Calcium pyrophosphate dihydrate crystal deposition disease and MRSA septic arthritis of the atlantoaxial joint in a patient with Tourette syndrome

Abstract

A 45-year-old male patient with Tourette syndrome presented to the emergency department with worsening neck pain and stiffness of 1-week duration. Associated symptoms included headache, hoarse voice, trismus and odynophagia. The patient was haemodynamically stable without fevers or leucocytosis. He exhibited cervical spinal and paraspinal tenderness with very limited range of motion. Erythrocyte sedimentation rate and C reactive protein were elevated, and blood cultures grew methicillin-resistant Staphylococcus aureus (MRSA). Lumbar puncture was unremarkable. CT and MRI of the neck showed calcification of the longus colli, fluid and capsular distention of C1–C2 joints, enhancement of the joint capsule and retropharyngeal oedema suggestive of septic arthritis. Fluid was aspirated from C1 to C2 joint by interventional radiology and showed calcium pyrophosphate crystals and heavy MRSA colonisation, consistent with both pseudogout and septic arthritis of the cervical vertebrae. The patient was started on a 6-week course of daptomycin and showed gradual improvements in neck pain and mobility.

Background

Neck pain is a common emergency room complaint. Aetiology can range from benign musculoskeletal strain to more severe conditions that must be excluded, such as meningitis, epiglottitis, fracture, discitis, neoplastic processes or vertebral infections. In the evaluation of acute joint pain, the typical diagnoses to consider first are septic arthritis and crystal deposition diseases, like gout or pseudogout. Differentiating the two clinically can be difficult as both classically present with joint pain, warmth and swelling in a febrile patient, but definitive diagnosis can be made by arthrocentesis and synovial fluid studies.¹ While these pathologies are rare in the cervical spine, it is critical to rule out such destructive conditions before they progress to irreversible deformity and disability; this is particularly true when both infectious and crystalline arthropathy are concomitantly at play because the latter has been known to delay the identification and treatment of septic arthritis.²

Case presentation

A 45-year-old Caucasian man with history of lumbosacral degenerative joint disease, obstructive sleep apnoea (OSA) and Tourette syndrome with motor tics of the neck presented to the emergency department with constant, worsening neck pain and stiffness of 1-week duration. The patient had had no significant relief with Tylenol, heat, ice, non-steroidal anti-inflammatory drugs (NSAIDs) or muscle relaxers prescribed by his primary care physician. The patient also had a generalised headache, odynophagia, trismus and hoarseness of voice that had progressed since the posterior, bilateral neck pain began. The patient remained afebrile with day of admission vitals showing blood pressure of 146/91, pulse of 79, temperature at 37°C, respiratory rate of 14, body mass index of 27.3 kg/m² and oxygen saturation at 92% on ambient air. Physical examination was significant for: limited neck flexion, extension, lateral rotation and lateral flexion bilaterally; tenderness to palpation over cervical spinous processes and paraspinal muscles; and no focal neurological deficits with normal strength, sensation to light touch and reflexes.

Investigations

A CT of the neck identified soft-tissue thickening of the supraglottic airway, as well as bilateral calcifications of the longus colli with prevertebral thickening and oedema extending from C1 to C6, suggesting a provisional diagnosis of calcific tendinitis of the longus colli muscles (figure 1). Otolaryngology consult revealed normal fiberoptic laryngoscopy and an unremarkable ear, nose, throat (ENT) examination. The patient had some improvement in neck pain and mobility with opiates, muscle relaxers and intravenous dexamethasone, and was discharged home the following day.

Figure 1.

(A) CT soft-tissue neck with contrast, sagittal; blue arrow showing calcification of longus colli muscle at C1–C2, suggestive of calcific tendinitis. (B) CT soft-tissue neck with contrast, axial; blue arrows showing bilateral calcification of longus colli, red circle around right-sided retrovertebral fluid at C1–C2.

