Morvan's fibrillary chorea: a paraneoplastic manifestation of thymoma

Abstract

Morvan's fibrillary chorea is a rare disease characterised by symptoms which include neuromyotonia, cramping, weakness, pruritis, hyperhidrosis, insomnia, and delirium. The first case of Morvan's fibrillary chorea to be associated with clinical manifestations of myasthenia gravis with thymoma, psoriasis, and atopic dermatitis is reported. Muscle histopathology disclosed chronic denervation and myopathic changes and in vitro electrophysiology demonstrated both presynaptic and postsynaptic defects in neuromuscular transmission. Serum antibodies to acetylcholine receptors, titin, N-type calcium channels, and voltage gated potassium channels were detected. Plasmapheresis, thymectomy, and long term immunosuppression induced a dramatic resolution of symptoms. The association of thymoma with other autoimmune disorders and autoantibodies, and prolonged and sustained remission with chronic immunosuppression, place Morvan's fibrillary chorea on the range of neurological diseases arising as a paraneoplastic complication of cortical thymomas. (J Neurol Neurosurg Psychiatry 1998;65:857-862) Keywords: Morvan's fibrillary chorea; neuromyotonia; thymoma; paraneoplastic La chorée fibrillaire was first coined by Morvan in 1890 when describing patients with multiple, irregular contractions of the long muscles, cramping, weakness, pruritis, hyperhidrosis, insomnia, and delirium.1 Additional cases of Morvan's fibrillary chorea have been reported, but only four cases are in the English literature, perhaps as a matter of semantics.2 3 Neuromyotonia and Isaacs' syndrome (continuous muscle fibre activity) are used interchangeably to refer to muscle twitching and cramping at rest, that is exacerbated with exercise. 4 It is caused by sustained or repetitive spontaneous muscle activity of peripheral nerve origin. Electromyography discloses spontaneous, repetitive motor unit or single fibre discharges firing in irregular rhythmic bursts at high intraburst frequencies. Myokymia, or spontaneous rippling and twitching movements of muscles, is a visible component of neuromyotonia and Isaacs' syndrome. 5 Morvan's fibrillary chorea is a syndrome that is characterised by not only neuromyotonia, but also dysautonomia and CNS dysfunction, often in the form of encephalopathy.The association of the disease with thymoma, tumour, autoimmune diseases, and autoantibodies suggests an autoimmune or paraneoplastic aetiology. Thymoma, prostate adenoma, and in situ carcinoma of the sigmoid colon, have been found in patients with Morvan's fibrillary chorea.2 3 In other patients, heavy metal intoxication with gold, mercury, and manganese, known stimulants of the immune system, has been implicated as a cause. [6][7][8] Anti-acetylcholine receptor (antiAChR) antibodies have been detected in patients with thymoma, but without clinical manifestations of myasthenia gravis.2 Raised CSF IgG concentrations and oligoclonal bands have been reported in patients with psychosis.3 9In addition, some of the individual components of Morvan's fibrillary chorea are sus...

Myokymia and neonatal epilepsy caused by a mutation in the voltage sensor of the KCNQ2 K + channel

“…A similar suppression of voltage-gated K ϩ currents was observed with serum from a patient with Guillain-Barré syndrome, a disease often showing transient myokymic discharges during early stages (8,9). Antibodies to voltage-gated K ϩ channels are also detected in patients with Morvan's fibrillary chorea (3).…”

“…Localized myokymic activity can have its cause in circumscribed disturbances of peripheral nerves or the central nervous system, e.g., in snake poisoning, hypoxia, radiation therapy, pontine tumors, or multiple sclerosis. Generalized myokymia, with or without associated muscle stiffness and delayed relaxation is a feature of Isaacs' syndrome (including acquired neuromyotonia) (1), episodic ataxia type 1 (2), and Morvan's fibrillary chorea (3). In some patients the spontaneous muscle movement occurs without apparent underlying cause, and the frequently positive family history (Ϸ30%) indicates that genetic factors are among the possible causes of idiopathic generalized myokymia (IGM) (4).…”

Fasciculations, Autonomic Symptoms and Limbic Encephalitis: A Thymoma-Associated Morvan’s-Like Syndrome

“…Although these antibodies have usually been found to be present, whenever tested, in more recent publications of Morvan's syndrome [1,3,6,7] , they were found to be absent in many patients with this diagnosis [12 ; A. Vincent, unpubl. observations].…”

“…With only a limited number of reported cases, the complete spectrum of the CNS symptomatology in Morvan's syndrome has not been well established. These symptoms have been noted to bear a striking similarity to limbic encephalitis (LE) [1][2][3] ; however, there has not been convincing evidence of LE with demonstrable involvement of limbic structures associated with a PNH syndrome except for 2 cases [2,4] .We present a patient with thymoma and myasthenia gravis who had an episode with fasciculations, autonomic symptoms and memory impairment while in pharmacological remission 9 years after the removal of the thymoma. LE was well defi ned both by neuropsychological tests and magnetic resonance imaging (MRI) studies.…”

Dreaming: a neurological view

“…Limbic encephalitis This is a rare disorder which has been linked with autoantibodies against voltage-gated potassium channels and with the presence of REM sleep behaviour disorder [130,131].…”