The clinical significance of sacral zoster lies in anatomy. The sacral nerve roots, particularly S2 through S4, carry both autonomic and somatic fibers that govern the bladder, bowel, and genital region. When the reactivated virus inflames these roots, the consequences extend well beyond skin and pain. Patients can develop urinary retention, incomplete bladder emptying, constipation, erectile dysfunction, and, in rare severe instances, sacral radiculomyelitis or Elsberg syndrome, a condition in which inflammation spreads to the conus medullaris and cauda equina. The case report, authored by Aida Farmani and colleagues at Isfahan University of Medical Sciences, documents how the virus’s predilection for dorsal root ganglia translates into dysfunction of organs that seem, on the surface, unrelated to a dermatomal rash.

In this patient’s case, the diagnostic pathway illustrates both the challenge and the solution. Her urinalysis showed no pyuria and her urine culture remained sterile, ruling out the urinary tract infection her dysuria might otherwise have suggested. A Tzanck smear revealed herpetic cytopathic effects, including the characteristic multinucleated giant cells that signal infection with a herpesvirus. But because herpes simplex virus can produce an identical smear picture, particularly in the genital and perineal region, the team turned to polymerase chain reaction testing on a vesicular swab. PCR is considered the diagnostic gold standard, especially in atypical or site-specific presentations like sacral zoster, because it definitively distinguishes varicella-zoster virus from herpes simplex virus, a distinction with very different implications for counseling, treatment, and prognosis.

Treatment began on the day of dermatological evaluation, roughly five days after symptom onset. The patient received oral valacyclovir at 1000 milligrams three times daily for seven days, along with gabapentin titrated for neuropathic pain. No urinary catheterization was necessary because her residual urine volumes remained low and she never developed severe retention. The clinical course was favorable: urinary symptoms resolved completely within two weeks, the skin lesions crusted and epithelialized by three weeks, and at three-month follow-up she reported only mild intermittent neuropathic dysesthesia. This relatively benign trajectory, the authors note, contrasts with some previously documented cases in which bladder dysfunction persisted for months or became permanent.

The pathophysiology of urinary dysfunction in sacral zoster is multifactorial but centers on inflammatory neuritis. The S2 through S4 nerve roots provide parasympathetic innervation to the detrusor muscle, the smooth muscle responsible for contracting the bladder during emptying. Demyelination and inflammation of these fibers can produce detrusor areflexia or hypocontractility, leaving the bladder unable to generate adequate pressure. The result is urinary retention, incomplete emptying, or dysuria. In more extensive infections, the virus can ascend to involve the spinal cord itself, producing radiculomyelitis. Urodynamic studies in previously reported patients have documented hypotonic detrusor function and bladder areflexia, confirming that the neurological injury is real and measurable, not merely subjective.

One of the most treacherous features of sacral zoster is its tendency to announce itself through visceral symptoms before any rash appears. The literature reviewed by the authors includes multiple patients whose first and dominant complaint was acute urinary retention or voiding difficulty, with vesicular eruptions emerging only days later. In such presentations, patients are easily misdiagnosed with urinary tract infection, prostatitis, vulvovaginitis, or other pelvic pathology, delaying antiviral therapy precisely during the window when it is most effective. The authors urge clinicians to consider varicella-zoster virus in any patient presenting with acute urinary symptoms accompanied by dermatomal pain, paresthesia, or perineal discomfort, even when the skin appears entirely normal.

The case report includes a comprehensive table summarizing previously published cases, and the patterns are instructive. Richmond’s classic 1974 series described a 74-year-old woman with S3 zoster and urinary retention who required catheter drainage for thirteen weeks before spontaneous voiding returned. Erol and colleagues reported a 41-year-old man with S2 through S5 involvement who suffered urinary retention, erectile dysfunction, anorectal dysfunction, and even VZV meningitis, though most deficits improved within two weeks of parenteral acyclovir. Seo and colleagues documented an 80-year-old man whose urodynamic testing revealed detrusor areflexia, while Biglione and colleagues reported a 75-year-old man who, at eight-week follow-up, still showed hypotonic neurogenic bladder on urodynamics and required ongoing alpha-blocker therapy for autonomic nerve damage. Across the collected cases, S2 through S4 involvement dominated, urinary retention and voiding dysfunction were the most common urological manifestations, and constipation, dysuria, and sexual dysfunction appeared repeatedly.

