Immobile Left Arm in a 2-month-old Infant

A 2-month-old boy presents to a community emergency department (ED) with 1 week of fussiness and decreased left arm movement. The evaluating provider orders radiographs of the upper extremity that show heterogenous lucencies in the proximal radius and ulna suggestive of subacute trauma or infection. These findings prompt transfer of the patient to a pediatric facility to evaluate for nonaccidental trauma (NAT). His mother, who is his sole caregiver, reports no history of trauma, swelling, or discoloration of the extremity. The infant has some congestion, which his mother believes has been present for 1 month. Review of systems is negative for fevers, cough, lethargy, vomiting, or diarrhea. The family lives in a communal setting in a shelter, but his mother reports no specific sick contacts. He is exclusively formula fed and has been feeding well. At a routine health supervision visit 2 weeks ago, his growth and development were appropriate.His mother received routine prenatal care. Her first-trimester human immunodeficiency virus and syphilis screening tests were negative, as was group B streptococcus screening at the time of delivery. The prenatal course was complicated by substance use disorder, preeclampsia, and a first-time outbreak of herpes simplex virus. The latter 2 complications prompted a cesarean delivery at 35 weeks. Delivery was uncomplicated, with Apgar scores of 8 and 9 at 1 and 5 minutes, respectively. On day 2 after birth, the infant developed poor feeding, hypoglycemia, and hypothermia. The infant was transferred to the NICU for evaluation of infection versus methamphetamine withdrawal. The infectious evaluation was negative, and he was treated for neonatal abstinence syndrome. After 16 days in the NICU, he was discharged home to his mother with ongoing Child Protective Services (CPS) involvement due to maternal substance use.On physical examination in the ED, he is afebrile and has normal vital signs for age. His growth parameters are appropriate for age. He does not appear to be in distress. Disconjugate gaze is noted, which his mother reports has been present since birth. There is clear rhinorrhea. The left upper extremity has normal passive range of motion but no spontaneous movement. The left forearm is slightly swollen and minimally tender to palpation. His tone is low overall, with notable head lag and poor suck reflex, but he feeds from a bottle without difficulty. Skin is notable for two 1-cm circular crusted lesions on the left upper and lower extremities (Fig 1). There is no bruising present.Due to the concern for an unexplained fracture in a premobile infant, a skeletal survey is ordered, and the child abuse team is consulted. Initial laboratory work reveals elevated liver enzyme levels (aspartate aminotransferase level, 202 U/L [3.37 µkat/L]; alanine aminotransferase level, 222 U/L [3.71 µkat/L]) and a complete blood cell count notable for anemia (hemoglobin level, 8 g/dL [80 g/L]), with normal platelet (202 × 103/µL [202 × 109/L]) and leukocyte (11,600/µL [11.6 × 109/L]) counts. Additional evaluation is initiated to explore other explanations for the child’s presentation, including toxic ingestion, infectious etiology, or underlying metabolic disorder. Venous blood gas, basic metabolic panel, and urinalysis are within normal limits. Extended urine toxicology screen and respiratory viral panel are negative. C-reactive protein level is elevated to 4.8 mg/dL (48 mg/L). Blood cultures, urine cultures, and a lumbar puncture are obtained. The skeletal survey shows a radial anomaly concerning for possible fracture as well as numerous lytic lesions and periosteal reactions in all long bones (Figs 2 and 3). Laboratory evaluations confirm the diagnosis.The differential diagnosis included NAT, congenital syphilis, multifocal osteomyelitis, late-onset group B streptococcus, malignancy, and Langerhans cell histiocytosis. Syphilis screening resulted positive in the ED. The patient was admitted to the hospital for penicillin therapy. Rapid plasma reagin and cerebrospinal fluid VDRL testing returned positive, confirming congenital syphilis and neurosyphilis. Due to lessened concerns for trauma, further evaluation for NAT was discontinued.Syphilis is a growing public health concern in the United States. During the past decade, congenital syphilis rates have dramatically increased—from historic lows in 2012, with just 9.2 cases per 100,000 live births, to 57.3 cases per 100,000 live births in 2020. This represents a 15% increase since 2019 and a 254% increase since 2016. (2)The rise of syphilis in the United States has been driven by multiple factors. Funding for public health campaigns to combat syphilis has decreased since the 1990s, and the COVID-19 pandemic disrupted already strained public health departments across the country. Approximately 40% of disease infection specialists—public health staff trained in contact tracing, counseling, and ensuring treatment of individuals with sexually transmitted infections—were reassigned to COVID-19 task forces. (3) One-third of these reassignments became permanent, and more than 50% of public health departments discontinued all disease infection specialist fieldwork. (3)(4) These constraints on the ability of public health departments to address sexually transmitted infections have likely contributed to the significant rise in syphilis between 2019 and 2020.Inconsistent prenatal testing guidelines also contribute to missed syphilis diagnoses in pregnant women. The Centers for Disease Control and Prevention (CDC) recommends universal screening in the first and third trimesters and additional screening for high-risk patients at the time of delivery. (2) Even in states where syphilis screening in the first and third trimesters is required by law, adherence to these guidelines is suboptimal, with screening rates ranging from 76.6% to 96% in the first trimester and from 7.8% to 27% in the third trimester. (5)(6) In the case described herein, the patient’s mother had a negative syphilis screen in the first trimester but likely acquired syphilis after the initial screening. The patient likely contracted syphilis in utero rather than after delivery, as he was born via cesarean delivery only 2 hours after rupture of membranes. More frequent prenatal testing, with particular emphasis on testing in the third trimester and at the time of delivery, may have detected maternal syphilis and prevented vertical transmission to the fetus.Although the effect of congenital syphilis on the fetus can be severe, occasionally