Acute urinary retention and constipation caused by multi-dermatomal herpes zoster in an immunosuppressed patient

Herpes zoster (HZ, shingles) is the result of the reactivation of latent varicella zoster virus (VZV) within the dorsal root ganglia. It most commonly manifests as a painful, vesicular eruption confined to a single dermatome.1 We report on the case of an immunosuppressed patient with multi-dermatomal, lumbar HZ presenting with the rare complication of acute urinary retention and constipation. A 71-year old female with a background of rheumatoid arthritis treated with methotrexate, leflunomide, upadacitinib (JAK-inhibitor), and long term steroid therapy presented with a 10-day history of unilateral, painful, vesicular rash in the L1–L4 dermatomes (Figs. 1–2) associated with mild fever. Prior to admission, she had been taking simple analgesia and oral aciclovir. Her CRP was elevated at 200 and she was treated as HZ with a superadded bacterial cellulitis with regular analgesia, flucloxacillin and intravenous aciclovir. She reported difficulties with micturition in the 24 h prior to admission and a bladder scan confirmed a residual urine volume of 700 mL. A urinary catheter was inserted with good effect and urine culture was negative. She also reported constipation for the past 3 days. This responded to regular laxatives and phosphate enemas and eased after a few days. Once her neuralgia improved, she was discharged with a temporary catheter for 3 weeks. Follow-up in the urology clinic a month later showed full recovery of bladder function. HZ is caused by reactivation of the varicella zoster virus and those older than 60 years are at much higher risk due to waning cell mediated immunity as one gets older.2 Immunosuppression is also a risk factor and it is a common side effect of JAK inhibitors.3 Lumbar and sacral involvement accounts for 8% and 4% of all HZ cases respectively.4 Most reported cases of HZ-associated bladder and bowel dysfunction involves the sacral dermatomes. Pathophysiology in these cases includes involvement of the sacral parasympathetic fibres, resulting in detrusor areflexia, reduced colonic peristalsis and anal sphincter dysfunction.1,2 Reports of lumbar HZ associated urinary and bowel problems as in our case are rare and relevant aetiology is less clear. Possible mechanisms include involvement of the lumbar sympathetic nerve fibres, which play an important role in regulating micturition and colonic motility.5,6 Urinary retention typically occurs at the time of rash eruption or 1 week later. Voiding function can take 4–6 weeks to recover and removal of urinary catheter should not take place until the infection has completely resolved.7 Although prognosis is usually excellent with complete recovery of bladder and bowel function following conservative management, more severe complications including bladder rupture and colonic pseudo-obstruction have been reported although exceedingly rare.8,9 HZ is not always a purely cutaneous eruption, and in the lumbosacral region it is important for the clinician to be aware of the potential urological and gastrointestinal complications especially in the elderly and immunosuppressed patients. Prompt recognition and treatment will improve prognosis and prevent more severe complications such as organ rupture.