Management principles emerging from the accumulated literature are relatively consistent. Early antiviral therapy is critical to limit viral replication, reduce disease severity, and potentially decrease neurological complications. Oral acyclovir or valacyclovir suffices for uncomplicated cases, while intravenous acyclovir is reserved for severe neurological involvement, suspected radiculomyelitis, or significant urinary retention. Adjunctive gabapentin is commonly needed for neuropathic pain. From the urological side, acute retention demands prompt bladder decompression to prevent overdistension injury, alpha-blockers such as tamsulosin have been used to facilitate voiding, and bowel dysfunction may require laxatives or stool softeners. Persistent urinary dysfunction warrants urological follow-up and urodynamic assessment to guide long-term management. Most cases of urinary dysfunction resolve within several weeks, but delayed diagnosis, older age, and extensive neurological involvement are associated with poorer recovery.

The broader lesson of this case extends to vaccination and public health. The patient had no history of varicella or herpes zoster vaccination and no known immunosuppression, underscoring that sacral zoster can occur in otherwise healthy, middle-aged adults. As shingles vaccines reduce the overall incidence of zoster, atypical presentations like this one will become rarer but no less important to recognize, since the diagnostic delay they cause is precisely what allows complications to take root. For dermatologists, urologists, and primary care clinicians alike, the message is straightforward: unexplained acute urinary symptoms paired with unilateral sacral or perineal pain should trigger consideration of varicella-zoster reactivation, careful skin inspection of the S2 through S4 dermatomes, and a low threshold for PCR confirmation. Early recognition, the authors conclude, combined with prompt antiviral treatment and appropriate supportive care, offers the best chance of preventing the prolonged neurological complications that transform a self-limiting rash into lasting disability.

Subject of Research: Sacral herpes zoster presenting with urinary symptoms

Article Title: Isolated Sacral Herpes Zoster With Urinary Symptoms: A Case Report and a Brief Review of the Literature

Article References: Farmani, A., Seyedyousefi, S., & Saber, M. (2026). Isolated Sacral Herpes Zoster With Urinary Symptoms: A Case Report and a Brief Review of the Literature. Clinical Case Reports, 14(10), Article e73684. https://doi.org/10.1002/ccr3.73684

Image Credits: AI Generated

DOI: 10.1002/ccr3.73684

Keywords: herpes zoster, varicella-zoster virus, sacral dermatome, urinary retention, neurogenic bladder, valacyclovir, PCR diagnosis, Elsberg syndrome, detrusor areflexia, postherpetic neuralgia, shingles, case report

The authors, Yongqi Zhang, Eric M. Yeatman and Ranan Dasgupta, frame the problem in terms of the two fundamentally different failure modes of the lower urinary tract. In detrusor underactivity, the bladder cannot contract strongly enough to void, so mechanical assistance is needed during emptying. In detrusor overactivity, by contrast, the bladder contracts aberrantly during the storage phase, producing urgency and incontinence, so the therapeutic goal is inhibition rather than assistance. A single soft-robotic construct, they argue, could in principle address both phenotypes — but only if its control logic is matched to the underlying physiology, and only if a series of formidable biomechanical and regulatory challenges can be overcome.

The core of the proposal is a soft actuator sleeve that conforms to the exterior of the bladder. Unlike traditional rigid implants, which create stress concentrations and can damage delicate tissue, soft actuators made from elastomers, pneumatics or magnetic materials distribute forces gently across the organ wall. The conceptual architecture involves sensing bladder volume and pressure in real time, deciding when assistance is appropriate, and then applying controlled compression to raise intravesical pressure and drive urine through the urethra. The authors describe an idealized pressure–flow relationship for voiding assistance, drawing on Laplace-law insights from ultrasound urodynamics: because wall tension depends on both pressure and radius, a compliant sleeve can amplify the effectiveness of modest actuation forces as the bladder empties and shrinks.

Crucially, the authors insist that voiding assistance must be strictly patient initiated — a human-in-the-loop control philosophy. Micturition is not merely a mechanical reflex; it is gated by supraspinal brain circuits that integrate social context, and functional brain imaging has shown that urgency and continence involve forebrain influences on the pontine micturition switch. An implant that squeezed the bladder autonomously whenever it detected fullness would override this behavioural gating and could cause socially catastrophic emptying. Preserving social continence therefore requires that the machine act only when the patient commands it, with the algorithm serving as an amplifier of intent rather than a replacement for it. Emerging brain–computer interface work decoding urination motor attempts in spinal cord injury patients suggests that even severely injured patients may retain the neural signals needed to trigger such systems.

The opposite phenotype demands the mirror-image strategy. For detrusor overactivity, the authors propose autonomous, closed-loop neuromodulation that detects and inhibits aberrant bladder micromotions during storage without any conscious patient intervention. Unregulated autonomous micromotions of the bladder wall have been implicated in both overactive bladder and detrusor underactivity, and animal studies have demonstrated that closed-loop stimulation triggered by the frequency spectrum of non-voiding bladder activity can suppress unwanted contractions. Recent advances in precise tibial nerve stimulation, guided by evoked compound action potential feedback, point toward implantable systems that could continuously monitor bladder electrical or mechanical signals and deliver inhibitory neuromodulation the moment pathological activity begins — a genuinely artificial continence reflex.

