Early limb paralysis in infants: do not forget about congenital syphilis

Introduction

Congenital syphilis is a potentially serious infection caused by mother-to-child transmission of Treponema pallidum. Affected infants can have long-term consequences, involving growth failure and severe disorders in neurological and skeletal development. ¹ This infection can be prevented with appropriate prenatal screening and treatment during pregnancy.

Congenital syphilis rates in European countries have been decreasing over the past two decades, probably because of the improvement of prenatal screening programs.^2,3 However, a new increase in notified cases was reported in 2018, with a rate of 1.6 cases per 100,000 live births.^2–4 Furthermore, under-reporting of congenital syphilis still represents an issue.^2,3

Case report

We report the case of a 2-month-old male baby born at term, who was admitted to our tertiary care children’s hospital for investigation of the subacute onset of right arm paralysis. His parents were of Peruvian origins living in Italy, where the baby was born.

At one month of age, he presented with irritability, impaired sleeping, and hypomobility of both upper limbs, which then became limited to the right arm. He had no history of fever and trauma. Subsequently, he began to show difficulties in breastfeeding, with long breaks during feeding, without cyanosis or sweating.

At admission, he was febrile and had a maculopapular rash on the sole of the left foot and on the right arm. The right upper limb was painful on physical examination, and the neurological evaluation suggested a brachial plexopathy.

Blood examination showed increased inflammatory markers (C-reactive protein (CRP) 7.25 mg/dL), increased liver enzymes (aspartate transaminase (AST) 149 IU/L; alanine aminotransferase (ALT) 180 IU/L), and normal synthetic liver function. The X-ray of the limb showed periosteal apposition on the metaphysis and the proximal diaphysis of the radius and ulna. A similar finding was detected at the distal humerus.

Suspecting osteomyelitis, antibiotic therapy with ceftazidime and oxacillin was started.

In light of the hypertransaminasemia, infection by hepatotropic viruses (Epstein–Barr virus, cytomegalovirus, hepatitis B and C viruses, and HIV) was excluded. Furthermore, pathogens potentially responsible for osteomyelitis at this age (Staphylococcus aureus, Streptococcus pyogenes, Streptococcus agalactiae, Escherichia coli, and Listeria monocytogenes) were searched for by polymerase chain reaction on blood samples, with negative results. Total body magnetic resonance imaging showed periosteal striped thickening throughout the right radius and the ulna and on the metaphysis of the humerus (Figure 1); other similar findings were observed in the contralateral upper limb, corroborating the hypothesis of a systemic infection.OPEN IN VIEWER

Clinical and radiological findings suggested a congenital syphilis with pseudoparalysis of Parrot, although maternal serology during the first trimester of pregnancy had been negative.

A complete syphilis serology was performed on the infant, including treponemal and nontreponemal tests (Table 1). Congenital syphilis was diagnosed on the basis of a positive panel.

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Table 1.

Serologic results at diagnosis and 6 months after treatment.

Serology	At diagnosis	6 months after treatment
Treponema pallidum hemagglutination (TPHA)	Positive 1:80	Positive 1:640
Rapid plasma reagin (RPR)	Positive 1:64	Negative
Treponema pallidum IgG–IgM	Positive	Positive
Fluorescent treponemal antibody absorption	IgG + + + −	IgG + + − −
	IgM + − − −	IgM − − − −

Serology was also performed in his parents. The mother showed positive Treponema pallidum hemagglutination (TPHA) and a rapid plasma reagin (RPR) title of 1:64. She presented Examination demonstrated a lesion on the palm of her hand, consistent with secondary syphilis. The father had positive TPHA and a RPR title of 1:8. He reported having had a penile lesion during his partner's second trimester of pregnancy, which had spontaneously healed (thus possibly consistent with chancre).

A lumbar puncture was performed in the child, as recommended by international guidelines. The analysis of cerebrospinal fluid (CSF) showed RPR titre 1:1 and negative TPHA. The CSF was hemorrhagic because of a traumatic lumbar puncture; therefore, the positive RPR was interpreted as a false positive result. Moreover, this would not have affected the duration and the dosage of the therapy. ⁵

The child underwent intravenous antibiotic therapy with penicillin 50,000 international units/kg 6 times a day for 10 days with subsequent normalization of inflammation (CRP) and liver enzyme indices (AST and ALT) and progressive improvement of the motility of the right arm.

A multidisciplinary outpatient follow-up was started, involving infectious diseases specialists, physiotherapists, and orthopedics. Serology showed negative nontreponemal tests 6 months after treatment (Table 1).

Discussion

The diagnosis of congenital syphilis is challenging because of its heterogeneous clinical presentation. Skeletal involvement is frequent. Typical signs are periosteal thickenings of long bone metaphyse, which can lead to pseudoparalysis of Parrot. ¹

In the reported case, clinical and laboratory features were not specific and might have been suggestive of an acute osteomyelitis. On the other hand, radiological signs were strongly suggestive of pseudoparalysis of Parrot, but the negative results of prenatal screening for Treponema pallidum infection may have caused a delayed diagnosis.

Screening of syphilis during the first trimester of pregnancy is strongly recommended by most countries^2,3,7. A second screening later in pregnancy is offered only by countries with high rates of congenital syphilis, such as those in Eastern Europe.^2,3,6,7

In other countries, a second test is offered to women at risk, such as migrant women and women engaging in high-risk behaviors (drug addiction, multiple sex partners, and HIV infection).^2–4,6–8 Clinicians have a crucial role in the detection of risk factors during pregnancy and in prevention strategies. In countries where only first trimester screening is recommended, it is very important that women are given advice about safe sex in pregnancy. If there is deemed to be risk of infection, second testing for syphilis and other infections should be undertaken.

However, it may be very difficult to identify all the women who really need this second screening. Furthermore, some women might have poor knowledge about healthcare services because of language barriers. A lack of consciousness of the importance of maternal health may also be due to cultural differences. These factors are likely to be responsible for a further increased risk of maternal infections.^2–4,6–8

This case highlights the need for a major awareness of this disease and supports the opportunity of a second screening in high-risk groups of women.^7,8

It is fundamental to diagnose all cases of congenital syphilis and to notify them to public health for epidemiological purposes. Finally, national observational studies are needed to identify mothers’ risk factors for congenital syphilis, in order to tailor the second screening accurately.