O'Sullivan-McLeod syndrome: Unmasking a rare atypical motor neuron disease.

Atypical motor neuron disease represents a rare heterogeneous group of neurodegenerative disorders with clinical, genetic and neuroimaging features distinct from those of the classic spinal or bulbar-onset amyotrophic lateral sclerosis (ALS). O'Sullivan-McLeod syndrome represents an extremely rare lower motor neuronopathy with early adult-onset distal amyotrophy and weakness in the upper limbs with asymmetrical involvement. To add to the few case series and epidemiological and genetic studies describing this variant syndrome, our team here presents a series of seven unrelated Brazilian patients with O'Sullivan-McLeod syndrome in a detailed review of their clinical, neuroimaging, laboratory and neurophysiological findings. A male-to-female ratio of 2.5 to 1 and a mean age at onset of 34.3years was observed, with a mean time delay of 6.6years between symptom-onset and a definitive diagnosis. A positive family history was observed in one case, yet whole-exome sequencing results were negative. Neuroimaging studies were unremarkable. All cases presented with chronic denervation restricted to cervical myotomes and normal sensory nerve conduction studies. This case series, one of the largest groups of patients with O'Sullivan-McLeod syndrome reported in the literature, confirms the sporadic nature of the condition and the difficulties faced in arriving at a definite diagnosis, and also expands the age limit in late adult-onset cases.

[Juvenile amyotrophic lateral sclerosis. Apropos of a case]. / Esclerosis lateral amiotrófica juvenil. A propósito de un caso.

INTRODUCTION: There are scanty reports on juvenile forms of amyotrophic lateral sclerosis, specially amyotrophic lateral sclerosis and deafness, and it is known as Madras pattern of motor neurone disease. CLINICAL CASE: We describe an sporadic case of juvenile amyotrophic lateral sclerosis with deafness in a young person who started with hearing loss at 21 years old, loss of strength in upper limbs and muscular atrophy. He was seen by a neurologist when he was 25 years old, there were evident generalized fasciculation activity in proximal and distal muscles in the four limbs and the tongue, with swallowing troubles, and increased tendon reflexes in lower limbs with abnormal plantar extensor responses. All the paraclinical test were normal, except the electromyogram, showing a classical pattern of lower motor neuron disease, and the auditory brain stem response with absence of the main components of this evoked response, as expression of VIII cranial nerve damage. DISCUSSION: Patients like this one were first described in Madras (India), and the evolution of this kind of juvenile form of amyotrophic lateral sclerosis is chronically progressive and relative benign, in relation to the classical form of amyotrophic lateral sclerosis and other forms of motor neurone disease which begin in childhood, adolescence or young adulthood. CONCLUSION: Its recognition is very important in order to diminish misleading therapies in these patients.