1. Erb point in early diagnosis of Guillain-Barre syndrome in children
Sun Rui-Di
Department of Neurophysiology
WuHan children Hosptial

2. Guillain-Barre syndrome
autoimmune disease
peripheral nervous system
Nerve conduction: serial tests can classify the subtye of GBS
The examination time: two weeks from the onset of disease
Proximal nerve were the earliest affect place
The newly technology aim at detect proximal nerve funtion
Erb’s point is a site at the brachial plexus located 2–3 cm above the clavicle
reflect the condition of proximal nerves.

3. Patients and methods
Fulfilled the clinical criteria for GBS [1] :Mostly symmetric pattern of limb and/or motor cranial-nerve weakness, Monophasic disease course with
interval between onset and nadir of weakness of 12 h to 28 days, Cerebrospinal fluid albuminocytological dissociation
The first electrophysiological examination was performed within 1 week of illness onset.
1 Wakerley BR,Uncini A,Yuki N ,et al, Guillain–Barré and Miller Fisher syndromes—new diagnostic classification[J].Nat Rev Neurol,2014,10(9)

4. The patient had two electrophysiological examination: conventional conduction (motor and sensory nerve),F wave latency,erb stimulation
Subtype of GBS is AIDP [2] (acute inflammatory demyelinating polyneuropathy)
[2] Hadden RDM, Cornblath DR, Hughes RAC, . Electrophysiological classification of Guillain-Barré syndrome: clinical associations and outcome.1998;44:780–8.

5. Table 1 compartive of ulnar nerve in CMAP and DML
CMAP= compound muscle action potential
DML= distal motor latency
group n
Wrist CMAP(mv)
Elbow
CMAP(mv )
Erb CMAP(mv)
Wrist DML(uv)
Elbow DML(uv)
Erb DML(ms)
Control group 30
8.2±1.9
7.6±1.7
7.8±2.0
2.5±0.3
5.0±0.6
9.7±0.5
Patients group 32
7.7±2.5
7.1±2.7
4.3±2.5
2.8±0.7
5.5±1.3
10.8±1.7 t
0.67
0.63
4.56
-1.83
-1.49
-2.83 p
0.51
0.53
<0.01
0.08
0.15

6. Table 2 compartive of median nerve in CMAP and DML
CMAP= compound muscle action potential
DML= distal motor latency
group n
Wrist CMAP(mv)
Elbow
CMAP(mv )
Erb CMAP(mv)
Wrist DML(uv)
Elbow DML(uv)
Erb DML(ms)
Control group 30
7.3±1.7
7.0±1.5
6.7±1.5
2.5±0.6
5.6±0.5
9.4±0.5
Patients group 32
6.9±2.2
6.5±2.2
4.6±2.3
2.8±0.8
5.6±1.4
10.9±1.6 t
0.66
0.88
3.25
-0.97
-1.24
-4.28 p
0.52
0.38
<0.01
0.34
0.23

7. F waves minimal latency was abnormal in 23 patients(72%)
Prolong latency in Erb point were seen in 24 patients(75%)

8. Discussion AIDP is main subtype in GBS
Electrophysiology in AIDP: a partial motor CB, pro-
longed distal motor, H reflex and F wave latencies, lower CMAP
F wave latency is sensitivity in early stage of GBS,
But demyelination at a small part of the nerve may not be detected by F wave latency measurement.
Picture:

10. Erb point is near proximal nerve
It can detect proximal nerve function
Picure:

11. Other technology:
Median nerve ssep: N9,N13 latency
N9- Erb point ,N13-C6 point represent proximal nerve function

15. GBS has proxiaml nerve affected as well as CIDP
SSEP utility in early GBS.
Somatosensory Evoked Potentials and Nerve Conduction Studies in Patients with Guillain-Barre Syndrome
Jiri Vajsar, MD, Margot J Taylor, PhD, Lynn J MacMillan, RN, E Gordon Murphy, MD and William J Logan, MD

16. Conclusion Erb point near the proximal nerve
It can represent proximal nerve function when pathy demyelinatine in proximal nerve at early stage of disease.
Limit:Erb point stimulation can not be detect when the patient is fat
New technology: ssep can detect both erb point and lower cervical spinal which can provide more evidence about proxiaml nerve in CIDP and GBS.