a 74 year old woman visited our clinic , who had been suffering from pain in the low back and right lower limbs and right calf hypertrophy . six years ago , the patient had experienced low back pain and right 5 lumbar ( l5 ) radiating pain . at that time , the patient had been diagnosed as spinal stenosis between the 4 lumbar ( l4 ) and 5 lumbar ( l5 ) intervertebral space by lumbar spine magnetic resonance imaging ( mri ) and a hemi - laminectomy with interspinal device insertion had been done at another hospital . 5 years before the present visit , low back pain and right l5 and s1 radiating pain were developed . and she described her pain as a continuous dull pain in the low back area and along the right l5 and s1 dermatomes . this pain worsened while walking and was alleviated with rest . at the time of presentation , the patient 's pain level was 70/100 mm on visual analogue scale ( vas ) from 0/100 mm ( no pain ) to 100/100 mm ( worst pain imaginable ) . a physical examination showed 50% sensory loss along the right l5 and s1 dermatomes , using pin pricking and light touching . the 6-scale muscle strength test that goes from grade 0 ( no evidence of muscle contractility ) to grade 5 ( normal : complete range of motion against gravity with full resistance ) revealed decreasing power of ankle plantar flexion at grade 4 ( good : complete range of motion against gravity with some resistance ) out of 5 on the right side . in deep tendon reflex ( dtr ) , the knee jerk was normal ( 2+/2 + ) , however , ankle jerk on the right site was decreased ( 1+/2 + ) . the straight leg raising test showed a positive result at 45 in the right lower limb . the pulsation of the dorsalis pedis artery was normal . when we measured calf girth , the left side was 37 cm , while the right side was 42 cm . lumbar mri , lower extremity mri , electromyography ( emg ) and a nerve conduction velocity ( ncv ) test and laboratory test was done for diagnosis . in a recent lumbar mri , central and lateral canal narrowing was revealed central and lateral canal narrowing at the l4-l5 intervertebral space ( fig . 1 ) . a lower extremity mri that was done to confirm the reason for the right lower limb hypertrophy revealed a complete fatty change accompanying the right medial head of the gastrocnemius , and hypertrophy of the soleus ( fig . 2 ) . also , following electrodiagnostic examinations including electromyography ( emg ) and nerve conduction velocity ( ncv ) testing , the chronic state of right l5 and s1 polyradiculopathy was evident . the levels of creatinine kinase ( ck ) , ck - mb and alkaline phosphatase ( alp ) were normal respectively . we performed right an l5 , s1 selective transforaminal epidural block using , in each instance , 5 mg of triamcinolone and 2.5 ml of 0.5% mepivacaine for the low back pain and the right l5 , s1 radiating pain . pregabalin , a non - steroidal anti - inflammatory drug , and muscle relaxant were prescribed for 2 weeks . the low back pain and right lower limb radiating pain the low back pain and right leg pain were increased , as judged by a vas score of 50/100 mm . two weeks later , her pain was decreased to a vas score of 30/100 mm . we are still constantly observing the diameter of the right calf , which has not changed in the past 6 months . it is mostly caused by nerve root compression . among the body regions deformed by hypertrophy , calf hypertrophy can be caused by l5 , s1 nerve root compression , as in the present case . one posits that the hypertrophy is produced as a secondary result of chronic muscle stimulation . in a case that features chronic muscle stimulation , emg will reveal constant and abnormal complex repetitive discharges , such as myokymia , which is caused by the involuntary trembling of muscle fibers , and neuromyotonia , which involves peripheral nerve muscle fiber activity as a result of abnormal nerve stimulation . the second theory posits that hypertrophy of muscle fiber results from excessive exercise loading in the innervated muscle fiber . in the present case , the muscle weakness or decreased dtr the patient had mild muscle weakness consistent with a rank of grade 4 in ankle plantar flexion . the gastrocnemius and soleus are the muscles related with ankle plantar flexion , in which part of the innervation is from the tibial nerve from the s1 - 2 nerve root . we also discovered a sensory decrease from the dermatome , which is managed by l5 and s1 . according to the deep tendon reflex , there was decreased right ankle jerk with a 1 + lesion . to identify the result clearly , we performed lumbar spine mri which showed lateral canal narrowing central and lateral canal narrowing at the l4-l5 intervertebral space . the congruity of the imaging findings and the physical examination results indicate a high reliability of the final result . myopathic muscle hypertrophy is evident with a diffuse lesion , which is centralized on the muscle , not a nerve innervated lesion . conversely , neurogenic muscle hypertrophy is mostly an isolated muscle innervated by an abnormal nerve . to confirm the lesion on the right calf muscle hypertrophy characterized by fatty change and pseudohypertrophy was focused on the gastrocnemius and soleus . myopathic muscle hypertrophy increases muscle enzymes ( ck , ck - mb , alp ) , but in neurogenic hypertrophy the increase is mild , or the levels remains normal . in this case , there was a normal level from muscle enzyme test . according to the history of the patient , there was no particular muscular and metabolic disease , or excessive exercise history . according to the emg and nerve conduction velocity results , we could not confirm any decreased duration of motor unit potential , which is the most sensitive and specific parameter in myopathic muscle hypertrophy . in this case , right l5 and s1 polyradiculopathy was noted . the collective observations supported the diagnosis as neurogenic muscle hypertrophy . among the various causes of neurogenic muscle hypertrophy , such as anterior horn cell disease , plexopathy , sciatic nerve injury , and polyneuropathy , we can confidently conclude that l5 , s1 nerve roots compression caused the sustained and exacerbated symptoms in this patient . neurogenic muscle hypertrophy shows increased size and number of muscle fibers , internal nucleation , fiber splitting and disruption of intermyofibrillar architecture in muscle biopsies on the affected muscles . treatment can involve surgery or can be nonsurgical . in nonsurgical treatment , an injection of botulinum toxin   and steroid medication   are effective . in surgical treatment , gibson and waddell   reported that microdiscectomy is the effective way to reduce radiculopathy and muscle hypertrophy . in the present case , we performed a right l5 , s1 selective transforaminal epidural block to relieve right l5 , s1 radiating pain . after that , radiating pain was relieved and patient was informed about the disease and further management . we found that the selective transforaminal epidural block decreased pain , but was not enough to improve the calf muscle hypertrophy . in conclusion , muscular hypertrophy has a myopathic cause and a neurogenic cause . to discriminate between these , a proper neurologic examination and laboratory tests such as muscle enzyme test , emg , mri , and muscle biopsy are needed . neurogenic muscle hypertrophy is very rare , but we recommend clinicians consider this problem when patients complain of lower limb hypertrophy and pain .
muscular hypertrophy is caused mainly due to myopathic disorder . 
 but , it is also rarely produced by neurogenic disorder . 
 a 74-year - old woman complained of right calf pain with hypertrophy for several years . 
 recent lumbar spine magnetic resonance imaging ( mri ) showed central and lateral canal narrowing at the l4-l5 intervertebral space . 
 lower extremity mri revealed fatty change of right medial head of the gastrocnemius and soleus , causing right calf hypertrophy . 
 electrodiagnostic examinations including electromyography and nerve conduction velocity testing demonstrated 5th lumbar and 1st sacral polyradiculopathy . integrating all the results , the diagnosis was neurogenic muscle hypertrophy . 
 neurogenic muscle hypertrophy is very rare , but we recommend that clinicians consider this problem when a patient complains of lower limb hypertrophy and pain .