Since upper motor neurons are not affected, upper motor neuron signs such as rigidity do not occur.
[verywell.com]
Upper motor neuron signs were not found, but five had mild pes cavus, three had moderate hammer toes, and one had pes planus, consistent with longstanding neurogenic disease
[ahcmedia.com]
[…] units -muscle biopsy shows atrophic fibers & fiber grouping -seen in MRI -present: lower motor neuron signs in upper extremities secondary to nerve root compression & upper
[brainscape.com]