Occurrence of CNS demyelinating disease in patients with myasthenia gravis
IlyaKister, NYU/Hospital for Joint Diseases, 301 East 17th Sreet, Suite 550, New York, NY 10003ilya.kister@mssm.edu
Joseph Herbert, Michael L. Swerdlow, Roberto Bergamaschi, Giovanni Piccolo and Joel Oger
Submitted December 04, 2006
Gotkine et al [1] describe three patients with
myasthenia gravis (MG) who underwent thymectomy and subsequently developed
either recurrent or monophasic acute myelitis. The authors suggest that
these patients may have a "form fruste of SLE", given their elevated ANA
titers, though they have not exhibited any non-neurologic manifestations
of SLE and had no anti-ds DNA Ab in serum.
Alternatively, we would like to
propose that the three patients may have form fruste of Neuromyelitis Optica
(NMO). ANA positivity is not an infrequent finding in NMO [8] and would
not preclude this diagnosis. All three patients had extensile cord lesions three
or more vertebral segments in length, which are highly characteristic of
NMO; absence of MS-like plaques in brain and oligoclonal bands in CSF is
also suggestive of this disease. It would be interesting to examine the
patients for stigmata of past attacks of optic neuritis on neuro-ophthalmologic exam and on visual evoked potentials, as well as to test
their NMO IgG status.
We recently reported four patients with MG who underwent
thymectomy and developed clinically definite NMO; two of our four patients
had an elevation in ANA titers. [4]. Concurrently, Furukawa et al,
published two cases of MG followed by NMO: one patient had thymectomy prior
to NMO onset, while the other has been previously diagnosed with SLE [7].
There are presently no less than 13 reports in the literature of
thymectemized myasthenics developing NMO, or recurrent acute myelitis. [4,7,9 and references therein]. In all these cases, MG was diagnosed
prior to the first CNS event. Moreover, in all but one patient with
definite MG and NMO, thymectomy preceded NMO onset.
We agree with the conjecture of Gotkine et al that thymectomy may
lead to breakdown of self-tolerance thereby potentiating development of
autoimmune disease. A systematic analysis of long-term effects of
thymectomy is needed, using non-thymectomized myasthenics as controls, to
assess whether thymectomy indeed confers an increased risk of future
autoimmune disease and what the magnitude of the excess risk is.
It may also be worthwhile to investigate whether thymectomy predisposes to
development of NMO IgG autoantibodies even in the absence of clinical
manifestations of NMO.
References
8. Ghezzi A, Bergamaschi R, Martinelli V, et al. Clinical characteristics, course and prognosis of
relapsing Devic’s Neuromyelitis Optica. J Neurol 2004; 251:47-52.
9. Antoine J-C, Camdessanche J-P, Absi L, Lassabliere F, Feasson L. Devic disease and thymoma with anti-central nervous system and antithymus antibodies
Neurology 2004 62: 978-980.
Disclosure: The authors report no conflicts of interest.
Gotkine et al [1] describe three patients with myasthenia gravis (MG) who underwent thymectomy and subsequently developed either recurrent or monophasic acute myelitis. The authors suggest that these patients may have a "form fruste of SLE", given their elevated ANA titers, though they have not exhibited any non-neurologic manifestations of SLE and had no anti-ds DNA Ab in serum.
Alternatively, we would like to propose that the three patients may have form fruste of Neuromyelitis Optica (NMO). ANA positivity is not an infrequent finding in NMO [8] and would not preclude this diagnosis. All three patients had extensile cord lesions three or more vertebral segments in length, which are highly characteristic of NMO; absence of MS-like plaques in brain and oligoclonal bands in CSF is also suggestive of this disease. It would be interesting to examine the patients for stigmata of past attacks of optic neuritis on neuro-ophthalmologic exam and on visual evoked potentials, as well as to test their NMO IgG status.
We recently reported four patients with MG who underwent thymectomy and developed clinically definite NMO; two of our four patients had an elevation in ANA titers. [4]. Concurrently, Furukawa et al, published two cases of MG followed by NMO: one patient had thymectomy prior to NMO onset, while the other has been previously diagnosed with SLE [7].
There are presently no less than 13 reports in the literature of thymectemized myasthenics developing NMO, or recurrent acute myelitis. [4,7,9 and references therein]. In all these cases, MG was diagnosed prior to the first CNS event. Moreover, in all but one patient with definite MG and NMO, thymectomy preceded NMO onset.
We agree with the conjecture of Gotkine et al that thymectomy may lead to breakdown of self-tolerance thereby potentiating development of autoimmune disease. A systematic analysis of long-term effects of thymectomy is needed, using non-thymectomized myasthenics as controls, to assess whether thymectomy indeed confers an increased risk of future autoimmune disease and what the magnitude of the excess risk is. It may also be worthwhile to investigate whether thymectomy predisposes to development of NMO IgG autoantibodies even in the absence of clinical manifestations of NMO.
References
8. Ghezzi A, Bergamaschi R, Martinelli V, et al. Clinical characteristics, course and prognosis of relapsing Devic’s Neuromyelitis Optica. J Neurol 2004; 251:47-52.
9. Antoine J-C, Camdessanche J-P, Absi L, Lassabliere F, Feasson L. Devic disease and thymoma with anti-central nervous system and antithymus antibodies Neurology 2004 62: 978-980.
Disclosure: The authors report no conflicts of interest.