The diagnostic criteria were as follows: [sup] Extraocular muscle weakness in one or both eyes, ptosis or double vision, and remission after rest and severe fatigue at the initiation of the symptoms; fatigue of the affected muscle with fatigue test; a positive neostigmine test; or abnormal repetitive nerve stimulation (RNS) electromyography with a minimum decrement of 15% in extremities muscles and 10% in facial muscles; or abnormal serum acetylcholine receptor antibody (AchRab) level.
AchRab titer was measured by enzyme-linked immune-sorbent assay according to Lindstrom's method [sup] before January 2013, P/N (patient's optical density [OD]/normal control's OD) ≥1.2 was abnormal.
The AchRab titer was tested in all patients and was elevated in 48 (47.1%) patients.
There were no correlations between OMG prognosis and SFEMG abnormality, RNS abnormality, AchRab abnormality, or onset age [ P = 0.140, 0.150, 0.070, and 0.120, respectively, [Table 3].
Men predominated in the elderly group, with nine men and four women, 11 of the 13 were AchRab positive.
Acetylcholine receptor antibody study: The age distribution of the positive AchRab samples received at the supraregional immunology laboratory at Heartlands Hospital, Birmingham, was studied over two separate periods during this 7-year study, first in 1991 and then in 1994.
The use of the AchRab as an epidemiological aid seems suitable in MG for three reasons.
The presence of both receptor subtypes (a feature not found in conventional AChRAb
assays) increases the diagnostic sensitivity of the assay, as certain patient sera may preferentially bind to the mature receptor type.
The presence of both receptor subtypes ( a feature not found in conventional AChRAb
assays) increases the diagnostic sensitivity of the assay as certain patient sera may preferentially bind to the mature receptor type.