Denervation pseudohypertrophy of calf muscles associated with diabetic neuropathy

Muscle hypertrophy following acquired neurogenic injury: systematic review and analysis of existing literature

OBJECTIVES

Neurogenic muscle hypertrophy (NMH) is a rare condition characterized by focal muscle hypertrophy caused by chronic partial nervous injury. Given its infrequency, underlying mechanisms remain poorly understood. Inspired by two clinical cases, we conducted a systematic review to gain insights into the different aspects of NMH.

METHODS

We systematically searched online databases up until May 30, 2023, for reports of muscle hypertrophy attributed to acquired neurogenic factors. We conducted an exploratory analysis to identify commonly associated features. We also report two representative clinical cases.

RESULTS

Our search identified 63 reports, describing 93 NMH cases, to which we added our two cases. NMH predominantly affects patients with compressive radiculopathy (68.4%), negligible muscular weakness (93.3%), and a chronic increase in muscle bulk. A striking finding in most neurophysiological studies (60.0%) is profuse spontaneous discharges, often hindering the analysis of voluntary traces. Some patients exhibited features consistent with more significant muscle damage, including higher creatine phosphokinase levels, muscle pain, and inflammatory muscle infiltration. These patients are sometimes referred to in literature as "focal myositis." Treatment encompassed corticosteroid, Botulinum Toxin A, decompressive surgery, antiepileptic medications, and nerve blocks, demonstrating varying degrees of efficacy. Botulinum Toxin A yielded the most favorable response in terms of reducing spontaneous discharges.

INTERPRETATION

This systematic review aims to provide a clear description and categorization of this uncommon presentation of an often-overlooked neurological disorder. Though questions remain about the underlying mechanism, evidence suggests that aberrant fiber overstimulation along with increased workload that promotes focal damage may result in muscle hypertrophy. This may serve as a guide for therapeutic interventions.

Denervation pseudo hypertrophy of the calf: An important cause of lower limb swelling

Denervation pseudohypertrophy is an uncommon cause of limb swelling, which may be overlooked. It is an important diagnosis to arrive at, as it instructs the search for an underlying cause which may itself require intervention. We present the case of a 32-year-old male rugby player with a 2-year history of left calf swelling and intermittent pain and tightness. He described a previous history of 2 left sided lumbar micro-discectomy surgeries. There was no tenderness or sensory deficit on examination. MRI of the left calf revealed muscular enlargement, with fat interspersed between the muscle fibers, in keeping with pseudohypertrophy. This has a number of causes, in this cause attributed to lumbar radiculopathy. This case highlights a rare but important cause of limb swelling which should be considered in the workup of a unilateral swollen limb.

Jugular foramen tumour resulting in hypoglossal denervation pseudohypertrophy: a rare and significant cause for tongue asymmetry

Paragangliomas of the jugular foramen are rare. They may present with symptoms of compression of the glossopharyngeal or vagus nerves, or due to secretion of catecholamines from chromaffin cells within the tumour. This case describes a rare presentation of glomus tumour. A 67-year-old patient presented with a 2-month history of right-sided tongue swelling. She was found to have an obvious swelling on the right side of the tongue but no obvious weakness or fasciculation on initial examination. Ultrasound confirmed diffuse muscle swelling, but no lesion within the tongue. Magnetic resonance imaging of the neck revealed an ipsilateral glomus jugulare tumour that extended to the hypoglossal canal, and had resulted in ipsilateral denervation pseudohypertrophy of the lingual muscles. This paper reviews presentation of glomus jugulare tumours and contributes a novel presentation of a rare entity.