Back, Joint, and Extremity Pain - Case 5-5: 13-Year-Old Boy
I. History of Present Illness
A 13-year-old African-American boy without significant past medical history
presented to the emergency department with a 2-day history of worsening back
pain. The pain was located in his upper and lower back, and, although he was
uncomfortable in any position, standing upright made his back pain
significantly worse. His pain was not relieved with cyclobenzaprine, a muscle
relaxant. The patient had no history of trauma and denied weakness, sensory
loss, and bowel or bladder dysfunction as well as recent fevers, upper
respiratory symptoms, cough, nausea, vomiting, weight loss, and night sweats.
II. Past Medical History
His past medical history was remarkable for one previous episode of back pain 2
years earlier that required use of a wheelchair for 2 weeks. He had received
iron supplements for treatment of anemia at that time. Additional details of
that episode were not available. He had never been hospitalized and had no
surgical problems. He was not sexually active and had no history of cigarette
or drug use. Family history was significant for a sister with sickle cell
trait.
III. Physical Examination
T 37.7°C; RR 24/min; HR 110 bpm; BP 105/70 mm Hg; Weight 35kg.
The patient was a well-developed, well-nourished male crying in pain. Head,
eyes, ears, nose, and throat were normal. There was no lymphadenopathy. There
was no thoracic wall tenderness. The heart and lung sounds were normal. His
abdomen was soft and nontender without hepatomegaly or splenomegaly. He had no
point tenderness of his back; however, he complained of
“inside pain” over his sacrum. The rectal examination revealed normal sphincter tone and no
palpable masses. His extremities were warm with good peripheral pulses, and he
had full range of motion of all four extremities.
IV. Diagnostic Studies
Complete blood count revealed 8,400 WBCs/mm3 (81% segmented neutrophils, 17% lymphocytes, 2% basophils, 1% eosinophils, and
no bands); hemoglobin, 10.4 g/dL; MCV, 72fL; mean corpuscular hemoglobin
content (MCHC), 23.4 g/dL; red cell distribution width (RDW), 15.1; platelets
241,000/mm
3; and a reticulocyte count of 3%. Blood smear showed anisocytosis,
poikilocytosis, and polychromasia. Electrolytes, blood urea nitrogen,
creatinine, and glucose were normal. ESR was 20 mm/hour. Urinalysis revealed
small amounts of urobilinogen.
V. Course of Illness
The patient was treated with morphine and ketorolac without much relief. He
became febrile to 38.7
°C, and blood and urine cultures were obtained. The pain became localized to his
sacral/coccygeal region; however, he had no numbness or tingling, and his
reflexes remained normal. Abdominal radiography did not reveal bowel
obstruction; however, it suggested a likely underlying condition (Fig. 5-6)
that was later confirmed by specific testing. An MRI of the lumbosacral spine
was negative for an abscess or a locally infiltrative process.
Discussion: Case 5-5
I. Differential Diagnosis
Back pain is less common in children than in adults, but in children is more
often the result of a serious underlying pathology. In adolescents, traumatic
or overuse injuries such as compression fractures, musculoskeletal strain,
spondylolysis, spondylolisthesis, and lumbar disc herniation should be
considered. Most of these injuries manifest during the adolescent growth spurt
and are associated with repeated lifting and back extension, especially in
sports. Infections of the vertebral column that cause back pain include
osteomyelitis and diskitis especially in toddlers and young children. Less
common but serious causes include spinal epidural, paraspinal, or psoas
abscess; transverse myelitis; and pyomyositis. Urinary tract infections and
pneumonia can cause back pain but are less likely in the absence of urinary or
respiratory symptoms. Neoplastic diseases such as leukemia and lymphoma should
be considered, especially in the presence of progressive, indolent pain.
Malignancies are usually accompanied by constitutional symptoms including
weight loss, fatigue, fever, and loss of appetite. Rare causes of back pain
include spinal hematoma, spinal tuberculosis (Pott
's disease), and brucellosis, a zoonotic infection transmitted from animals to
humans that causes flu-like symptoms including back pain. Back pain secondary
to acute bone infarction often occurs in adolescents with SCD. Patients usually
have normal or mildly elevated temperature and ESR. However, in some cases this
condition is indistinguishable from acute osteomyelitis. SCD should be included
in the differential diagnosis of an African-American child with back pain,
anemia, and a family history of sickle cell trait. In this case, the acute fall
in the patient
's hemoglobin level, splenomegaly, vertebral abnormalities, and the persistence
and severity of the symptoms prompted further evaluation, which led to the
diagnosis. Although most patients are diagnosed by newborn screening tests,
some patients may inadvertently not be screened or may be lost to follow-up.
