Brief Alerts: Early Diagnosis of Guillain-Barré Syndrome
August 1, 2001
Brief Alerts
Early Diagnosis of Guillain-Barré Syndrome
Source: Gordon PH, Wilbourn AJ. Early electrodiagnostic findings in Guillain-Barré syndrome. Arch Neurol. 2001;58: 913-917.
Objective laboratory evidence is of significant benefit in supporting a clinical impression of Guillain-Barré syndrome (GBS). Unfortunately, cytoalbuminogenic dissociation, the hallmark of GBS, is normal in 34% within the first week. Alternative avenues to support the diagnosis include nerve conduction studies (NCS) but such abnormalities are often similarly belated. When is the soonest GBS may be diagnosed electrodiagnostically and what are the earliest NCS abnormalities found?
A retrospective review of discharge diagnoses from the Cleveland Clinic in Cleveland, Ohio, covering the past 16 years revealed 31 GBS patients who underwent NCS in the first week of symptom onset. The more frequent abnormalities are tabulated in the Table below.
| Table: Frequent Abnormalities of GBS | |
| Abnormality | Frequency (%) |
| H reflex absent | 30/31 (97) |
| F wave (arm) absent | 17/31 (55) |
| F wave (leg) absent | 19/31 (61) |
| Motor amplitude low | 22/31 (71) |
| Motor amplitude low > 1 nerve | 19/31 (61) |
| Prolonged distal motor latency | 19/31 (61) |
| Slow conduction velocity | 16/31 (52) |
| Temporal dispersion | 18/31 (58) |
| Sensory response absent (arm) | 12/31 (39) |
| Absent sural sensory response | 5/31 (16) |
Late responses (H reflex and F waves) are the earliest and most sensitive NCS abnormalities in GBS but, even with multiple nerve testing, diagnosis is possible in only half, and not before day 5.
Commentary
Late response abnormalities, when occurring early, underscore the vulnerability of proximal nerve segments to demyelination, while the distal portions more commonly studied remain normal (Ann Neurol. 1978;35:344-350). Early diagnosis remains challenging. Up to 20% of GBS patients will demonstrate normal NCS during the first 2 weeks (Eisen A, Humphreys P. Arch Neurol. 1974;30:438-443; Arch Neurol. 1975;32:524-529). —Michael Rubin