The natural history of primary lateral sclerosis

Abstract

Clinically pure PLS can be defined by isolated UMN signs 4 years after symptom onset, and is a syndrome of slow progression with high levels of function. Prior to the fourth year, the diagnosis of PLS cannot be made with certainty because many patients develop LMN signs. UMN-dominant ALS, defined by predominantly UMN disease with minor LMN signs, has disability similar to ALS, but slower progression.

The phenotypic variability of amyotrophic lateral sclerosis

“…These patients are considered to have primary lateral sclerosis (PLS); however, most of these individuals gradually develop lower motor neuron involvement. 44,45 The diagnosis of PLS can, therefore, only be made after a sufficiently long period of observation, as 23% of those who eventually develop lower motor neuron signs do so only after 4 years. 44 PLS constitutes about 5% of all cases of MND.…”

“…44,45 The diagnosis of PLS can, therefore, only be made after a sufficiently long period of observation, as 23% of those who eventually develop lower motor neuron signs do so only after 4 years. 44 PLS constitutes about 5% of all cases of MND. 46 This condition is characterized by slower progression, moreprolonged retention of functionality, sparing of respiratory function and less-severe weight loss than seen in ALS.…”

“…47 The mean survival of ALS patients with predominant upper motor neuron signs-6 years, with about 30% of cases exhibiting long-term (>10 years) survival-lies between that of PLS and classic ALS. 6,44 This difference may simply reflect the biological burden of disease ( Figure 5). It also implies that the best approach is to study patients with both lower and upper motor neuron involvement only if one intends to (prognostically) homogenize a study population, as is needed, for example, in clinical trials that investigate the effects of a drug on function or survival.…”

Combined 3T Diffusion Tensor Tractography and1H-MR Spectroscopy in Motor Neuron Disease

“…1 Classic ALS affects the upper (UMN) and lower motor neurons (LMN), but cases with predominant UMN or LMN involvement also occur. It is still debated whether primary lateral sclerosis (PLS) and ALS are distinct disorders or manifestations of a single disorder, and a classification into ALS, UMN-dominant ALS, and PLS has been proposed to systematize future trials, 2 hence the correctness of UMN assessment is crucial.…”

Associations Between Laryngeal and Cough Dysfunction in Motor Neuron Disease with Bulbar Involvement

“…21 Similar to ALS, initial focal degeneration in PLS occurs in the limbs for most, but can also begin in the bulbar musculature. 29 Owing to the UMN involvement, muscle spasticity and slowness is common in this group.…”