II. Diagnosis
Biconcave vertebral depressions, known as the “fish-mouth” deformity, suggested the diagnosis of SCD (see Fig. 5-6), a group of conditions
characterized by the presence of hemoglobin S (HbS) in the absence of normal
hemoglobin A (HbA) or in a quantity greater than that of HbA. Hemoglobin
electrophoresis confirmed the diagnosis of sickle
–beta+-thalassemia (Sbeta+): HbA (18.4%), HbS (63%), HbF (8.1%), HbA2 (7.7%). Sbeta+, a less severe form of SCD, results from inheritance of the sickle hemoglobin
(HbS) and beta
+ thalassemia genes. In Sbeta+, some normal beta chains are produced, and therefore some HbA is present. A
similar hemoglobin profile may be seen in homozygous (HbSS) disease after
transfusion; however, in this case, the patient never received a RBC
transfusion.
The diagnosis was a vaso-occlusive event secondary to underlying Sbeta+ thalassemia. In retrospect, the anemia diagnosed during his previous episode of back pain was
probably caused by SCD rather than isolated iron deficiency anemia.
III. Incidence and Epidemiology of Sickle Cell–Beta+ Thalassemia
SCD is an autosomal recessive genetic disorder that is characterized by the
presence of HbS in RBCs. The most common forms of SCD are homozygous SCD
(HbSS), sickle cell
–hemoglobin C disease (HbSC), and two types of sickle cell–beta-thalassemia, Sbeta+ and Sbeta0 (Table 5-4). Individuals who inherit the genes for both HbA and HbS have sickle
cell trait, a generally benign and asymptomatic carrier state.
HbS results from an inherited abnormality of hemoglobin function caused by
substitution of valine for glutamine at the sixth position of the beta-globin
gene. Deoxygenated HbS polymerizes, distorting the shape of the RBC. RBC
distortion leads to hemolysis and vaso-occlusion, the two dominant features of
sickle cell disease. Beta-thalassemia is caused by single point mutations that
result in decreased (beta
+) or absent (beta0) synthesis of beta-globin. This commonly results in microcytic and hypochromic
anemia.
The occurrence of sickle cell–beta-thalassemia is determined by the distribution and prevalence of two
abnormal genes. The HbS gene occurs in high frequency among populations in
equatorial Africa, the Mediterranean area, the Middle East, and India
—populations that were exposed during evolution to selection pressure from
falciparum malaria. The distribution of beta-thalassemia tends to be sporadic,
with high frequencies in the Mediterranean and in southeast Asia. The
combination of beta-thalassemia with the sickle mutation results in the
combined heterozygous condition known as sickle cell
–beta-thalassemia. The clinical problems are quite variable depending on the
amount of HbA produced. Sbeta
0 produces no normal beta-chains and therefore no HbA. Sbeta0 resembles HbSS electrophoretically, hematologically, and clinically. In
contrast, the spectrum of severity in Sbeta
+ varies, ranging from very little HbA production to near-normal amounts,
depending on the particular beta-thalassemia mutation.
IV. Clinical Presentation
Universal screening for SCD has been widely available in most states in the
United States since 1986, and most children with SCD are diagnosed as newborns.
A few infants, even in states with universal screening, may not be screened; in
others, the diagnosis may be missed because of extreme prematurity, blood
transfusions before screening, or inadequate follow-up after discharge. In some
patients with Sbeta
+, the levels of HbA are high enough to impair polymerization of HbS and reduce
intravascular sickling of the RBCs. The early clinical course in these patients
is mild, with significant symptoms appearing later in life.
Acute and chronic complications of SCD involve multiple organ systems (Table
5-5). Bones and joints are major sites of pain in vaso-occlusive events. Acute
bone pain is caused by marrow ischemia, which results in necrosis and
inflammation. Pain is widespread and migratory during the acute painful crisis.
Local tenderness, warmth, swelling, and impaired motion occur with a severe
pain episode as the generalized pain improves. As seen in this patient,
vertebral infarction may lead to collapse of the end-plates, known as
“fish-mouth” vertebrae. No single clinical feature can reliably distinguish osteomyelitis
from bone infarction. Acute painful events are the most common cause of
emergency department visits and hospitalizations among patients with SCD. These
events may be precipitated by weather extremes or temperature changes,
dehydration, infection, stress, or menstruation; however, the majority of
painful events have no identifiable trigger. Painful episodes vary from mild to
debilitating. Pain is usually self-limited, lasting from a few hours to a few
days, although inadequate treatment may prolong the episode for weeks.
V. Diagnostic Approach
Hemoglobin electrophoresis. This is the most popular method used in clinical laboratories to determine
hemoglobin phenotype.
Complete blood count with differential. At baseline in patients with Sbeta+, the hemoglobin values, reticulocyte count, and WBC count are near-normal, with
the major difference being modestly low MCV and MCHC values. This is in
contrast to HbSS disease, in which the steady-state WBC and reticulocyte counts
are higher than in an unaffected person. The WBC count is often elevated with
both bone infarcts and infection; however, a shift in the differential toward
neutrophil predominance is more likely with osteomyelitis than with infarction.
