, or severe based on the duration of symptoms and EMG findings like fibrillation potentials and insertional activity. 2. It provides criteria for possible, probable, or definite myopathy based on spontaneous activity, motor unit potential morphology and instability, and involvement of muscle groups on EMG. 3. It outlines a quantitative EMG scoring system for evaluating myopathic changes with criteria in several categories. 4. It proposes a grading system for axonal and demyelinating peripheral neuropathy based

1. Classification of EMG in de-reinnervation
Stålberg et al, Computer Methods and Programs in Biomedicine, 34 (1991) 219-227
fibs ampl dur IP jiggle
slight acute 1-3 normal normal normal - ↓ normal -↑
mod acute 3-5 normal normal normal - ↓↓ normal -↑
severe acute 5-10 normal normal normal - ↓↓↓ normal -↑
slight subacute 1-3 ↑ Normal -↑ normal - ↓ normal -↑
mod subacute 3-5 ↑ ↑ ↓-↓↓ ↑-↑↑
sev subacute 5-10 normal normal ↓↓↓ ↑-↑↑
slight inactive 0-1 ↑↑ ↑ normal - ↓ normal
mod inactive 0-1 ↑↑ ↑↑ ↓-↓↓ normal -↑
sev inactive 0-3 ↑↑ ↑↑ ↓↓↓ normal -↑
acute = 7-30 days after onset
subacute > 30 days, combined de- reinnervation
inactive > 1 year after incident, non-progressive primary neuropathy

2. Myopathy Visual EMG scoring
Feature Possible Probable Definite
spont act fibs,psw +/- fibs psw +-++ fibs,psw +-+++
shape increased poly 30-50% poly dominance of poly
MUP smallish definitely small > 50% small MUPs
MUP instability jiggle +/- jiggle + jiggle ++
IP some areas MYO many areas MYO all areas MYO
Recruitment normal or early prob early def early
Myopathy QEMG scoring
Feature Possible Probable Definite
spont act 0-2 sites fib,psw 3-7/10 fibs,psw 8-10 /10 fibs,psw
shape poly 20-50% 50% poly > 50% poly
MUP 1-4/20outliers > 5/20 outliers or
abnormal mean
> 10/20 outliers, abnormal
mean
MUP instability jiggle +/- jiggle + jiggle ++
IP (T/A) 3-4 outliers 5-10 outliers, low mean
ampl
> 10/10 outliers
Recruitment RF 9-12 RF < 8 difficult to assess
all required
supportive Stålberg ,Falck 2103 non-published
Classification of
myopathic changes
in EMG
concerning
likelihood of
myopathy
(not grading of the
myopathy)
Very difficult, depends on
type and severity of the
myopathy

3. Grading of axonal and demyelinating pnp
without conduction block (unpublished Falck,Stålberg)
Sensory pnp
mild moderate severe very severe
ampl CV ampl CV ampl CV ampl CV
superf. fib ↓ /0 n/↓ 0 0 0
sural n n/↓ ↓ n/↓ 0 0
radial n n/↓ n/↓ n ↓ ↓n 0
Motor pnp
mild moderate severe very severe
ampl CV F ampl CV F ampl CV F ampl CV F
fibular n/↓ n/↓ n/abn n/↓ n/↓ abn 0 0
tibial n/↓ n/↓ n/abn n/↓ n/↓ abn 0 0
median n/↓ n n n n n n/↓ n/↓ abn 0
ulnar n/↓ n n n n n n/↓ n/↓ abn 0