Primary lateral sclerosis: further clarification
Introduction
In 1869, Charcot and Joffroy [1] in his formal description of ALS reported a syndrome, previously described by Türck, involving only the lateral column of the medulla, later named primary lateral sclerosis (PLS) by Erb [2]. The concept of PLS as a separate entity has always been challenged. Clinical criteria proposed by Stark and Moersch in 1945 [3] were reassessed in 1992 by Pringle et al. [4]. We reconsidered these criteria because of the possible involvement of the lower motor neuron, as suggested by many authors, [4], [5], [6], [7], [8], [9], [10], [11] and the lack of long-term follow-up in the study of Pringle et al. [4], who based their criteria on a single clinical and EMG study.
We carried out a preliminary prospective clinical, electrophysiological study in nine patients with a diagnosis of PLS to reassess the validity of those criteria.
Section snippets
Patients
This preliminary study was carried out in the ALS Center at the Salpêtrière Hospital, Paris. For 1 year, we isolated from our group of patients referred as ALS, nine patients who did not meet diagnostic criteria for definite, probable, or possible ALS [12], and presented all of Pringle's diagnostic criteria for PLS [4].
Clinical characteristics
The clinical characteristics of the patients are shown in Table 1. There were six men and three women, with a mean age at onset of symptoms of 56.6 years (range: 42–61 years), and a mean disease duration at first examination of 7.7 years (range: 3.6–12 years). The site of onset was the lower limbs in five patients, the upper limbs in one patient and bulbar in three. In all cases onset was insidious. Disease progression was very slow and four patients reported periods of stabilization lasting
Discussion
We carried out a preliminary prospective clinical and electrophysiological study in a subset of nine patients considered as PLS according to the criteria of Pringle et al. [4]. None of them fulfilled the criteria for definite, probable or possible ALS [12].
In all cases disease onset was insidious with a very slow progression, as reported by others [3], [4] and in contrast with ALS [17]. Most of our patients noted periods of stabilisation, which were sometimes of long duration, as also reported
Conclusion
Our clinical and laboratory results, taken in conjunction with those reported in post-mortem studies, lead us to consider that PLS belongs to the wide spectrum of motor neuron neurodegenerative diseases and we suggest that it could be a more “benign”, less evolutive form of amyotrophic lateral sclerosis.
Acknowledgements
We thank Frédérique Julien for technical assistance, the Association pour la Recherche sur la Sclérose Latérale Amyotrophique (ARS) for financial assistance.
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