|Year : 2016 | Volume
| Issue : 1 | Page : 55-57
An unusual cause of recurrent falls
Piyush Ostwal1, Varsha S Dabadghao2, Suresh K Sharma2, Anurag Aggarwal2
1 Department of Neurology, Dr. D. Y. Patil Medical College, Hospital and Research Centre, Pune, Maharashtra, India
2 Department of Medicine, Dr. D. Y. Patil Medical College, Hospital and Research Centre, Pune, Maharashtra, India
|Date of Web Publication||5-Feb-2016|
601, N4, Nakshatram, Premlok Park, Chinchwad, Pune - 411 033, Maharashtra
Source of Support: None, Conflict of Interest: None
Patient with recurrent falls presenting to the physician poses a diagnostic and therapeutic challenge. Detailed clinical and laboratory evaluation often results in precise diagnosis. We present here a case who presented with recurrent falls and was diagnosed to have myotonia congenita (MC) of Becker's type. He had typical clinical signs of myotonia such as grip myotonia and percussion myotonia. Myotonic disorders should be considered in patients presenting with recurrent falls and clinical testing for myotonia should be done. Electromyography and muscle histopathology are important adjuncts to the diagnosis of MC.
Keywords: Myotonia congenita, myotonic discharges, recurrent falls
|How to cite this article:|
Ostwal P, Dabadghao VS, Sharma SK, Aggarwal A. An unusual cause of recurrent falls. J Med Soc 2016;30:55-7
| Introduction|| |
A fall is an event which results in a person coming to rest inadvertently on the ground, or floor, or other lower level.  An individual presenting with recurrent falls needs evaluation for a variety of neurological, cardiac, and orthopedic etiologies. The process of diagnosis begins with a history and clinical examination which can guide us to the final etiology. Here, we report a patient who presented to us with the history of recurrent falls which was eventually diagnosed as myotonia congenita (MC).
| Case Report|| |
A 20-year-old male, college student, had a history of recurrent falls since 10 years of age. He reported an inability to relax or fold his limbs and "getting stuck" after prolonged rest.
He also had difficulty in getting up from squatting position and stiffness in muscles. All these symptoms were slowly progressive in nature. He reported no weakness of upper limbs or distal lower limbs. He had no history suggestive of higher mental function, cranial nerve, or sensory involvement. He was born of a nonconsanguineous marriage and no family member had similar complaints.
His vitals were normal. The musculature showed generalized hypertrophy (Herculean appearance) in both upper and lower limbs.
The higher mental functions and cranial nerve examination were normal. Wasting was noted in both hands distally. Power at all joints in both upper and lower limbs was Medical Research Council Grade 5 (normal). Grip myotonia and percussion myotonia were elicitable over the tongue and limb muscles [Figure 1]. Tendon reflexes were normal, and plantars were flexor.
|Figure 1: Comparative photograph showing percussion myotonia in the form of dimpling of the calf muscle (a) On striking with a knee hammer which slowly fills up over next few seconds (b)|
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Complete blood count with smear examination, liver function tests, renal function tests, serum proteins, and urine routine microscopy were within normal limits. His serum potassium and sodium was normal. Creatine kinase level was also normal. Serum calcium level was 9.2 mg/dL, which was within normal range. Chest X-ray, ultrasonography of abdomen, and echocardiography were normal. Needle electromyography revealed classic waxing and waning myotonic discharges [Figure 2].
|Figure 2: Needle electromyographic recording of myotonic discharges from resting muscle showing typical waxing and waning of amplitude and frequency. Furthermore, the discharges were associated with "revving engine" sound on speaker|
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Muscle histopathology was essentially normal [Figure 3].
|Figure 3: Photomicrograph of muscle biopsy showing normal preserved architecture of the muscle fibers|
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The evidence of myotonia suspected on history and elicited on examination helped us in clinching the diagnosis in this case. The myotonic discharges were subsequently also confirmed on electromyography. The normal preserved histology on muscle biopsy ruled out the diagnosis of myotonic dystrophy. Based on the age of onset in the second decade, our patient was finally diagnosed to have MC of Becker's type. The patient was started on phenytoin (200 mg/day) and physiotherapy for symptomatic treatment of myotonia.
| Discussion|| |
Recurrent falls and other motor difficulties are the most important symptoms which bring patients with muscle disease to medical attention. A systematic history and physical examination help immensely in narrowing down the diagnosis in muscle diseases.
Myotonia refers to the tonic spasm of muscle after forceful voluntary contraction.  It is the clinical expression of underlying muscle hyperexcitability.
MC includes two variants - autosomal dominant Thomsen's disease and autosomal recessive Becker's disease. The worldwide prevalence of MC is estimated at 1/100,000.  Becker's disease is more common than Thomsen's disease. MC is a disorder of muscle chloride channels, the gene for which resides on chromosome 7q35.  With impeded chloride conductance of muscle membrane, the increase in potassium concentration in the transverse tubules can no longer be negated effectively and hence lead to repetitive electrical discharge of the membrane, producing electrical and clinical myotonia. 
The onset of symptoms is usually in infancy or early childhood in Thomsen's disease, whereas it is after 10 years of age in Becker's disease. The muscle stiffness characteristically alleviates after repeated contractions (warm up effect). The reverse is seen in paramyotonia congenita where myotonia worsens with repeated contractions. On tapping a muscle belly with a hammer, sustained contraction can be elicited which is known as "percussion myotonia." Similarly, inability to quickly release a tightly clenched fist is referred to as "grip myotonia." The myotonic stiffness after prolonged sitting is a common cause of falls in such patients on getting up and on taking the first few steps while walking. Muscle hypertrophy, due to almost continuous muscle contraction, is more often present in Becker's disease and lead to the classic description of such patients as "Herculean appearance." The effect of cold on myotonia in MC is not as pronounced as in paramyotonia congenita. Mild or no weakness is seen in MC distinguishing it from myotonic dystrophy which is a relentlessly progressive myopathy. Furthermore, the presence of systemic findings of cataract, cardiac abnormalities, frontal balding, skeletal deformities, and glucose intolerance in a patient with myotonia are pointers for myotonic dystrophy. Creatine kinase may be moderately elevated in Becker's type of MC.
Electromyography shows characteristic "waxing and waning" pattern of myotonic discharges. Muscle biopsy shows normal muscle fibers differentiating it from myotonic dystrophy, and other muscle diseases with rare myotonic discharges such as acid maltase deficiency, polymyositis, and myotubular myopathy.  The genetic testing for over 50 point mutations in muscle chloride channel gene is possible, but it is not widely available. 
| Conclusion|| |
MC should be considered in young patients presenting with the history of recurrent falls. It may be misdiagnosed in initial stages as a muscular dystrophy. Once suspected, the clinical signs of myotonia are unmistakable. With advances in genetics and pharmacology, more effective treatment options are expected in future.
We are thankful to Dr. Harshwardhan, Professor in Pathology, Dr. D. Y. Patil Medical College, Hospital and Research Centre for the histopathology support.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]