Inherited Myokymia: A Clinical and Genetic Study of a Family

Neuromyotonia (NMT), so called Isaac's syndrome, is a rare disorder in which hyperexcitability of peripheral motor nerves leads to intermittent muscle contractions. It is characterized by muscle twitching at rest (visible myokymia), cramps, hyperhidrosis, paraesthesiae, mild muscle weakness. and impaired muscle relaxation, or pseudomyotonia. Electromyographic recording is a key diagnostic tool in detecting myokymia and neuromyotonia. Pathophysiology of neuromyotonia is claimed to be related immune disorder, autoimmune anti-voltage-gated potassium-channel antibodies and genetic mutation in potassium channel. KCNA1 (Kv1.1) mutation was mostly reported in a autosomal dominant trait. In the present study, we report a family affected with myokymia，worsening with elevated body temperature, febrile illness or spicy food. How the change in temperature influence clinical features of channelopathies is an interesting topic. Variant clinical severity of family members are recorded. The index patient has possible autoimmune mechanism involvement because of his clinical feature of myasthenia gravis with thymoma and hyperthyroidism. Further analyzing the genetic mutation in potassium channelopathy may provide researchers some pathophysiological insight into the Isaac's syndrome.

Study Overview

• Status: Unknown
• Conditions: A Study of Clinical and Genetic Mutations in a Family of Neuromyotonia, so Called Isaac's Syndrome

• Study Type: Observational
• Enrollment (Anticipated): 18

Contacts and Locations

Study Locations

• Taiwan
  • Taichung, Taiwan, 404
    • Recruiting
    • China Medical University Hospital
    • Contact: Yi-ting Hsu, MD; Phone Number: 5039 886-4-22062121; Email: formosa1005@yahoo.com.tw
  • Taichung, Taiwan, 404
    • Not yet recruiting
    • China Medical University Hospital
    • Contact: Chon-Haw Tsai, MD, PhD; Phone Number: 5030 886-4-22062121; Email: windymovement@yahoo.com.tw
    • Principal Investigator: Yi-Ting Hsu, MD
    • Principal Investigator: Chon-Haw Tsai, MD,PhD
    • Principal Investigator: Yu-Wan Yang, MD,MS
    • Principal Investigator: FUU-JEN Tsai, MD, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

We interview and examine the family members directly at our hospital and home visit or indirectly by telephone visit.

Description

Inclusion Criteria:

• The disease was initially diagnosed of Isaacs syndrome by two neurologist(Dr Tsai and Dr Yang). We will recruit family members of diseased patient and normal subjects for clinical, electromyographic and genetic studies.

Exclusion Criteria:

• none

Study Plan

How is the study designed?

Design Details

• Observational Models: Case-Only
• Time Perspectives: Cross-Sectional

Collaborators and Investigators

• Sponsor: China Medical University Hospital
• Investigators: Study Director: Yi-Ting Hsu, MD, China Medical University Hospital

Study record dates

Study Major Dates

• Study Start: April 1, 2010
• Primary Completion (Anticipated): March 1, 2011

Study Registration Dates

• First Submitted: November 29, 2010
• First Submitted That Met QC Criteria: November 29, 2010
• First Posted (Estimate): December 1, 2010

Study Record Updates

• Last Update Posted (Estimate): December 1, 2010
• Last Update Submitted That Met QC Criteria: November 29, 2010
• Last Verified: November 1, 2010

More Information

Terms related to this study

• Keywords: Neuromyotonia, Isaac's syndrome; Peripheral nerve hyperexcitability; Myokymia; Potassium channelopathy
• Additional Relevant MeSH Terms: Nervous System Diseases; Neurologic Manifestations; Musculoskeletal Diseases; Muscular Diseases; Neuromuscular Diseases; Peripheral Nervous System Diseases; Neuromuscular Manifestations; Isaacs Syndrome; Myokymia
• Other Study ID Numbers: DMR99-IRB-190