(Kiosk 3) Severe Calf Pain, Spasm, and Hypertrophy in the Setting of Remote Lumbar S1 Radiculopathy – Neurogenic Hypertrophy a Focal Form of Neuromyotonia?

Case Diagnosis: 62-year-old female with painful calf cramping and hypertrophy following remote lumbosacral radiculopathy representative of neurogenic hypertrophy versus neuromyotonia.

Case Description or Program Description: A 62-year-old female presented with a five-month history of severe pain from left calf cramping with episodes of sustained muscle contraction for approximately 5-10 minutes, 2-3 times a week. The spasms were unpredictable, often in the evening at rest. They were not relieved with stretching and the severity has caused vasovagal syncope. She had a history of MRI-confirmed L5-S1 left lateral disc herniation and nerve impingement approximately 6 years earlier which resolved with conservative treatment. At presentation, the patient had no motor or sensory deficits, left greater than right calf hypertrophy (circumference: 2cm larger at the distal calf and 1cm larger at the proximal calf). The electrodiagnostic study showed mildly decreased recruitment and/or large amplitude motor units of the left medial gastrocnemius, left peroneus longus, left posterior tibialis muscles consistent with chronic denervation/partial reinnervation in the left L5-S1 distribution. Repeat MRI was consistent with lower lumbar degenerative changes with moderate left L5-S1 lateral recess and foraminal stenosis.

Setting: Tertiary academic health center

Assessment/Results: This patient had severe left calf cramping and hypertrophy with remote left S1 radiculopathy most consistent with neurogenic hypertrophy. She had residual nocturnal continuously contracting/twitching muscles suggestive of a neuromyotonia.

Discussion (relevance): This is a unique presentation of calf spasms and hypertrophy in the setting of prior nerve root compression. A presentation of asymmetric hypertrophy secondary to nerve injury has been documented in the literature as neurogenic hypertrophy. Neuromyotonia is a spontaneous peripheral nerve discharge with an autoimmune etiology. This case suggests that neurogenic hypertrophy may exist on the same spectrum of disease as neuromyotonia secondary to mechanical injury.

Conclusions: Neurogenic hypertrophy is a rare and remote sequela of lumbosacral radiculopathies, and may be a mechanical, as opposed to autoimmune, etiology for focal neuromyotonia.