resulting in stillbirth or hydrops fetalis, 60% to 90% of infants are initially asymptomatic. (7) For these infants, signs of syphilis are most likely to develop within the first 3 months after birth as spirochetes disseminate throughout the body. As seen in this patient, skin lesions, typically desquamating or maculopapular in nature, and rhinitis, or “snuffles,” are common. Syphilis can be transmitted through contact with fluid from cutaneous lesions and nasal discharge, both of which contain live spirochetes. Other symptoms include fever, failure to thrive, and hepatosplenomegaly. Common laboratory findings include hyperbilirubinemia, leukocytosis, anemia, and elevated liver transaminase levels, the latter of which was observed in our patient. Radiologic findings include syphilitic osteomyelitis and osteitis, which can be present in multiple long bones. As demonstrated in our patient, localized bilateral metaphyseal destruction of the medial proximal tibias results in a scalloped appearance of the bone, known as the Wimberger sign, which is pathognomonic for congenital syphilis. (1)Clinicians should be aware of the resurgence of congenital syphilis because its symptoms can mimic other illnesses, including NAT. (8)(9)(10)(11) Although unexplained fractures in premobile infants should appropriately raise consideration of NAT, clinicians should maintain a broad differential diagnosis, inclusive of medical conditions that might mimic traumatic findings. In this case, the ED physicians appropriately consulted the child abuse team due to a possible radial fracture without a history of trauma, although both teams noted that the appearance of the underlying bone was diffusely abnormal and atypical for trauma. Multidisciplinary collaboration revealed that the bony abnormalities were widespread and more suggestive of a systemic process, specifically, congenital syphilis. When the diagnosis was confirmed, the concern for NAT was lessened and a CPS referral for abuse was not indicated. The diminished arm movement was attributed to pseudoparalysis of Parrot, a rare but classic feature of congenital syphilis in which periostitis causes pain and consequently disuse of the affected limb. (12)The involvement of a multidisciplinary team was instrumental in making a timely and accurate diagnosis of congenital syphilis and avoiding a misdiagnosis of abuse. Unfortunately, not all children and families who present with concerns for NAT are treated similarly. It is well documented that socioeconomic status and race/ethnicity influence physicians’ suspicions and initiation of evaluation for NAT. (13)(14)(15)(16) Multiple studies have shown that physicians are more likely to order skeletal surveys and place CPS referrals for patients who are publicly insured, uninsured, or otherwise perceived to be of low socioeconomic status compared with patients with private insurance and/or high socioeconomic status. (14)(15)(16) Black children are also overrepresented in NAT evaluation and CPS reporting, as clinicians are less likely to recognize abuse in white infants and less likely to order appropriate evaluations. (15) Child welfare outcomes also vary by racial group. Black children are more likely to be referred for maltreatment, substantiated as victims, and enter foster care than white children. (17) These differences diminish when adjusting for socioeconomic risk factors, reflecting the role of systemic racism in the unequal distribution of maltreatment risk factors and subsequent disproportionality in the child welfare system. (18)(19) Once involved in the child welfare system, Asian and Black families face disparities in supportive services because they are less likely than white families to receive mental health resources, substance use counseling, and family preservation services. (20)Although some social factors, such as low socioeconomic status, parental substance use, young parental age, and low educational attainment, are associated with maltreatment risk, this information should not drive individual medical evaluations or reporting for abuse. (13)(16) All families should be screened for social determinants of health, as early identification of needs and referral to appropriate resources can help alleviate social stressors that place children at risk for abuse. In our patient’s case, CPS was involved at birth due to maternal substance use and was coordinating substance use treatment for the patient’s mother. Hospital social workers assisted by communicating with CPS and arranging follow-up care. Although physicians may be hesitant to involve social work or child abuse teams in clinical care, standardized early involvement of child abuse experts is associated with reduced bias in CPS reporting. (21)(22)The patient was admitted to the general medicine service and continued treatment with intravenous penicillin. On the evening of admission, he developed a fever to a temperature of 102°F (38.9°C), which was thought to be related either to his active syphilis infection or to a Jarisch-Herxheimer reaction. On hospital day 4, he developed swelling and tenderness of his hands and digits without associated erythema, consistent with syphilitic dactylitis. An ophthalmologic examination found no signs of ocular syphilis but did identify incidental optic nerve hypoplasia, which prompted magnetic resonance imaging of the brain. This imaging was normal. The patient’s inflammatory markers, transaminase levels, dactylitis, and left arm mobility improved throughout hospitalization. After completing 10 days of antibiotic drug therapy, he was discharged with outpatient follow-up with infectious disease, orthopedics, and physical therapy.Congenital syphilis rates have risen dramatically in the past decade. Prenatal testing for syphilis continues to be suboptimal, even in states that legally mandate testing.The symptoms of congenital syphilis can mimic other disease processes, including respiratory illness, malignancy, multifocal infection, and NAT.When considering a diagnosis of NAT, physicians should be aware of the well-documented racial, ethnic, and socioeconomic biases that can inappropriately influence medical decision-making. Patients are more likely to undergo evaluation for abuse and be reported to CPS if they are of low socioeconomic status, publicly insured, or from families of color. (13) Collaboration with a multidisciplinary team including child abuse pediatricians, ED physicians, and pediatric radiologists can be helpful in aiding diagnosis, evaluating for alternative medical explanations, and ensuring objectivity in CPS reporting.