Article

Hereditary spastic paraplegias (HSPs) are a group of rare inherited neurological
diseases characterized by extreme heterogeneity in both their clinical
manifestations and genetic backgrounds. Based on symptoms, HSPs can be divided
into pure forms, presenting with pyramidal signs leading to lower-limb
spasticity, and complex forms, when additional neurological or extraneurological
symptoms are detected. The clinical diversity of HSPs partially reflects their
underlying genetic backgrounds. To date, 76 loci and 58 corresponding genes
[spastic paraplegia genes (SPGs)] have been linked to HSPs. The genetic diagnosis
is further complicated by the fact that causative mutations of HSP can be
inherited through all possible modes of transmission (autosomal-dominant and
-recessive, X-linked, maternal), with some genes showing multiple inheritance
patterns. The pathogenic mutations of SPGs primarily lead to progressive
degeneration of the upper motor neurons (UMNs) comprising corticospinal tracts.
However, it is possible to observe lower-limb muscle atrophy and fasciculations
on clinical examination that are clear signs of lower motor neuron (LMN)
involvement. The purpose of this review is to classify HSPs based on their degree
of motor neuron involvement, distinguishing forms in which only UMNs are affected
from those involving both UMN and LMN degeneration, and to describe their
differential diagnosis from diseases such as amyotrophic lateral sclerosis.
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Langue : ANGLAIS