Presentation of Spinal Lipoma in Children

Symptoms and Signs

Not all patients with spinal lipomas will experience symptoms or signs. The severity of symptoms can vary depending on the size and location of the lipoma.

• Asymptomatic: Many patients are identified during the asymptomatic phases. Approximately 30% of lipomas are ostensibly asymptomatic at the time of presentation but are at risk of causing neurological or urological issues later.
• Pain: Both acute and chronic back or leg pain can be manifestations of spinal cord tethering. This symptom is more predominant in adolescents and adults compared with young children. Pain tends to respond well to untethering surgery. Leg pain due to tethering is often poorly localized and nondermatomal.
• Abnormal gait: Spinal lipomas can lead to gait deterioration. Mechanisms for this include ankle/foot weakness, pain, and spinal deformity.
• Neurological symptoms: These encompass motor weakness, muscular atrophy, mixed deep tendon reflex abnormalities, spasticity, and sensory abnormalities. Typical tendon reflex changes comprise brisk knee reflexes with reduced or absent ankle reflexes.
• Sensory changes: Patients with spinal lipomas may experience changes in sensation, including numbness or tingling. Neuropathic skin ulceration can be seen in the feet or toes.
• Bladder or bowel dysfunction: Neurogenic sphincter dysfunction is arguably the most important complication of spinal lipoma. Symptoms include failure to attain (or secondary loss of) continence, urgency of micturition, recurrent urinary infections, and urinary leakage due to poor sphincter tone. Urological testing reveals anomalies such as incomplete emptying, irregular flow rates, and low leak pressure. Bowel issues rarely occur in the absence of bladder involvement, but can include constipation, diarrhea, or various degrees of fecal soiling.
• Scoliosis: Spinal lipomas can be associated with scoliosis or kyphosis. This may be a direct consequence of tethering or due to associated vertebral anomalies.
• Foot deformities: Varus or valgus foot deformity, leg deformities or asymmetry, and conditions such as hammer or claw toes can develop due to asymmetric innervation of agonist/antagonist muscle groups around the ankle or foot.
• Cutaneous signs: A subcutaneous fatty mass near the midline of the spine is often present, covered with intact skin. A skin dimple, false tail, or hemangioma often co-exists.

Patterns of evolution

• Uncertain natural history: It is commonly assumed that the natural history of conus lipomas is poor, with inevitable deterioration if left untreated. However, this assertion has been challenged by two natural history studies. Kulkarni et al. demonstrated that asymptomatic lipomas have a 33% probability of deterioration over a 9-year span (25). Wykes et al. reported a 40% chance of deterioration over a decade (26). This study suggested that the risk of deterioration was more significant for females and those with transitional lipomas and/or terminal syrinx (26).
• Natural history possibly related to lipoma type: More recent studies indicate that lipoma type has an impact on natural history. Dorsal lipomas and transitional lipomas in which the conus appears intact on imaging have a low risk of deterioration (27). In contrast, lipomas in which the placode extends completely or partially out of the spinal canal are associated with a high rate of long-term neurological disability, with or without surgery (28).

Time for evolution

• Chronic progression: When deterioration occurs, this tends to be slow, with gradual loss of function over months or years.
• Acute presentation possible: Acute deterioration is rare but has been described following hyperflexion injuries (12) — for example, during sport or childbirth (29).

Evaluation at Presentation

• Establish baseline: Establishing a clear baseline of neurological and urological function is important at presentation.
• Perform comprehensive evaluation: Children with spinal lipomas require a comprehensive evaluation, comprising a detailed medical history, assessment of motor and sphincter function, and neuroimaging studies.

History and Physical Examination

• Midline anomalies: Note the appearance and specific location of any midline skin anomalies over the spine or evidence of spinal deformity.
• Abnormalities in lower limbs or gait: Assess muscle bulk in the lower limbs for evidence of asymmetry or muscle wasting. Foot and ankle position should be inspected for signs of talipes or altered foot arches. In ambulant children, gait should be observed; asking the child to tiptoe and heel walk can be useful to identify signs of asymmetry or weakness.
• Assessment of muscle power: British Medical Research Council (MRC) grading of muscle function should be documented, as this will be important in long-term surveillance.
• Altered lower limb reflexes: Lower limb reflexes can be altered in children with lipoma; a common combination is normal or exaggerated knee reflexes but diminished or absent ankle reflexes.

Imaging

After examining the child, imaging is typically performed to confirm the suspicion that a spinal lipoma may be present.

