Split cord malformations (SCMs) are uncommon congenital anomalies that are usually detected in children, but can present in adulthood with signs and symptoms of spinal cord tethering. SCMs rarely occur in association with a lipoma and a defect in the posterior elements. A 37-year-old man presented with 6 months of new-onset leg weakness, urinary urgency, and reduced sensation in his feet. He developed pain radiating from his low back into his legs, worsened by bending forward and walking. Prior to this presentation, he had not noticed any symptoms. MRI revealed a congenital fusion from L2 to L4 with a type I SCM and a lipoma extending through a dorsal bony defect and terminating at the duplicated spinal cord. A posterior L2-4 lumbar laminectomy was performed to excise the bony spur, resect the spinal cord lipoma, and section the fatty filum terminale. Removal of the bony or fibrous septum and intradural lipoma and sectioning of the fatty filum terminale are required for effective detethering. Careful lipoma debulking, which can be facilitated with a CO2 laser, must be performed while developing surgical planes and minimizing tension on the tethered cord. https://thejns.org/doi/10.3171/CASE25691.

To describe prenatal imaging findings and postnatal outcomes in fetuses diagnosed with saccular forms of closed spinal dysraphism (CSD). This retrospective single-centre study included fetuses diagnosed with non-genetic, non-syndromic CSD between January 2018 and June 2023. Prenatal ultrasound and MRI findings were reviewed, with postnatal outcomes assessed in those managed expectantly, focusing on neurosurgical interventions, motor function, and urologic and bowel outcomes. Eighteen cases were identified; twelve opted for expectant management and had postnatal follow-up. The most common lesion was dysraphic spinal cord lipoma (10/18, 55.6%), followed by limited dorsal myeloschisis (3/18, 16.7%), myelocystocele (3/18, 16.7%) and meningocele (2/18, 11.0%). Chiari malformation and related brain abnormalities were absent at the time of diagnosis in all cases. Most fetuses (88.9%, 16/18) had a low-lying conus medullaris, and 70.6% (12/17) had a sac wall thickness ≥ 2 mm. Postnatally, 75% (9/12) underwent surgical detethering. At ≥ 30 months, all children could walk independently with or without orthoses. However, urologic complications were common in children age ≥ 48 months: 80% (4/5) required clean intermittent catheterization (CIC), 60% (3/5) had urinary incontinence, and 40% (2/5) experienced bowel incontinence. Prenatal imaging features at the lesion level are key for diagnosing CSD. While motor outcomes are favorable, urologic and bowel dysfunctions are frequent in postnatal life.

Radical resection of spinal cord lipomas reduces the rate of re-tethering. Current conventional neurophysiological mapping techniques are not able to differentiate between crucial motor nerve roots and sensory roots. Enhanced differentiation could contribute to complete resection. We present our experience with a double-train paradigm to differentiate between motor and sensory roots. In children undergoing spinal cord lipoma resection, the double-train mapping paradigm was used with an inter-train interval of 60 ms. Given the longer recovery time due to the H-reflex, a single muscle response was presumed to be elicited from a sensory root, and a double muscle response from a motor root. The primary endpoint was postoperative neurological outcome and bladder function at discharge. We included 8 children undergoing 10 lipoma resections between 2016 and 2023. Double-train mapping was used in all cases. Motor and sensory roots were clearly differentiated in 6 cases and altered the course of surgery in 4 cases. Post-surgery, no sensory and motor function worsened within 3 months. Bladder function was stable in six and improved in two children. In two patients, bladder function worsened slightly at 3 months and 6 months, at which point one patient was re-operated on for re-tethering. Intraoperative mapping with the double-train paradigm reliably differentiated between motor and sensory nerve roots. Informing the surgeon on the specific function of a tethering root may help to maximize resection without risking major neurological deficits.

Terminal myelocystocele (TMC) is a rare form of spinal dysraphism which arises due to aberration in the secondary neurulation process involving the caudal cell mass. Terminal myelocystocele has been defined by Pang et al. based on essential and non-essential features. One of the non-essential features includes non dysraphic lipomas which do not tether to the neural placode. We are presenting two cases which meets all the essential criteria outlined by Pang et al. for TMC but also show the presence of a lipomatous component tethering to the neural placode, similar to a dysraphic lipoma. Through this article, we want to showcase a subset which represents "true" terminal lipomyelocystocele (TLMC), bridging the spectrum of spinal dysraphism between TMC and lipomyelomeningocele (LMM).

Intramedullary nondysraphic spinal lipomas are extremely rare among primary spinal cord tumors. These patients present with nonspecific sensory symptoms followed by deterioration of motor symptoms. As the safety margins for neurological preservation are thin, meticulously locating the extent of the tumor and choosing the resection modalities is essential. The authors report a rare case of a 35-year-old male who presented with progressive difficulty in walking for 6 months associated with numbness and tingling sensation in the bilateral upper and lower limbs. He was diagnosed with nondysraphic intramedullary cervicothoracic lipoma and underwent subtotal resection of the tumor. Nondysraphic intramedullary spinal cord lipomas are rare and may present as nonspecific neurological symptoms. Hence, they should be considered differentials of intramedullary spinal cord tumors. Surgery appears to be the mainstay of treatment.