Key Clinical Findings & Highlights
- Identifies midline cutaneous lumbosacral pits as vital early warning signs of underlying occult spinal dysraphism.
- Demonstrates total microsurgical excision of the fistulous tract and conus abscess with zero permanent neurological deficits.
- Highlights the essential role of spinal MRI with Diffusion-Weighted Imaging (DWI) in distinguishing epidermoid abscess from simple cysts.
Abstract
Introduction & Background
Congenital dermal sinus tracts represent focal failures of primary neurulation occurring during the third to fourth gestational weeks. While dermal sinus tracts may be asymptomatic at birth aside from a subtle cutaneous ostium, hyperpigmentation, or hair tuft, their potential to cause catastrophic neuroaxis infections is well documented. Intramedullary epidermoid cysts associated with an infected dermal sinus tract are exceptionally rare, representing less than 1% of all intraspinal abscesses. Prompt diagnosis and definitive microsurgical extirpation are essential to avoid permanent motor deficit, bladder incontinence, or fatal arachnoiditis.
Clinical Case Presentation & Diagnosis
A 4-year-old child presented with progressive low back pain, recurrent high-grade pyrexia, irritability, and progressive motor weakness in both lower limbs over three weeks. Physical examination revealed a tiny cutaneous pinpoint pit in the upper sacral midline surrounded by localized cutaneous erythema. Neurological examination showed bilateral lower extremity paraparesis (motor power 3/5), hyperactive deep tendon reflexes, and bilateral extensor plantar responses. Magnetic resonance imaging (MRI) of the whole spine demonstrated a well-defined T1-hypointense, T2-hyperintense intramedullary cystic lesion expanding the conus medullaris with marked peripheral ring enhancement following intravenous gadolinium administration. A continuous fistulous dermal tract was traced from the skin dimple down to the thecal sac and conus.
Surgical Technique & Management
The patient underwent emergent surgery in the prone position. An elliptical skin incision encompassing the cutaneous dermal sinus ostium was made. Under high-magnification operative microscope, the fibrous sinus tract was meticulously dissected from subcutaneous fat down to the deep lumbar fascia and dura mater. Following midline laminectomy and dural opening, the tract was traced entering the conus medullaris. A gentle dorsal midline myelotomy exposed the thick-walled conus abscess cavity containing purulent, foul debris and desquamated squamous epithelial flakes. Complete evacuation of the abscess contents and excision of the epidermoid cyst wall and sinus tract were achieved with preservation of all normal neurological functional tissue.
Discussion & Literature Context
The coexistence of an infected dermal sinus tract with a conus medullaris epidermoid abscess is an uncommon but grave clinical condition. In our series, early high-resolution MRI with diffusion-weighted imaging (DWI) proved pivotal in differentiating epidermoid contents from typical arachnoid cysts or localized hematomas. Aggressive broad-spectrum intravenous antibiotic coverage combined with complete microsurgical tract resection yields excellent neurological recovery without recurrent tethered cord syndrome.
Conclusion
Any midline cutaneous lumbosacral dimple in pediatric patients warrants diligent neurosurgical evaluation with spinal MRI before infection or irreversible neurological deficits develop. Complete microsurgical resection of the tract and conus abscess cavity allows complete motor and sphincter recovery.
How to Cite This Research
Dr. Surendra K. Gupta, P. Singh, R. K. Gupta, R. Sharma, L. S. Nehete (2021). "Infected congenital lumbosacral dermal sinus tract with conus epidermoid abscess: a rare entity". Child's Nervous System, Volume 37, Issue 3, Pages 741-747.
