Peripheral nerve hyperexcitability syndromes / 中华神经科杂志

Peripheral nerve hyperexcitability syndromes (PNHS) encompass a spectrum of a heterogeneous condition with clinical as well as electrophysiological manifestations of peripheral nerve hyperexcitability. The PNHS consist of Isaacs syndrome, Morvan syndrome and Cramp-fasciculation syndrome, which cause widespread symptoms and signs while without evident peripheral nerve disease. Probably the most well-known condition of PNHS is Isaacs syndrome, often called acquired neuromyotonia. Clinical symptoms of PNHS are characterized by muscle twitching, cramps, stiffness, and neuropathic pain. The electrophysiological findings that are very useful in the diagnosis of PNHS are spontaneous myokymic, neuromyotonic, and cramp discharges. An overview of the history, clinical manifestations, pathophysiology, electrophysiological findings and management of PNHS is presented.

Anesthetic experience using total intravenous anesthesia in a patient with Isaacs' syndrome: A case report / 대한마취과학회지

We report on an anesthetic experience with a 74-year-old female with Isaacs' syndrome, who underwent elective surgery for open rotator cuff repair. Isaacs' syndrome is a rare peripheral motor neuron disorder with clinical manifestations such as involuntary muscle twitching, cramps, mild weakness and increased sweating. To avoid prolonged neuromuscular blockade, the patient was observed with neuromuscular monitoring during total intravenous anesthesia with propofol, remifentanil, and atracurium. No adverse events were observed during the anesthetic management, and the patient recovered smoothly from the neuromuscular blockade. We describe the clinical characteristics of Isaacs' syndrome and its specific considerations in anesthesia.

Isaacs' Syndrome Associated With Acetylcholine Receptor Antibodies Developed After Removal of Malignant Thymoma

Isaacs' syndrome is a rare and heterogeneous syndrome of continuous muscle fiber activity that originates from peripheral nerves. We report a 56-year-old male patient who showed symptoms of Isaacs' syndrome after the removal of a malignant thymoma. Needle electromyography revealed spontaneously occurring repetitive myokymic discharge in the affected muscles. Acetylcholine receptor (AChR) antibodies were significantly elevated, but clinical and electrophysiologic findings did not indicate the presence of myasthenia gravis. We deduce that in Isaacs' syndrome, raised AChR antibodies may facilitate rather than inhibit cholinergic action.

Isaacs syndrome:a case report / 中国康复理论与实践

@#ObjectiveTo analyze the clinical features and pathogenesis mechanism of Isaacs syndrome.MethodsA case with Isaacs syndrome was reporttedResults and ConclusionIsaacs syndrome is characterized by the occurrence of spontaneous and continuous muscle fiber activity, associated with muscle cramps, pseudomyotonia and myokymia, stiffness and delayed relaxation of the muscle. The stiffness and myokymia are present at rest and during sleep. Isaacs syndrome has been recently suggested to be produced through an immune-mediated mechanism in which voltage-gated potassium channels may be targeted by auto-antibodies.

A Case of Isaacs' Syndrome Associated with Small Cell Lung Cancer

Isaacs' syndrome consists of spontaneously occurring muscle activity of peripheral nerve origins. This syndrome arises in association with/without polyneuropathy and rarely with malignancy. A 63-year-old man was admitted to our hospital due to generalized painful muscle stiffness. He complained of difficulty with standing and with finger exten-sion after grasping. Chvostek's and Trousseau's signs were noticed. Electrolytes, calcium, CK, and LDH were in the normal range. Small cell lung cancer was diagnosed by a needle biopsy. Electrophysiological testing revealed normal nerve conduction studies with the exception of a grossly abnormal EMG. Continuous neuromyotonic discharges with firing rates of 120-200 Hz were seen at rest. The amplitude of the response typically waned with 0.5-1.5 seconds of duration. The discharges persisted throughout sleep, after diazepam injection, and with brachial plexus blockage.Muscle stiffness improved with the administration of oral phenytoin. Under chemotherapy and radiotherapy, tumor remission was partially achieved and neurological symptoms markedly improved.