Case Presentation: A 67-year-old woman with a history of cocaine use presented with six weeks of progressive bilateral upper and lower extremity weakness, burning pain, and difficulty ambulating. Exam was significant for low grade fever and decreased sensation to pinprick in a stocking-glove distribution in all extremities. Muscle strength was reduced in the distal upper and lower extremities (0/5 distal feet, 3/5 bilateral quadriceps, 4/5 proximal lower extremities, 3/5 hands) and muscle atrophy was noted as well. The right patellar reflex and bilateral Achilles reflexes were absent bilaterally. Labs were significant for a progressive AKI over four weeks (Cr 1.46 mg/dL; baseline 0.6 mg/dL) and leukocytosis of 16 k/uL. ESR was elevated to 114 mm/h and CRP to 22.6 mg/dL. Urine studies were notable for 1.5 g proteinuria and 3+ blood. Urine toxicology was positive for cocaine. Serologic workup showed high titer positive anti-MPO and low titer positive anti-PR3. A diagnosis of ANCA vasculitis was confirmed with kidney biopsy.
Discussion: While peripheral neuropathy is a common cause of chronic pain, an acute presentation raises concern for a reversible process. Detailed history and thorough neurologic exam revealed that this patient had a subacute progressive presentation of neuropathy. Identifying the red flags related to substance use, symptom timing, and connecting it to renal dysfunction and elevated inflammatory markers, is crucial to trigger the workup for ANCA vasculitis.Cocaine-induced vasculitis is not a common cause of neuropathy. However, clinical suspicion should be high, particularly in areas with high rates of cocaine use. While the exact pathophysiology is unclear, case reports have identified levamisole, an additive meant to “cut” cocaine, as a causative agent. Levamisole associated vasculitis typically causes a “dual positivity” of MPO and PR3 which is seen in this case. Case studies describe the presenting symptoms as arthralgias (83%), gangrenous skin lesions (61%) and constitutional symptoms (72%). These develop along an acute-subacute time course ranging from 3-36 weeks. Peripheral neuropathy is less commonly reported, and if present, is less severe relative to the symptoms described above. However, this case is atypical in that neuropathy is the primary symptom while skin and joint symptoms were absent.A pitfall in the early presentation of this case was the attribution of AKI to pre-renal etiologies as opposed to an intrinsic process. Considering that 70% of community acquired presentations of AKI are due to an acute pre-renal etiology, a bias exists towards that diagnosis. The chronicity of renal dysfunction shows that this was also a progressive subacute process. Furthermore, initial urinalysis showed significant proteinuria and hematuria which raised suspicion for an intrinsic process rather than simply a pre-renal AKI. Finally, placing renal dysfunction in the context of leukocytosis, elevated inflammatory markers and neuropathy raises suspicion for a unifying process such as vasculitis. This highlights the importance of contextualization to prevent premature closure in the assessment of AKI.
Conclusions: Patients presenting with acute to subacute polyneuropathy and cocaine use, in the presence of other systemic manifestations, should be evaluated for levamisole induced ANCA vasculitis. Early identification of this acute inflammatory process can in turn lead to early initiation of immunomodulatory therapies and improved disease outcomes.