Biomedical subjects

Jonathan S. Katz

Publications and source records attributed to Jonathan S. Katz.

4 recordsLinked to original sources

PubMed2004

Inflammatory Myopathies.

Therapies that suppress or modify the immune system remain the primary treatment for the idiopathic inflammatory myopathies. Dermatomyositis (DM) and polymyositis (PM) are the two conditions that respond best to immunotherapy. Although there are no randomized controlled trials, corticosteroids, specifically high-dose oral prednisone, remain the cornerstone of management. Recent controlled clinical trials show that intravenous immunoglobulin (IVIg) is an efficacious treatment in DM. Expert clinicians are generally using this as a second-line agent or as an adjunct to prednisone. IVIg has a relatively benign side effect profile compared with chronic steroid use, but the cost of treatment, the need for repetitive treatment cycles, and the potential for serious adverse effects have kept it from being a first-line agent in DM. There have been no trials performed using IVIg in PM. Chronic immunosuppressant medications, including azathioprine, cyclosporine, and methotrexate, are also available for long-term management in patients with recalcitrant disease or side effects from extended corticosteroid use. These agents lack the troubling side effects of prednisone and are less costly than IVIg, but require close medical monitoring for adverse reactions to blood, kidney, lung, or liver. Newer medications with potentially more benign side effect profiles, such as mycophenolate mofetil and etanercept, are currently being studied, but knowledge of how effective they are and how quickly they work are not yet available. Inclusion body myositis has proven resistant to immunosuppressive medications. The response has been so consistently poor and so easily contrasted with DM that the authors wonder why these conditions are so routinely lumped together in chapters and review articles. Clearly, this is based solely on the common pathologic feature of inflammation, rather than a clear understanding of how these conditions occur, or why they do or do not respond to treatment.

Journal Article↗

PubMed2004

Myasthenia Gravis.

Myasthenia gravis is a disorder of neuromuscular transmission, manifest by variable weakness of skeletal muscle. The disorder has a range of therapies that differ with respect to efficacy, timing, and side effects. The physician treating myasthenia gravis must be well versed in understanding the evidence basis for using these agents, as well as the trade-offs between persistent disease manifestations and their costs and expected benefits. Diagnosis of myasthenia gravis depends on recognizing the pattern of weakness, which typically involves some combination of extraocular, bulbar, facial, limb, and neck muscles. Management relies on some combination of medications that influence the function of the neuromuscular junction and treatments that alter the immune response. Thymectomy is commonly used, although trends in evidence-based medicine are leading expert clinicians to look closely at its efficacy. Plasma exchange is useful for patients in crisis, who require rapid improvement. The exact role for high-dose intravenous immunoglobulin in this setting is still being studied, although the agent is gaining popularity. Knowing that the treatments are effective is not enough. It is still important to determine the treatment that has a more rapid onset, because these patients often require intensive care or respiratory assistance.

Journal Article↗

PubMed2003

Chronic Inflammatory Demyelinating Polyneuropathy.

Although there are close to 10 randomized trials showing efficacy for prednisone, intravenous immunoglobulin, or plasmapheresis in chronic inflammatory demyelinating polyneuropathy (CIDP), large differences in cost, side effect profiles, and ease of use create controversy over the therapy that is best. Most clinicians use intravenous immunoglobulin or prednisone as first-line therapy. Unfortunately, the clinical trials performed to date are not easily extrapolated to answer, "which agent is best for clinical practice" because they have used varying doses and duration of therapy, different diagnostic criteria for CIDP, and mixtures of patients who have failed previous therapy versus those with newly diagnosed disease. There are a number of small case series describing the efficacy of immune-modulating agents, such as azathioprine, cyclophosphamide, cyclosporine A, interferon-alpha, and mycophenolate mofetil. These studies generally use these medications as second-line agents for patients who failed corticosteroids or intravenous immunoglobulin. In the authors' practice, this lack of robust knowledge still relegates these to second-line or prednisone-sparing agents.

Journal Article↗

PubMed2001

Asymmetric Acquired Demyelinating Polyneuropathies: MMN and MADSAM.

More than a half a century after Austin's initial description of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), the clinical spectrum of chronic acquired demyelinating polyneuropathies has expanded. Currently there are a number of entities that can be put under the heading of chronic acquired demyelinating neuropathy (CADP) based on differing clinical presentations. In this scheme, CIDP is used only to refer to patients with demyelinating neuropathies and generalized symmetric weakness. In contrast, multifocal motor neuropathy (MMN) and multifocal acquired demyelinating sensory and motor neuropathy (MADSAM) fall into the category of asymmetrical, multifocal forms of CADP. These are distinguished from each other only by the presence of sensory involvement. In our opinion, there are pragmatic reasons for splitting these clinical presentations into distinct entities. Although each of these clinical subtypes shares some basic similarities, there are important differences. MMN is usually considered resistant to corticosteroid therapy and the first line agent in this disorder is intravenous immunoglobulin (IVIg). MADSAM neuropathy can be responsive to prednisone or IVIg, and has a profile more analogous to classic CIDP with regards to its laboratory features and treatment response.

Journal Article↗