Neurology & Pain Management Coding Alert

Myasthenia gravis is an autoimmune disease in which the body produces autoantibodies that block the muscle cells from receiving impulses/signals from the nerve cells and hence interfere with neuromuscular conduction. These antibodies can block, inhibit, or destroy the acetylcholine receptors to block neuromuscular conduction. This produces muscle weakness of the voluntary muscles which worsens during activity and improves with rest.

Cholinesterase inhibitors like edrophonium (called Tensilon or Enlon) when given to patients with myasthenia will reduce the muscle weakness. These prolong the presence of acetylcholine around the nicotinic receptors in the neuromuscular cleft and facilitate conduction.

Using a cholinesterase inhibitor, your physician will make an attempt to distinguish between myasthenia gravis, cholinergic crisis, and Lambert-Eaton myasthenic syndrome. The muscle weakness is worsened in cholinergic crisis and there is no decrease observed in muscle strength in the Lambert-Eaton syndrome.

Dx codes: You report ICD-9 code 358.00 (Myasthenia gravis without [acute] exacerbation) for myasthenia gravis. For an acute exacerbation or crisis, you report code 358.01 (Myasthenia gravis with [acute] exacerbation). Myasthenic crisis is a condition characterized by weakening of the muscles of breathing such that the patient needs ventilatory support. Myasthenic crisis is a medical emergency that can be triggered by infection, fever, or an adverse reaction to medication.