The broad clinical spectrum of hereditary neuropathy with liability to pressure palsy (HNPP).

editorial The broad clinical spectrum of hereditary neuropathy with liability to pressure palsy (HNPP) H ereditaty neuropathy with liability to pressure palsy (HNPP) is an autosomal dominant neuropathy encompassing a broad clinical phenotype spectrum, which usually makes its diagnosis difficult in an exclusive clinical basis. Recurrent sensory and motor neuropathy in a single nerve beginning in adolescence or young adulthood is characteristically seen. In most cases this recurrent clinical evolution is due to a PMP22 gene deletion. Mononeuropathies resulting from nerve pressure in entrapment points are the most common presentation, but an almost symmetric polyneuropathy can eventually be seen 1. Suggestive electrophysiological findings that draw attention for HNPP diagnosis are in consideration. DNA mutations tests are diagnostic, but not always available. Although it is an autosomal dominant condition, family history can be lacking in many cases, especially in Brazil, a country with a strong migration process and with different ethnics groups. In a recent comparison of causes of neuropathy in peripheral neuropathy reference centers in the United State of America and South-America (NA-SA project) we have observed a higher percentage of diagnoses of inherited neuropathies in the USA in comparison with Brazil: NA 292 (26.7%), SA 103 (10%) 2. In an American international reference center of inherited neuropathy an epidemiological study, including 787 Charcot-Marie-Tooth disease (CMT) patients, showed that only 67% received molecular diagnosis 3. This result points that the diagnosis is performed mainly in clinical/ neurophysiological basis. This edition of Arquivos de Neuropsiquiatria includes an elegant study by Oliveira et al. 4 reporting the clinical and neurophysiological features of HNPP due to the 17p11.2 deletion in 39 Brazilian patients, looking for its diagnostic characteristics. In this series, family history was present in 59% of cases, showing that clinical presentation, recurrence of signs and symptoms , and neurophysiological findings are strong elements for diagnostic suspicion. A progressive course is uncommon, but was reported in 20% of their HNPP patients 4. Older presentation of HNPP was seen in this series, in contrast with others. The first clinical manifestation was the classical painless muscle weakness with at least one episode of acute nerve paralysis (61,5% of cases). This painless acute or subacute mononeuropathy is the classical phenotype 1. Pes cavus and nerve thickening, seen in CMT patients, was rare in Oliveira et al. 4 HNPP series. Heterogeneity in clinical presentation and disease course is the rule in this neuropathy 1,5. Atypical presentations …