• Ultrasound: Until the child is aged approximately 3 to 4 months, spinal ultrasound can provide excellent views of the terminal spinal cord and an estimate of the anatomical level of the conus. In this age group, ultrasound is as sensitive as MRI for the detection of spinal dysraphism (30).
• MRI: MR imaging for spinal lipomas in the neonatal period is rarely indicated. Image quality is often poor, and, in the absence of clinical symptoms or signs, MRI can be safely deferred until the infant is aged 3 to 4 months. Standard T1 and T2 sequences in both axial and sagittal plane are minimum requirements. FAT-SAT and CISS sequences can optimize the assessment of the conus and associated nerve roots. In nonsyndromic cases, imaging of the lumbosacral spine will suffice. There is little diagnostic yield from imaging the whole spine (31).

Urological evaluation

• Urological history and examination required: Urological assessment should be performed in all children with spinal lipomas. Solicit pediatric urological expertise to determine the most appropriate investigations and to interpret the findings.
• “Atypical” urinary function common in precontinent children: It is important to note that, in the precontinent child, atypical behavior of the bladder and sphincters is common and is not necessarily indicative of neuropathic bladder dysfunction. Expert interpretation of findings is essential.

Intervention at Presentation

The surgical anatomy of spinal lipomas can be treacherous; nuanced decision-making is required based on many factors, including the type of lipoma, the age and clinical status of the patient, and the experience of the surgeon. The following points should be considered:

• Asymptomatic child and risk of progression: Natural history studies suggest that deterioration is not inevitable (25,26). Certain lipoma types (for example, where the conus appears intact) have a favorable natural history. In infants, the role of prophylactic surgery is controversial. In young, asymptomatic children, a policy of close surveillance can be an appropriate strategy (27). In older children where continence is established and there are no motor or neurological symptoms, a policy of surveillance is usually indicated.
• Extent of resection: Partial resection of lipomas has low surgical morbidity but late deterioration due to retethering is frequent. The long-term outcome following partial resection is worse than natural history (2,10).
• Children with symptomatic or complex lipomas: Surgical intervention should be considered for children with symptoms/signs or with evolving deficits. Complex lipomas — for example transitional, chaotic, and those with extraspinal location of the placode — appear to be at high risk for deterioration. These may warrant prophylactic surgery.
• Lipomas associated with complex anorectal or genitourinary malformations: Where lipomas occur in the context of complex anorectal or genitourinary malformations, the anatomical effects of these malformations typically have a much greater impact on continence than the effects of spinal cord tethering.
• Timing of surgery when indicated: Urgent intervention is rarely required, and appropriate time should be invested in counseling the parents.

Stabilization

Severe acute, evolving symptoms: In rare instances, patients present with acute onset of symptoms such as severe pain, rapidly progressing weakness, or loss of bowel/bladder function. In these instances, immediate stabilization is required, and urgent neurosurgical evaluation is warranted.

• Slowly evolving or stable symptoms: Most patients present with stable or slowly progressive symptoms such as mild weakness or sensory deficits. In these cases, treatment may require a more measured approach involving observation and close monitoring for any changes or progression in symptoms and, possibly, elective surgery.

Preparation for Definitive Intervention, Nonemergent

Preparation for the surgical treatment of spinal lipoma includes:

• Medical evaluation: Medical evaluation and an assessment of the impact of comorbidities; for example, in syndromic cases or genitourinary malformations (e.g., cloacal exstrophy).
• Imaging studies: Good quality MRI of the lumbosacral spine is indicated in all cases. X-rays and CT scan rarely provide additional information.
• Urological evaluation: See Evaluation at Presentation, Urological evaluation.
• Assessment by physical therapist: Baseline physical therapy assessment and muscle charting is necessary.
• Education and counseling: The family (and patient, where appropriate) need detailed information about the procedure, anticipated (realistic) outcomes, potential complications, and postsurgery expectations. This includes the risks of wound-related complications, the need for further surgery, and the potential need for intermittent catheterization on a temporary or permanent basis. The role of surgical intervention versus observation should be discussed.

Preparation for Definitive Intervention, Emergent

• Rare: Emergency surgery for spinal lipoma is extremely uncommon.
• Acute deterioration should prompt whole-spine MRI: If acute deterioration occurs, a whole-spine MRI should be performed prior to surgery.

Admission orders

When admitting a patient with a spinal lipoma, the following orders need to be considered:

• HOB, positioning, and activity: No restrictions are indicated before surgery.
• Vital signs: Baseline VS should be established.
• Skin decontamination: Preoperative bathing with antiseptic soap to ensure optimal cleanliness of the perineal region is required.
• IV fluids: Patients with spinal lipomas may require fluids to maintain adequate hydration and electrolyte balance in the postoperative period. Preoperative IVF are not usually indicated.