generally , lumbar disk herniation ( ldh ) with foot drop is an indication for early decompressive surgery7 ) . however , even for cases of painless foot drop or foot drop with numbness , examinations are necessary to distinguish them from other diagnoses including peroneal nerve palsy , sciatic nerve mononeuropathy , lumbosacral plexopathy , polyneuropathy , and severe l5 radiculopathy1,5 ) .
we report here an unusual case of charcot - marie - tooth ( cmt ) disease initially presenting with unilateral foot drop with foot numbness .
a 57-year - old woman , presenting with left leg weakness and foot numbness , visited our hospital for surgery after being diagnosed with ldh at a local hospital .
the patient was treated with neuroplasty twice at the local hospital , but did not show symptom improvements .
left ankle dorsiflexion weakness ( grade iii ) and knee extension weakness ( grade iv ) with foot numbness were observed .
additionally , we found foot deformity ( muscle atrophy , high arch , and clawed toes ) ( fig .
1 ) . mri of the lumbar spine showed ldh at l4 - 5 ( fig .
her neurological status and symptoms were not correlated with l5 radiculopathy . to obtain a differential diagnosis , we performed further examinations . to evaluate neuropathy or myopathy
electrophysiological findings were consistent with chronic peripheral motor - sensory polyneuropathy ( axonopathy ) . the neurologist presumed cmt disease and recommended a genetic test or nerve biopsy for its confirmation . in genetic testing , the 17p11.2-p12 duplication / deletions characteristic of cmt disease were observed .
cmt disease is a peripheral neuropathy and a subtype of hereditary motor - sensory neuropathies ( hmsn)9,10 ) .
it is the most common type of inherited polyneuropathy , with a prevalence estimated at up to 40 individuals in every 1000001,9 ) .
cmt disease is distinguished from the demyelinating type , hmsn type 1 , from axonal hmsn type 26,9,14,15 ) .
both hmsn types are genetically heterogeneous , resulting from various genetic defects3 ) , the most common being duplication or deletion of the peripheral myelin protein gene ( pmp-22 ) gene at chromosome 17 , which results in either phenotype1,4,6,9,15 ) .
clinically , cmt patients often initially present symmetrical distal predominance of limb - muscle wasting , weakness , and sensory loss , especially in the lower extremities9,10,15 ) .
motor symptoms from the feet include pes cavus ( or pes planus ) ( fig .
1 ) , hammer toes , difficulty in running , walking , twisting of the ankle , tripping , foot drop , steppage gait , wasting , and weakness9,10,13 ) .
hand tremor , muscle cramps , cold feet , and acrocyanosis are other common signs9 ) .
positive sensory symptoms such as paresthesia , numbness , and radiating pain are common , leading to operations based on misdiagnoses9 ) .
deep tendon reflexes are reduced or absent following the same distal to proximal gradient , and some patients have skeletal deformities , including scoliosis9,10,13 ) . because these symptoms are similar to complaints in patients with spinal myelopathy or radiculopathy , spine surgeons could misdiagnose a patient with cmt disease . for diagnosis , clinical findings and identification of hereditary patterns
could be useful , of which autosomal - dominant inheritance is the most common pattern9,13,14,15 ) .
it is important to bear in mind that x - linked charcot - marie - tooth ( cmtx1 ) , transmitted as an x - linked dominant trait , is characterized by no male - to - male transmission9,13,15 ) .
electrophysiological studies should be performed to assess the presence , degree , and pattern of nerve - conduction slowing .
electrophysiologically , cmt1 is a uniform , diffuse demyelinating neuropathy with marked slowing of nerve conduction velocities ( < 38 m / s in upper - limb motor nerves)3,8,9,10,15 ) .
cmt2 , on the other hand , shows less severe conducting slowing and may even exhibit no such slowing at all ( > 38 m / s ) in cmt23,9,14,15 ) . additionally , molecular tests are necessary to confirm cmt .
however , dna testing needs to take into account the fact that there are numerous genes associated with cmt1,14 ) . in autosomal - dominant or sporadic cmt with electrophysiological evidence of demyelination
, cmt1a duplication should be investigated first , followed by consideration of cmtx1 and mutations in gap junction -1 protein .
if cmt2 is diagnosed , molecular tests should be directed toward mitofusin-2 and myelin protein zero9,10,11,13 ) .
nerve biopsy shows characteristic focal hypermyelination involving many internodes that cause segments of thickened myelin resembling links of sausage ( tomaculi ) , hence its original name of tomaculous neuropathy9,15 ) .
spine surgeons should be aware that painless foot drop or foot drop with nonspecific numbness could be caused by peroneal nerve palsy , sciatic nerve mononeuropathy , lumbosacral plexopathy , polyneuropathy , and severe l5 radiculopathy1,10 ) .
these diseases should be excluded expeditiously , because severe cases of ldh could show progressing weakness coupled with a gradual reduction of pain . in our case ,
the patient had extruded ldh , which confused the cause of the foot drop for physicians at a local hospital .
indeed , elderly or middle - aged patients may have asymptomatic ldh or stenosis2,12 ) ; we should therefore be cautious about deciding on spine surgery for patients with a degenerative spine .
when we treat patients with painless foot drop or foot drop with numbness , we recommend careful diagnosis .
it is necessary to distinguish between various diseases , such as peripheral neuropathy and severe radiculopathy .
in addition , cmt should be considered as a cause , although its incidence is rare , because its various symptoms are similar to spinal disease or peripheral neuropathy .
 we report the case of 57-year - old woman diagnosed with charcot - marie - tooth ( cmt ) disease and lumbar disk herniation ( ldh ) . 
 she had left leg weakness and foot numbness , foot deformity ( muscle atrophy , high arch , and clawed toes ) . 
 the lumbar spine mri showed ldh at l4 - 5 . additionally , electrophysiology results were consistent with chronic peripheral motor - sensory polyneuropathy ( axonopathy ) . 
 in genetic testing , 17p11.2-p12 duplication / deletions characteristic of cmt disease were observed . 
 we confirmed the patient 's diagnosis as cmt disease and used conservative treatment . 
INTRODUCTION
CASE REPORT
DISCUSSION
CONCLUSION