Peripheral blood smear. Microcytosis, hypochromia, anisocytosis, and poikilocytosis characterize Sbeta+. Sickled cells are not always seen, especially if high levels of non-S
hemoglobin are present, making the diagnosis less obvious in some cases.
Blood Cultures. Blood cultures should be obtained before antibiotics are administered. Blood
cultures are negative in bone infarction and frequently are positive in
osteomyelitis.
Sequential radionuclide bone marrow and bone scan. Diminished radionuclide uptake on the bone marrow scan, indicative of decreased
blood flow in the bone marrow, and abnormal uptake on the bone scan at the site
of pain are seen with bone infarction. In contrast, acute osteomyelitis results
in normal activity on bone marrow scans and increased activity on bone scans.
Plain radiography. This is useful in monitoring the progression of established changes of
infection, infarction, and osteomyelitis but not in diagnosing acute infections
or infarctions. In older children and adolescents, plain radiographs may show
deossification due to marrow hyperplasia and flattened, widened vertebral
bodies with biconcave depressions of the end-plates, known as
“H-shaped” or “fish-mouth” vertebrae.
VI. Treatment
Severe bone pain should be considered a medical emergency that prompts timely
and aggressive management until the pain decreases to a tolerable level. Major
barriers to effective management of pain are inadequate assessment of pain and
biases against opioid use. Most of the time, these biases are based on
clinician uncertainty regarding opioid tolerance and physical dependence, and
confusion with addiction.
As previously mentioned, bone infarction resembles osteomyelitis. Fever in cases
of bone infarction is due to necrosis and inflammation associated with marrow
ischemia. Blood cultures must be obtained if empiric antibiotics are initiated.
Appropriate antibiotics should cover
Salmonella spp. and S. aureus, the most common causes of osteomyelitis in children with SCD.
Patients with signs of moderate to severe dehydration should receive 10 to 20
mL/kg of intravenous normal saline, followed by intravenous fluid at or
slightly above (1.0 to 1.5 times) the daily fluid requirement. It is important
to assess the severity of pain at presentation and at frequent intervals, using
age-appropriate pain-measuring scales. Pain should be reevaluated every 15
minutes until pain starts to decrease, then every 30 to 60 minutes as needed.
Severe acute pain requires intravenous medication such as morphine sulfate,
hydrocodone, or fentanyl, with or without NSAIDs such as ketorolac and
ibuprofen. Patient-controlled analgesia (PCA) devices restore patient control
over pain and may be used for patients in severe pain. PCA pumps provide
analgesic medication continuously at a low baseline rate and allow patients to
self-administer an additional dose of opioid whenever they feel a need for more
pain relief. Continuous epidural analgesia has been used in patients with pain
below the 4th thoracic dermatome for whom intravenous PCA opioids and nonopioid
analgesics have failed; however, not much information is available about its
use in patients with SCD.
Patient and parental preferences for pain medication should be considered,
because individual variations in drug metabolism determine the dose-response to
analgesia. The use of parental meperidine should be avoided because of CNS
toxicity related to its metabolite normeperidine. Patients receiving opioids
for longer than 1 or 2 weeks should be weaned slowly over several days to
prevent withdrawal symptoms.
Side effects of opioids, including respiratory depression and sedation, should
be monitored closely. Antiemetics such as Compazine (prochlorperazine) or
metachlorpropamide effectively treat symptoms of opioid-related nausea. Stool
softeners to prevent constipation should be taken daily if patients continue to
take opioids for longer than a few days.
VII. References
1. Benjamin LJ, Dampier CD, Jacox AK, et al. Guidelines for the management of acute and chronic pain in sickle-cell disease. APS Clinical Practice Guidelines Series, No. 1. Glenview, IL: American Pain
Society, 1999.
2. Embury SH, Hebbel RP, Mohandas N, et al., eds. Sickle cell disease: basic principles and clinical practice. New York: Raven, 1994
3. Lane PA. Sickle cell disease. Pediatr Clin North Am 1996;43:639–664.
4. Serjeant GR, Sergeant BE. Sickle cell disease, 2nd ed. Oxford, England: Oxford University Press, 2001.
5. Yaster M, Kost-Byerly S, Maxwell LG. The management of pain in sickle cell
disease.
Pediatr Clin North Am 2000;47:699–710.
Pictures
Book Source Details
- Book Title: Pediatric Complaints and Diagnostic Dilemmas
- Author(s): Samir S Shah MD; Stephen Ludwig MD
- Year of Publication: 2003
- Copyright Details: Pediatric Complaints and Diagnostic Dilemmas, Copyright © 2003 Lippincott Williams & Wilkins.
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Copyright Details: Pediatric Complaints and Diagnostic Dilemmas, Copyright © 2008 Williams & Wilkins.
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