Lupus Eye Research Unit, Institute of Ophthalmology and
1 Third School of Internal Medicine, La Sapienza University, Rome, Italy
We read the letter by Hutchinson et al. with great interest. In fact, a hypothesis considering Devic's neuromyelitis optica as a primary autoimmune disease is most suggestive. Nevertheless, in our opinion some considerations should be made regarding this controversial disease.
Since the first description by Eugène Devic (1894), of patients with neuromyelitis optica, the concurrence of transverse myelopathy with optic neuropathy, both as isolated and in association with various systemic diseases, has been repeatedly reported by several authors [14]. Although ample time has been dedicated to this subject by numerous research groups, at present both its aetiology and its pathogenesis still remain to be fully clarified.
In our opinion, when a neuromyelitis optica occurs in association with a systemic disease, such as multiple sclerosis (MS), systemic lupus erythematosus (SLE) or anti-phospholipid syndrome (APS), it is not simple to establish whether its occurrence in these patients may be classified as a secondary Devic-like disorder or as a strict Devic's syndrome.
Interestingly, to this regard, Mandler et al. [4] proposed a set of diagnostic criteria potentially useful to distinguish strict Devic's neuromyelitis optica (Devic's syndrome) from the neuromyelitis optica that may occur in the course of MS (Devic-like disorder).
In particular, Mandler's criteria emphasize as follows:
1. Clinical: Acute involvement of spinal cord and optic nerves, either coincidental or separated by months or years, independent of its subsequent progression, but without the development of brainstem, cerebellar, or cortical features at any time in the disease course.
2. Imaging: Normal-appearing brain MRI; enlargement and cavitation on spinal cord MRI.
3. Cerebrospinal fluid: Decreased serum/CSF albumin ratio with normal CNS daily IgG synthesis and usually an absence of oligoclonal bands.
4. Pathology: Spinal cord necrosis and cavitation with thickened vessel walls and absence of inflammatory infiltrates; demyelination of optic nerves with or without cavitation; no demyelinating lesions in the brain, brainstem, or cerebellum.
If we consider the exactness of these diagnostic criteria, we have several patients with some systemic diseases, such as MS, SLE and APS, who cannot be classified as suffering from a strict Devic's syndrome, but, only as affected by a Devic-like disorder. In fact, it is possible that in the course of MS, SLE and APS, neuromyelitis optica occurs in association with cortical or cerebellar features or with an abnormal-appearing brain MRI; therefore, these patients do not satisfy the criteria proposed by Mandler et al. [4] In our opinion, in order to give a better distinction between a strict Devic's syndrome and a Devic-like disorder that may occur in the course of SLE or APS, it could be useful for clinicians to add another two criteria to those proposed by Mandler et al. [4]: the absence of the 1982 American Rheumatism Association (ARA) criteria for the diagnosis of SLE; and the absence of an APS.
What we would like to know is whether the pathophysiology of isolated neuromyelitis optica is different or similar to the pathophysiology of neuromyelitis optica which occurs in the course of MS, SLE or APS.
In conclusion, on one hand we have patients with neuromyelitis optica who satisfy Mandler's criteria and are not suffering from those abnormalities which indicate the presence of a systemic disease. In particular, we believe that they can be considered as having a primary Devic's syndrome. On the other, we have a group of patients with various clinical and laboratory features, which can probably be classified as suffering from a secondary Devic's syndrome; in particular, this latter group of patients should include those affected by MS, APS, SLE, including those with less than four 1982 ARA criteria for a lupus diagnosis (lupus-like disease).
Additionally we would like to know whether a common pathogenetic factor able to induce the occurrence of neuromyelitis optica in the course of both primary and secondary Devic's syndrome exists (Fig. 1).
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Finally, in their interesting letter, Hutchinson et al. proposed that isolated Devic's neuromyelitis optica is an autoimmune disease in its own right, but unfortunately both its aetiology and its pathogenesis still remain to be fully clarified.
Notes
3 Correspondence to: D. Giorgi Via Guglielmo degli Ubertini 64, 00176 Rome, Italy.
References