Three families of actuators are emerging as candidates for the mechanical side of the problem, each at a different level of technology readiness. Pneumatic artificial muscles, including PneuNet-type bending actuators, offer high forces and simple fabrication but require pneumatic lines or pumps that complicate implantation. Dielectric elastomer actuators, which squeeze a soft elastomer film between compliant electrodes at high voltage, deliver large strains and fast response, and recent multilayer designs have achieved impressive performance — yet they face dielectric breakdown risks and the challenge of generating kilovolt-level fields safely inside the body. Magnetic soft actuators, in which embedded magnetic particles allow an implant to be deformed by external fields, have already been used to build a magnetically controlled robotic bladder that enhanced urine flow in experimental work, and they eliminate the need for on-board power electronics at the cost of requiring an external field source.

Whatever the actuator technology, the authors identify a set of biomechanical constraints that any clinical system must solve. During the filling phase, a snugly fitted sleeve can create a suction effect that resists bladder expansion, so the design must incorporate fail-safe open mechanical architectures that relax passively as the organ fills. Long-term implantation inevitably provokes fibrotic encapsulation, the foreign-body response that thickens tissue interfaces and degrades both sensing fidelity and mechanical coupling. Power delivery is equally thorny: implantable batteries add volume and eventually require replacement, driving interest in wireless approaches ranging from ultra-low-frequency magnetic energy focusing to ultrasound and magnetoelectric transduction. Encapsulation films built on atomic-layer-deposited nanolaminates must keep body fluids out for years, and any magnetic components must satisfy MRI safety standards such as ISO/TS 10974 and the relevant ASTM test methods for heating, torque and displacement.

Sensing and computation, meanwhile, are advancing rapidly on the soft-electronics front. Fully implantable, sensorized artificial bladders have been demonstrated that monitor volume and fullness continuously, and wireless bioelectronic harnesses with soft strain sensors can track bladder function through surgical recovery. Stretchable sensors based on liquid metals, graphene, conductive hydrogels and high-linearity capacitive designs provide the raw signals, while in-sensor and near-sensor computing — the emerging discipline of tiny machine learning — allows classification of bladder states on milliwatt-scale edge processors rather than in the cloud. The authors point to benchmark suites such as MLPerf Tiny as evidence that the computational hardware needed for on-board, adaptive control is arriving just as the actuator hardware matures.

The final hurdles are ethical and regulatory rather than purely technical. Algorithmic continence control raises questions about autonomy, consent and failure modes: what happens when an adaptive machine learning system drifts, or is compromised? The authors note that regulatory pathways for adaptive artificial intelligence in bioelectronics are still being created — the US Food and Drug Administration has only recently finalized guidance on predetermined change control plans for AI-enabled device software and on cybersecurity in medical devices — and that a definitive roadmap must outline how continuously learning implants will be validated, updated and monitored over a lifetime of use. Sterilization standards, biocompatibility evaluation under ISO 10993 and radio-spectrum rules for medical implants further shape the engineering envelope.

None of these obstacles, the authors conclude, is fatal; each is the kind of problem that interdisciplinary collaboration between engineers, urologists and neuroscientists has solved before in adjacent fields, most visibly in soft robotic cardiac sleeves that restored pumping function in experimental hearts. If the field can integrate fail-safe mechanics, robust sensing, patient-centred control and trustworthy adaptive algorithms, soft-robotic bladder orthoses could transform the management of lower urinary tract dysfunction — replacing the catheter bag with an invisible, compliant machine that restores not just voiding, but the quiet, unremarkable social confidence that continence makes possible. For a condition that has seen so little therapeutic progress over the past few decades, that would be nothing short of revolutionary.

Subject of Research: Soft robotic bladder implants for restoring urinary voiding and continence control

Article Title: The potential of soft robotics for the restoration of urinary voiding

Article References: Zhang, Y., Yeatman, E. M., & Dasgupta, R. (2026). The potential of soft robotics for the restoration of urinary voiding. Nature Reviews Urology. https://doi.org/10.1038/s41585-026-01186-z

Image Credits: AI Generated

DOI: 10.1038/s41585-026-01186-z

Keywords: soft robotics, bladder, urinary retention, detrusor underactivity, detrusor overactivity, neuromodulation, bioelectronics, implantable devices, continence, dielectric elastomer actuators, closed-loop control, urology