Evaluation of Spinal Lipoma in Children

Examination

Medical History

Salient features of the medical history include:

• Mode of presentation: Was the diagnosis based on skin findings, neurological symptoms, or incidentally identified on imaging studies?
• Motor developmental milestones: Age when first sitting, standing, and walking.
• Evolution of symptoms: History of spinal pain, leg pain, changes in foot posture, or alteration of gait.
• History of urologic symptoms: Continence history. In the precontinent child, this includes any history of urinary infections, urinary dribbling between voids, or changes in pattern of urination. In the child who has previously attained continence, any episodes of daytime or nighttime incontinence, urinary urgency, urinary frequency, or infection should be investigated.
• Associated anomalies treatments: Spinal lipomas can occur in association with other congenital anomalies, such as anorectal malformation or vertebral anomalies.
• Family history: Although lipomas are not typically familial, they can occur in the context or rare genetic disorders, such as Currarino syndrome (16).

Physical Examination

The following observations are important in the physical examination of children with lipomas. If present, the findings should be documented in the description of the physical examination.

• Midline skin anomalies: Appearance and specific location of any midline skin anomalies over the spine.

Spinal deformity.

• Asymmetry and other abnormal anatomy in lower extremities: Assessment of muscle bulk in the lower limbs for evidence of asymmetry or muscle wasting should be done. 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: MRC grading of muscle function should be documented, as this will be important in long-term surveillance. (This can be supplemented by gait analysis, if available.)
• Assessment of DTR: 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.

Laboratory Tests

Few laboratory tests are indicated for lipoma patients, but those recommended include:

• Full blood count
• Electrolytes
• Basic renal chemistry (urea, creatinine)

Radiologic Tests

Plain X-rays, Ultrasound

• Plain x-rays: Plain radiographs are rarely indicated in the evaluation of spinal lipomas and expose the child to unnecessary irradiation.
• Ultrasound of spine: Ultrasound is as sensitive as MRI for the detection of spinal lipomas in children aged up to approximately 3 months, after which the “acoustic window” at the lumbosacral junction obscures adequate visualization (30,32). A preoperative MRI is required for detailed analysis of the anatomy.
• Urological ultrasound: Ultrasound of the renal tract should be performed as part of the preoperative urological assessment.

CT Scans

• CT scans: CT scan exposes the child to radiation and are not routinely performed unless there are clear bony malformations indicated on the MRI that require elucidation.

MRI

Diagnostic MRI is indicated for all lipoma patients.

• Whole spine T1, T2, +/- FAT-SAT and CISS sequences: Whole spine MRI is indicated at the outset, but follow-up studies can be limited to the lumbosacral region. Sagittal and axial T1- and T2-weighted sequences should be performed at a minimum. FAT-SAT and CISS sequences can be used to better understand neural elements within the lipoma.
• Features to assess on MRI: Identify the type of lipoma (dorsal, transitional, chaotic, terminal) and any associated anomalies, such as vertebral malformations, syrinx, or coexisting dysraphic anomalies. Also assess the configuration of the neural placode (degree of rotation); this is helpful in planning the width of bony exposure.
• Brain MRI not indicated: Brain imaging is not routinely indicated (31).

Nuclear Medicine Tests

Radionucleotide scans (dimercaptosuccinic acid and mercaptoacetyltriglycine-3) are sometimes indicated in the presence of renal injury, but the indication for these is at the discretion of the urologist.

Electrodiagnostic Tests

• Not required for diagnosis: For the initial diagnosis of spinal lipomas, no specific outpatient electrodiagnostic tests are indicated.
• IOM essential during surgery: During the surgical intervention for spinal lipomas, IOM is a critical electrodiagnostic tool and is used to ensure the safety and integrity of the spinal cord and neural structures, particularly during detachment of the lipoma from the dura and resection.

Urological evaluation

Urological investigations may include any of the following:

• Renal tract ultrasound: This provides an assessment of the kidneys, ureters, and bladder and can identify associated malformations, thickening of the bladder wall, and evidence of urinary reflux.
• Noninvasive bladder assessment: Ultrasound of the bladder is performed before and after voiding (with the help of a nappy alarm when appropriate) to assess the efficacy of bladder emptying. Residual volumes of up to 20% can be normal and in isolation, do not indicate neuropathic bladder.
• Flowmetry: In older children, urinary flow rates are easy to perform, are repeatable, and can provide useful information on the efficiency of voiding.
• Catheter urodynamics: A urinary catheter is placed and the bladder is filled while intravesical pressure, volume, and leak point are assessed.
• Invasive urodynamics: A suprapubic catheter is placed, and urodynamic studies are performed as above. Because there is no catheter in the urethra, bladder emptying can be better assessed using this methodology.
• Precontinent child caveat: Atypical behavior of the bladder and sphincters is common in the precontinent child and is not necessarily indicative of neuropathic bladder dysfunction. Findings should be interpreted with care and in conjunction with pediatric urological expertise. This is particularly relevant for infants and young children.

Neuropsychological Tests

• Not indicated: Neuropsychological tests are not indicated.

Correlation of Tests

The following parameters should be considered when formulating a management plan for the child with lumbosacral lipoma:

• Clinical presentation: Is there evidence of neuro-orthopedic or urological dysfunction, such as lower limb weakness, muscle atrophy, foot deformity, pain, urinary tract infection, or urological evidence of neurogenic bladder?
• Symptom evolution: Are the symptoms/signs new or progressive? Have they been present since birth?
• Type of lipoma: Lipoma type is an important consideration. Not all lipomas have a similar natural history. Transitional, chaotic, and lipomas with extraspinal extension have high rates of deterioration and, therefore, may benefit from early intervention. Dorsal lipomas have a more indolent and favorable natural history and may warrant a more observational policy. Terminal lipomas have the highest likelihood of successful treatment.
• Age of the patient: In a precontinent child with a high-risk lipoma where there is a concern that bladder function may be at risk, the threshold for surgery should be lower than for an older child with established continence. In the latter case, an observational policy might be more appropriate.
• Clinical context: When spinal cord lipoma occurs in the context of a wider urogenital malformation (e.g., cloacal exstrophy or anorectal malformation), it is more often the urogenital malformation that will dictate the long-term continence prognosis rather than spinal cord tethering. In such cases, motor function, foot deformity, and pain are the more important clinical indicators for untethering surgery.
• Surgical experience and availability of neurophysiological expertise: Conus region lipomas can present a formidable surgical challenge, with a significant risk of causing neurological and urological injury. More radical techniques of lipoma resection should not be undertaken unless there is access to appropriate IOM.