ABSTRACT
There is an imperative need for the early diagnosis of amyotrophic lateral sclerosis/motor
neuron disease (ALS/MND) in the current era of emerging treatments. When evaluating
the patient with ALS/MND, the neurologist must consider a number of other motor neuron
disorders and related motor syndromes that may have clinical features resembling ALS/MND.
The revised Airlie House-El Escorial diagnostic criteria have been established through
the consensus of experts meeting at workshops. However, by definition, using these
criteria a patient is likely to have fairly advanced disease at the time of a definitive
ALS/MND diagnosis. The reasons for the difficulty in making an early ALS/MND diagnosis
are several. No surrogate diagnostic marker currently exists for ALS/MND. ALS/MND
at its onset is heterogeneous in clinical presentation, its clinical course is variable,
and several clinical variants are recognized. In addition, certain motor syndromes,
such as monomelic amyotrophy, postpolio muscular atrophy, and multifocal motor neuropathy,
can clinically mimic ALS/MND. Therefore, not only may the diagnosis of ALS/MND be
clinically missed in the early stages, but worse, the patient may be wrongly labeled
as having ALS/MND. The diagnosis of ALS/MND requires a combination of upper motor
neuron (UMN) and lower motor neuron (LMN) involvement. Motor syndromes in which the
deficit is restricted to the UMN or LMN through the entire course of the disease are
described as atypical MND in this review. Approximately 5% of patients with ALS/MND
have overt dementia with a characteristic frontal affect. ALS/MND with parkinsonism
and dementia is rare outside the western Pacific region. The clinical course of motor
disorder in these overlap syndromes does not differ from that in typical ALS/MND.
KEYWORD
Atypical amyotrophic lateral sclerosis - motor neuron disease - progressive muscular
atrophy - spinal muscular atrophy - postpolio muscular atrophy - monomelic amyotrophy
- lathyrism - dementia
