Clinically undetected motor neuron disease in pathologically proven frontotemporal lobar degeneration with motor neuron disease.
BACKGROUND
Frontotemporal lobar degeneration with motor neuron disease (FTLD-MND) is a pathological entity characterized by motor neuron degeneration and frontotemporal lobar degeneration. The ability to detect the clinical signs of dementia and motor neuron disease in pathologically confirmed FTLD-MND has not been assessed.


OBJECTIVE
To determine if all cases of pathologically confirmed FTLD-MND have clinical evidence of frontotemporal dementia and motor neuron disease, and to determine the possible reasons for misdiagnosis.


METHODS
Review of historical records and semiquantitative analysis of the motor and extramotor pathological findings of all cases of pathologically confirmed FTLD-MND.


RESULTS
From a total of 17 cases of pathologically confirmed FTLD-MND, all had clinical evidence of frontotemporal dementia, while only 10 (59%) had clinical evidence of motor neuron disease. Semiquantitative analysis of motor and extramotor pathological findings revealed a spectrum of pathological changes underlying FTLD-MND. Hippocampal sclerosis, predominantly of the subiculum, was a significantly more frequent occurrence in the cases without clinical evidence of motor neuron disease (P<.01). In addition, neuronal loss, gliosis, and corticospinal tract degeneration were less severe in the other 3 cases without clinical evidence of motor neuron disease.


CONCLUSIONS
Clinical diagnostic sensitivity for the elements of FTLD-MND is modest and may be affected by the fact that FTLD-MND represents a spectrum of pathological findings, rather than a single homogeneous entity. Detection of signs of clinical motor neuron disease is also difficult when motor neuron degeneration is mild and in patients with hippocampal sclerosis.
Josephs
Keith A
KA
Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA. josephs.keith@mayo.edu
Parisi
Joseph E
JE
Knopman
David S
DS
Boeve
Bradley F
BF
Petersen
Ronald C
RC
Dickson
Dennis W
DW
D000328:Adult; D017668:Age of Onset; D000368:Aged; D001921:Brain / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D003704:Dementia / Q000150:complications* / Q000175:diagnosis* / Q000503:physiopathology; D003937:Diagnosis, Differential; D003951:Diagnostic Errors / Q000517:prevention & control; D018450:Disease Progression; D042241:Early Diagnosis; D005260:Female; D005911:Gliosis / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology; D006624:Hippocampus / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D002479:Inclusion Bodies / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D016472:Motor Neuron Disease / Q000150:complications* / Q000175:diagnosis* / Q000503:physiopathology; D009046:Motor Neurons / Q000378:metabolism / Q000473:pathology; D009410:Nerve Degeneration / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology; D011237:Predictive Value of Tests; D011712:Pyramidal Tracts / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D012189:Retrospective Studies; D013116:Spinal Cord / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology