The development of novel therapeutics in neuro-oncology faces significant challenges, often marked by high costs and low success rates. Despite advances in molecular biology and genomics, targeted therapies have had limited impact on improving patient outcomes in brain tumors, particularly gliomas, due to the complex, multigenic nature of these malignancies. While significant efforts have been made to design drugs that target specific signaling pathways and genetic mutations, the clinical success of these rational approaches remains sparse. This review critically examines the landscape of neuro-oncology drug discovery, highlighting instances where serendipity has led to significant breakthroughs, such as the unexpected efficacy of repurposed drugs and off-target effects that proved beneficial. By exploring historical and contemporary cases, we underscore the role of chance in the discovery of impactful therapies, arguing that embracing serendipity alongside rational drug design may enhance future success in neuro-oncology drug development.

Elsberg syndrome is a rare infectious neurologic condition characterized by acute or subacute lumbosacral radiculitis, with or without associated myelitis, most commonly linked to herpes simplex virus type 2 (HSV-2) or varicella zoster virus (VZV). Patients present with cauda equina-like symptoms, including urinary retention, saddle anesthesia, and neuropathic pain. Due to its variable diagnostic findings, the condition is often underrecognized. We present the case of a 32-year-old woman with no prior neurologic history who developed progressive urinary retention, saddle anesthesia, genital sensory loss, and neuropathic pain following a primary genital HSV-2 infection. Initial magnetic resonance imaging of the thoracic and lumbar spine demonstrated no compressive lesion or abnormal enhancement. Cerebrospinal fluid analysis revealed a lymphocytic pleocytosis, though viral polymerase chain reaction testing was negative. Despite nondiagnostic imaging and laboratory findings, the clinical course was most consistent with HSV-associated lumbosacral radiculomyelitis (Elsberg syndrome). The patient was treated empirically with intravenous acyclovir and high-dose corticosteroids, resulting in gradual improvement in bladder function and neurologic symptoms, though residual sensory deficits persisted. Approximately one year later, the patient presented with recurrent sacral pain, constipation, and concern for incomplete bladder emptying after the interruption of antiviral therapy. Repeat imaging again showed no evidence of cauda equina compression, and cerebrospinal fluid analysis demonstrated minimal inflammatory changes. Given her prior history, recurrent Elsberg syndrome was suspected. Symptoms improved rapidly following the re-initiation of antiviral therapy in combination with corticosteroids. This case illustrates the variable and relapsing clinical course of Elsberg syndrome and highlights the importance of maintaining clinical suspicion in patients presenting with acute urinary retention and radicular symptoms following HSV infection, even in the absence of confirmatory imaging or cerebrospinal fluid findings. Early antiviral therapy and close longitudinal follow-up may be important in improving patient outcomes and preventing recurrence.