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Serum antibody tests ease of fatigue. These MG symptoms are usually
worsened across the day and after activities, which
AChR would be relieved after rest. In majority, ocular
muscle is the common and first victim.
For diagnosing MG with the specific antibodies,
positive results could be detected in about 50-60% Pharmacological response
patients with ptosis and other ocular sign, while
about 85-90% patients with generalized sign would Positive outcome in neostigmine test.
have positive outcomes. Based on also the medical
history of muscle weakness, positive diagnosis is EMG tests
enough to confirm MG. Further tests are needed if it
is a negative outcome. Ten percent decrement of CMAP and 2 or more
variable latency (> 55 ms) in SFEMG with or without
Anti-MuSK any blocks.

Anti-MuSK could be detected in some patients with Antibody tests
generalized sign of muscle weakness who have
negative outcomes in the test of AChR antibody, while Test of anti-AChR in blood sample of generalized form
other patients may present positive outcomes of low- of MG is positive. Anti-MuSK and LRP-4 would only
density LRP-4 antibody or other antibodies without be detected in some rare cases of MG.
known antigens at the neuromuscular junctions.
Negative outcomes could be due to the low levels With all clinical symptoms, and positive outcomes
or weak affinity of these antibodies, resulting in of pharmacological and electrophysiological tests, it
undetectable outcome. It should also be noted that can be diagnosed as MG. When it is available, blood
the ratio of anti-MuSK positive result in Western test of anti-AChR or other related antibodies could be
population is usually higher that that in Asian adopted for further confirmation. Furthermore, other
population. unknown diseases may interfere the diagnosis.

Anti-striated muscle antibodies Differential diagnoses
Ocular MG
Anti-striated muscle antibodies include anti-titin,
anti-RyR and etc. This type of antibodies is usually Miller-Fisher syndrome: it is a derivative of Guillain-
detected in those MG patients with severe signs, Barré syndrome, which is with acute paralysis
desensitization of conventional therapies of MG and of extraocular muscle, ataxia and loss of tendon
with also thymoma. This test is not for MG diagnosis reflexes. EMG results indicate there is delay of
but it strong indicates the opportunity of thymoma neurotransmission. Furthermore, in the analysis of
and other related transformations.
cerebrospinal fluid, there is protein-cell separation.
Thymus imaging In some cases, GQ1b antibody is detectable.
Chronic progressive external ophthalmoplegia
There are approximately 20-25% MG patients suffer
also from thymic tumors while 80% have abnormal (CPEO): CPEO is one of the mitochondrial myopathies,
condition of thymus. Amongst the MG patients patients of which experienced symmetrical, bilateral
with thymic tumors, 20-25% of them present MG and progressive ptosis, paralysis of extraocular
symptoms. Ninety-four percent thymic tumors could muscle, myogenic lesions and lactic acidosis. Some
[7]
be positive diagnosed by mediastinal CT. However, patients may experience also weakness of proximal
some cases are only diagnosed by advanced CT scan limbs and delay of peripheral nerve transmission.
or MRIs. Muscle biopsy and gene tests are needed for further
confirmation.
DIAGNOSIS
Oculopharyngeal muscular dystrophy (OPMD): OPMD
Bases of diagnosis is a progressive muscular dystrophy, the patients of
which experience progressive ptosis and weakness of
Clinical symptoms the extraocular muscles. There is also a slight elevation
of the serum level of creatine kinase. EMG diagnosis
There is patchy distribution of weakness on certain of OPMD shows myogenic lesion. Muscle biopsy and
particular striated muscle, exhibiting volatility and gene tests are needed for further confirmation.

Neuroimmunol Neuroinfammation | Volume 3 | Issue 1 | January 20, 2016 3