neuropathy was a nosological entity under development exactly
during this period, and the debate over the Ajuda paralyses coin-
cides in time with the recognition of the new category of neuro-
logical diseases of the peripheral nerves. The existence of diseases
affecting several peripheral nerves simultaneously, or ‘multiple
neuritis’, would only be proposed by Ernst von Leyden
(1832–1910) in 1874 (von Leyden, 1874). Previously, in 1843,
Robert Graves (1797–1853) had already anticipated that lesions
in peripheral nerves could cause paralysis and sensory dysfunction
of the limbs in his comments on the Paris acrodynia epidemic: ‘The
French pathologists, you may be sure, searched anxiously in the
nervous centres for the cause of this strange disorder, and could
find none; there was no evident lesion, functional or organic, dis-
coverable in the brain, cerebellum or spinal marrow [. . .] Can
anyone [. . .] hesitate to believe that paralysis [. . .] may arise
from disease commencing and originating in the nervous extremi-
ties alone?’ (quoted from Pearce, 1990). Also, about the
same time, in 1859, Jean Baptiste Octave Landry de The´izillat
(1826–65) had published the first volume of his Traite´ complet
des paralysies and his work on ascending paralysis, and 5 years
later Louis Dume´nil (1823–90) would confirm the presence of
lesions of the peripheral nerves in such patients (Brody et al.,
1994; Pearce, 1997). It is curious that although the Portuguese
physicians knew of Graves’s work (quoted, for example, by Gomes
and Barbosa), none mentioned the possibility of a peripheral nerve
lesion in the Ajuda cases.
Is it possible today to propose an alternative interpretation for
the events in the Ajuda asylum between 1860 and 1864?
Assuredly, given the uncertainties regarding the true clinical char-
acteristics of the outbreaks, the easiest explanation may be simply
to invoke the all-encompassing label of somatization disorder, epi-
demic hysteria or mass sociogenic illness. But although single epi-
sodes of motor paralysis of psychosomatic (functional) cause are
relatively common in neurological practice, what is the evidence
regarding multiple simultaneous cases? In a thorough historical
review of such events, Sirois collected and systematized the
main characteristics of 78 epidemic hysteria outbreaks between
1872 and 1972 (including a reference to Jorda˜o’s publication)
(Sirois, 1974). In his classification, the Ajuda paralyses would
belong to the category of cumulative outbreaks in which clinical
manifestations typically involve less than 10 persons, in institution-
al environments and develop over 2 weeks to 1 month. Overall,
the largest number of cases of epidemic hysteria in this series
occurred in schools (n = 34), involved between 10 and 20 people
(n = 25), below 20 years of age (n = 41), in females (n = 58) and
lasted from 3 to 14 days (n = 28). That seems to partially fit with
the profile of the Ajuda epidemics, with the exception that long
duration (over 1 month) outbreaks are more rare (n = 15).
However, symptoms clearly differ: seizures (n = 19), abnormal
movements (n = 14), fainting (n = 9) and paresthaesia and anaes-
thesia (n = 9) were the most common, whereas outbreaks of
paralysis were much less frequent (only three cases, 4% of the
total). In a more recent work, in which 70 outbreaks from 1973 to
1993 were studied, there are no major changes in their general
characteristics, but the clinical manifestations change slightly; the
percentage of paralysis cases increases to 11% (n = 7) and there is
a complete disappearance of seizures and abnormal movements
(Boss, 1997). It is well known that social and cultural influences
throughout time have a significant impact on clinical manifest-
ations of mass sociogenic illness (Bartholomew and Wessely,
2002). We can conclude from these reviews that epidemics of
hysteric paralysis are not common now and were even less so in
the
19th
century,
leaving
the
field
open
to
alternative
explanations.
So far we have focused mainly on the paralysis outbreaks,
which may or may not have been caused by hysterical conversion.
However, it is much less probable that the epidemic of vomiting,
which affected nearly the totality of the subjects (90% of the
resident population), might also be due to the same cause.
Even in hyperemesis gravidarum, a well-recognized phenomenon
in pregnant women and one of the most common causes of
recurrent vomiting, support for a psychosomatic causation has
decreased
markedly
in
recent
years
(Goodwin,
2008).
Furthermore, it is hard to accept that ‘hysterical’ vomiting, even
if present in non-pregnant young females and males, could
assume epidemic proportions and be maintained throughout
such a prolonged period of time. Epidemic vomiting is usually
related to gastrointestinal infections (e.g. winter vomiting disease
caused by Norwalk virus infection) or intoxications. With that in
mind, an interesting piece of evidence, briefly mentioned by
Gomes, is that the vomiting epidemic was transmitted to another
institution (the Junqueira asylum) when some of the affected chil-
dren were transferred there (Gomes, 1865a). This clearly points to
an infectious cause, which also fits in with the poor hygienic con-
ditions and overcrowding in the Ajuda asylum.
Finally, there remains to explain the epidemic of night blindness,
or haemeralopia. As we saw, the clinical characteristics of these
patients were best described by Joa˜o Clemente Mendes, who
highlighted the presence of both haemeralopia and xerophtalmia,
and compared his findings to what Charles Deval (1806–62), in his
1844 Traite´ de Chirurgie Oculaire, had called xeroma. The con-
current observation of night blindness and conjunctival dryness
would be repeated 3 years later by Pierre Bitot (1822–88), who
left his name connected with the patches of keratinized metaplasia
in the bulbar conjunctiva that are nowadays considered pathog-
nomonic of vitamin A deficiency. In fact, Mendes’s work has been
referred to as one of the first descriptions of avitaminosis A,
together with those by Mecklenburg in 1855 and Anton von
Huebbenet (1822–73) in 1860 (Semba, 2007). Taking into
consideration the dietary deficiencies pointed out by Jorda˜o, it is
not strange that such cases could have appeared in the Ajuda
asylum.
In fact, nutritional deficits could also have been at the root of
the outbreaks of paralysis, since we now know that vitamin defi-
ciencies are frequent causes of peripheral nerve damage.
Historically, the first description of a polyneuropathy was
made (posthumously) in 1642 by Jacob de Bondt [Bontius
(1592–1631)] in beri-beri patients (Pearce, 1990), and the Paris
acrodynia epidemic was compared from the start to the manifest-
ations of pellagra, as Gomes also points out (Gomes, 1865a;
Wood, 1921). Furthermore, at the end of the 19th-century
Henry Strachan described an epidemic of sensory and optic neur-
opathy, ataxia, hearing problems, cortico-spinal dysfunction and
stomatitis in Jamaican sugar cane workers (afterwards named
The ‘Ajuda Paralyses’
Brain 2010: 133; 3141–3152
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