Angia Chen, BS (she/her/hers)
Medical Student
Morehouse School of Medicine
Duluth, Georgia, United States
Charlie D. Brennan, BA
Medical Student
University of Missouri
Columbia, Missouri, United States
W. David Arnold, MD
Executive Director of NextGen Precision Health
University of Missouri-Columbia, Department of Physical Medicine & Rehabilitation
Columbia, Missouri, United States
Jaime D. Basnett, MSN
ALS Research Program Manager, APRN-BC, CCD.
NextGen Precision Health
Columbia, Missouri, United States
Cramp-fasciculation syndrome (CFS)
Case Description: A 76-year-old man with a 10-year history of severe, episodic muscle stiffness lasting 15-20 minutes per episode was referred for evaluation of possible stiff person syndrome. He had been treated with diazepam and baclofen, which provided 80% relief but caused sedation. Examination showed occasional fasciculations but was otherwise normal. Anti-GAD antibody testing was negative. Electrodiagnostic studies revealed normal motor and sensory responses, with fasciculations on needle EMG. Repetitive nerve stimulation of the tibial nerve showed increased after-discharges at 10 Hz, suggesting peripheral nerve hyperexcitability. He was diagnosed with CFS and prescribed ranolazine 1000 mg twice daily, leading to complete resolution of symptoms. Over 1.5 years of follow-up, symptoms only recurred when he temporarily stopped ranolazine but resolved upon restarting.
Discussions:
CFS is a peripheral nerve disorder marked by motor nerve hyperexcitability, causing muscle cramps and fasciculations. While CFS shares features with other hyperexcitability syndromes like neuromyotonia, CFS lacks continuous muscle contractions. Common treatments include anticonvulsants like carbamazepine, which can cause intolerable side effects. The successful use of ranolazine, a late sodium current blocker indicated for chronic angina, is notable since it is not a common treatment for CFS. Ranolazine has been shown to reduce cramp frequency in patients with ALS. The complete resolution of this patient’s symptoms suggests that ranolazine may be a valuable alternative for managing CFS, particularly for those who experience side effects from standard treatments.
Conclusions:
Ranolazine completely resolved severe muscle cramps in this case of CFS, offering a promising new therapeutic option. Its success highlights the potential for ranolazine to be an effective alternative, especially for patients that are intolerant to standard therapies. Further research into its broader use in CFS and other peripheral nerve hyperexcitability disorders could significantly expand treatment options for these challenging conditions.