He returned on the next day in a neck brace with worsened neck pain. A CT angiogram (CTA) of the head and neck was taken which demonstrated new joint effusions of C2–C3 facet joints and calcifications of the transverse ligament with erosions involving the odontoid process (figure 2). A rapid strep test and throat culture were negative. Further laboratory testing showed a normal haemogram with no leucocytosis (white cell count [WCC] ranging from 5.25 to 9.08×10⁹/L). The patient had normal levels of lactic acid (1.0 mmol/L), but elevated erythrocyte sedimentation rate (ESR) (77 mm/hours) and C reactive protein (CRP) (16.90 mg/dL). Viral serologies were negative for antibodies to West Nile virus, hepatitis C and herpes simplex virus (HSV) type 2, but positive for antibodies to HSV type 1. HIV-1/2 antigens and antibodies were also negative. Antinuclear antibody screen and citric citrullinated peptide (CCP) antibodies were negative.

Figure 2.

CT angiogram head and neck, axial; yellow circle highlighting erosions of the odontoid process, blue arrow showing retro-odontoid calcification of the transverse ligament.

A lumbar puncture was performed which revealed normal-range glucose, protein, lactic acid and cell counts, with negative virology testing of the CSF. An MRI of the cervical spine highlighted fluid and capsular distention of C1–C2 joints, enhancement of the joint capsule and retropharyngeal oedema suggestive of septic arthritis (figure 3). The initial blood cultures drawn from the day after his second admission grew methicillin-resistant Staphylococcus aureus (MRSA) in 2/2 bottles at 18 and 35 hours. Subsequently, the C1–C2 joint was aspirated and cultured, also yielding heavy MRSA as well as calcium pyrophosphate dihydrate crystals. Transoesophageal echocardiogram showed normal left ventricular function, no significant valvular abnormalities and no vegetations.

Figure 3.

(A) MRI cervical spine with contrast, T2 sagittal; red circle around retrovertebral fluid with distension of joint capsule at C1–C2 due to septic arthritis. (B) MRI cervical spine with contrast, T2 axial: red circle around right-sided retrovertebral fluid with distension of joint capsule at C1–C2. (C) MRI cervical spine with contrast, T2 sagittal; yellow arrows showing retropharyngeal oedema from C2–C5.

Differential diagnosis

The initial diagnosis for this patient was unspecified cervical dystonia without establishing a clear underlying cause. Initial CT imaging showed no signs of vertebral fracture, subluxation or other obvious bony deformity, but revealed calcific tendinitis, also called basic calcium phosphate (BCP) crystal-associated calcific periarthritis, of the longus colli muscles.³ The ENT consultation and unremarkable laryngoscopy effectively ruled out diagnoses like retropharyngeal abscess, peritonsillar abscess and epiglottitis. A normal lumbar puncture and cerebrospinal fluid (CSF) cultures established no signs of meningitis or encephalitis. Musculoskeletal strain, a diagnosis of exclusion, seemed unlikely given the unrelenting nature of this patient’s pain and worsening clinical state. Similarly, the subacute nature of this patient’s neck disability and associated symptoms, as well as lack of improvement from steroids and NSAIDs, lowered rheumatoid arthritis on the differential. Furthermore, the patient had normal-range anti-CCP antibodies, although this only has a sensitivity of 67% in rheumatoid arthritis.⁴ The final diagnosis was made by blood cultures and aspiration of C1–C2 joint space, both of which grew MRSA, with the latter sample also containing calcium pyrophosphate dihydrate crystals. The presence of these crystals is diagnostic for calcium pyrophosphate deposition disease (CPPD), also called pseudogout. This diagnosis was also supported by the odontoid erosions and calcification of the transverse ligament visualised on CTA of the neck, both of which are characteristic of CPPD.⁵ Ultimately, this patient was established to have cervical dystonia secondary to both CPPD and MRSA septic arthritis of the atlantoaxial joint with concomitant BCP-associated calcific periarthritis and MRSA bacteraemia.

Treatment

The patient was initially given intravenous vancomycin and levofloxacin, which were later transitioned to daptomycin due to vertebral joint aspirate and blood culture susceptibilities.

Outcome and follow-up

The patient’s neck pain and mobility improved on daptomycin and naproxen over the course of his 8-day hospitalisation. After blood cultures were no longer positive, he was discharged home with a peripherally inserted central catheter for a 6-week course of intravenous antibiotics with weekly complete blood count, comprehensive metabolic panel, CRP and creatine phosphokinase levels checked. He has had a return to baseline function with minimal pain, but he continues to undergo physical therapy and receive trigger point trapezius muscle injections for tightness.

