CNS auto-inflammatory diseases can cover a wide spectrum, and it is often important to distinguish between CNS vasculitis, neurological manifestations of connective tissue disease such as SLE, and other mimickers. A workshop entitled "CNS Immune Inflammatory Disorders" addressed this issue. The speakers focused on three different diagnoses that can mimic CNS vasculitis that should be considered in the workup and diagnosis of patients with neurological symptoms.
One major consideration is Multiple Sclerosis (MS). MS is the leading cause of acquired neurological disability in young adults. It is more common in women, with a ratio of 3:1 females to males. All diagnostic criteria for MS are based on two main principles: i) CNS lesions must be disseminated in space and time, and ii) all other potential explanations for the symptoms should be ruled out. The McDonald criteria have undergone several revisions, the most recent being in 2011. Perhaps the most significant change in the latest revision is the inclusion of MRI criteria in the diagnosis of MS, and one can now make a diagnosis of MS at first presentation with a single MRI. However, these criteria still don't enable one to differentiate between other conditions that can also present with dissemination of findings in space and time.
There are four typical manifestations of MS. These include optic neuritis (ON, often unilateral with pain on eye movement); brainstem presentations (e.g. internuclear ophthalmoplegia, cranial nerve 6 palsies, facial nerve palsies); spinal cord syndrome (partial transverse myelitis); and cerebral syndrome (subcortical cognitive dysfunction, usually affecting information processing as well as short-term memory). Findings unusual for MS include severe cases of ON with unresolving symptoms, cranial nerve 3 palsies, severe neurological findings including complete loss of all function below a certain neurological level, as well as hemianopsia and seizures, although seizures can occur.
Another diagnosis to consider is Neuromyelitis Optica Spectrum Disorder (NMOSD), also known as Devic's disease. This is a relapsing demyelinating inflammatory disease that targets optic nerves and the spinal cord. Patients may present with sudden loss of vision, weakness in one eye or both, as well as loss of sensation and bladder function. This disorder is also seen more often in females, with a median age at diagnosis of 40 years. Typical findings of this disorder include the presence of oligoclonal bads in 20% of cases and patients being negative for HLA-DR 2. Ten percent of patients can have a monophasic course, and over 20% of cases of demyelinating diseases are seen in East Asian patients, with less than 1% of cases seen in European caucasians. Up to 50% of patients may have elevated autoantibodies or other autoimmune diseases, including Sjogren's syndrome or SLE. However, these autoimmune diseases are NOT considered a manifestation of NMOSD, rather an independent diagnosis. NMOSD can also be seen with other neurological disorders such as Myesthenia Gravis. Diagnostic criteria includes several neurological manifestations other than typical findings of ON and transverse myelitis, including narcolepsy, unexplained hiccups, nausea and vomiting, among others. NMO IgG is a serum marker for NMOSD, and has a sensitivity of 73% and specificity of 91% for distinguishing NMOSD from MS. The NMO IgG is directed against the most common water channel in the CNS, known as aquaporin-4. It is significant because seropositive patients may have a higher rate of relapse.
Finally, neurosarcoidosis can target any part of the nervous system, but commonly targets cranial nerves (especially CN 7), and can also cause aseptic meningitis. Neurosarcoidosis is seen in 5-10% of patients with sarcoidosis and may be the presenting symptom in 50-70% of patients. In 10-17% of patients, neurosarcoidosis may be the only presenting symptom of sarcoidoisis without any other systemic manifestations. Facial nerve palsy is the most common finding, and can be unilateral or bilateral, and is often self-limited. Meningitis can cause headaches, hydrocephalus, and cranial nerve palsies. Myelopathies can also occur, often at the cervical and thoracic levels, resulting in difficulty walking, leg weakness and vague and diffuse sensory symptoms. Other manifestations include stroke, CNS vasculitis and cerebral sinus thrombosis. Peripheral nerves, both large and small fibres, can also be targetted. Neurosarcoidosis can result in cognitive dysfunction, usually due to meningitis or effects of an intracranial mass lesion.