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

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.

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)537-44.

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.

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

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

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

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:

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

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

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

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.