Discussion

From the time of admission, this patient exhibited an atypical presentation for his underlying pathology. The patient arrived in moderate distress due to acute neck pain and stiffness, but he was afebrile and overall non-toxic appearing despite the occult presence of both septic arthritis and bacteraemia from MRSA. He had transient tachycardia within the emergency department, but throughout the rest of his hospitalisation he met 0 out of 4 Systemic Inflammatory Response Syndrome (SIRS) criteria (fever or hypothermia, tachycardia, tachypnoea and increased or decreased leucocyte count). The patient intermittently had low-normal pulse oximetry readings ranging from 92% to 98% on room air. While the occasional relatively low arterial oxygen saturation may have been an early indication of sepsis, it may also be explained by the ongoing use of narcotic pain medications and his history of OSA. Another case of atlantoaxial septic facet arthritis, which is extremely rare, has been reported in which the patient had normal inflammatory markers (ESR, CRP, WCC) and lacked a fever.⁶ Cases such as these highlight the importance of keeping infectious aetiologies of neck pain within the differential diagnosis, even in the absence of classic signs.

Risk factors for septic arthritis and staphylococcal bacteraemia include indwelling lines and catheters, skin and soft-tissue infection, prosthetic valves and joints, underlying joint damage, age greater than 80, immunosuppressive conditions or medications, diabetes, alcoholism, or intravenous drug use. It was alarming that this patient was relatively young and had virtually no usual risk factors for septic arthritis or S. aureus bacteraemia. The patient also had a negative HIV-1/2 screen, normal WCC and differential, and no history of recurrent infections, failure to thrive in childhood or opportunistic infections to suggest any inherited or acquired immunodeficiencies. He did, however, have Tourette syndrome with motor tics that involve ‘hitting and whipping his neck’. We propose that chronic microtrauma from his Tourette syndrome could have created a nidus for infection and may have been a predisposing factor to the development of crystal deposition disease in that vertebral joint. Likewise, inflammatory changes from the crystalline arthropathy could have facilitated infection in the vertebral joints. A relationship between Tourette syndrome and joint disease has been studied in children with motor tics who had higher incidences of bone fractures.⁷ In another case, violent neck tics in a patient with Tourette syndrome were suspected to be the underlying cause of a vertebral artery dissection.⁸ Regarding how this otherwise healthy patient developed MRSA infection, he had spent several days chiselling tile out of a room in his house prior to the onset of pain, which may have involved unnoticeable skin penetration from contaminated debris.

In the assessment of acute neck pain, the typical infections to consider are meningitis and soft-tissue infections, as opposed to septic arthritis which is relatively rare in the vertebrae. Pyogenic infections of the cervical spine are the least common site within the axial spine, and exceedingly rare within C1–C2 joints.⁹ Calcium pyrophosphate dihydrate crystal deposition disease or pseudogout is characterised by deposition of CPPD crystals in hyaline cartilage and fibrocartilage. Like septic arthritis, pseudogout of the cervical vertebral joints would present with acute posterior neck pain, fever and neck stiffness, making differentiating the two fairly difficult without joint aspiration.¹⁰ One retrospective study from 2013 identified the prevalence of crystal disease in joint fluid of patients with previously diagnosed arthritis of those joints. They concluded that crystals, particularly CPP crystals, were detected more frequently in patients with pre-existing rheumatoid arthritis, osteoarthritis and even septic arthritis, although there were only three reported cases of concurrent pseudogout and septic arthritis and they do not clarify in which joint space these occurred.¹¹

While there is increasing literature on CPPD within the cervical spine,^12–14 the presence of crystalline arthropathy and septic arthritis within the atlantoaxial joint simultaneously have not been reported in the English literature to this author’s knowledge.

Learning points.

• Infectious aetiologies of joint pain, especially in small joints such as vertebral facets, should not necessarily be excluded in the absence of fever, inflammatory markers or other SIRS criteria.

• Tourette syndrome with chronic motor tics may contribute to or serve as a risk factor for arthropathy and degenerative joint changes.

• Septic arthritis of the cervical vertebral joints is itself a rare process, and very few cases have been reported specifically in the C1–C2 atlantoaxial joint.

• The combination of this methicillin-resistant Staphylococcus aureus septic arthritis and calcium pyrophosphate dihydrate deposition disease in the atlantoaxial joint due to injury from Tourette syndrome tics may be a unique presentation of acute neck pain in the literature.

• The identification of crystalline arthropathy should not thwart further diagnostic evaluation for infection within that particular joint.