Keywords
intramedullary - lipoma - dorsal - spinal dysraphism
Introduction
Lipomas, as we know, are universal tumor. Intramedullary lipoma of the spinal cord
constitutes less than 1% of all spinal tumors.[1] They are hamartoma as stated by few authors. They are mostly seen in the cervicodorsal
region in children.[1]
[2]
[3]
[4] They are rare in adults. In the literature, there are in total 12 reported cases
of intramedullary lipoma without spinal dysraphism in the dorsolumbar spine till date
as per our knowledge.[2]
Case Report
A 23-year-old man, who presented with spastic ascending paraparesis, with pain and
paresthesia of his left thigh. His weakness started in his the left lower limb for
the past 4 years and right lower limb for the past 2 years with involvement of the
bladder in the form of urgency and frequency. His bowel was constipated. On examination,
he had increased tone with a power of 3/5 in both the lower limbs. All modalities
of sensation were diminished below D6 bilaterally. His sensation for pain and temperature
were diminished more over the left side than the right side. His position sense was
impaired below knee over the left side and below ankle over the right side. Vibration
sensation was diminished below D6 vertebral level. Perianal sensation was impaired.
Abdominal reflex was absent in all four quadrants. Lower limb reflexes were brisk
and planters were extensor bilaterally. Romberg's sign was positive. Local examination
of the spine did not reveal any spinal dysraphic cutaneous lesions such as hair, sinus,
fistula, or dimple.
The magnetic resonance imaging (MRI) of his spine reveals a fairly well-defined intramedullary
expansile mass lesion with an exophytic component involving the cord parenchyma opposite
D5–D6 interspace to D8–D9 interspace. The lesion shows mixed signals predominantly
hyperintense both on T1WI and T2WI. The lesion measures (1.6 × 1.14) cm in cross section
and 7.56 cm in craniocaudal dimensions. The lesion shows patchy vertical line restricted
diffusion on diffusion-weighted imaging (DWI). On postcontrast study there is mild
peripheral enhancement. These findings are consistent with nondysraphic intramedullary
cord lipoma opposite D5–D6 interspace to D8–D9 interspace ([Figs. 1]
[2]
[3]).
Fig. 1 MRI showing a fairly well-defined intramedullary T1 hyperintense lesion extending
from opposite D5–D6 interspace to D8–D9 interspace.
Fig. 2 MRI showing a fairly well-defined intramedullary T2 hyperintense lesion extending
from opposite D5–D6 interspace to D8–D9 interspace.
Fig. 3 T2 fat suppressed MRI images showing hypointense signal (signal drop) suggestive
of lipoma.
Laminectomy was done at D5 to D8 level. A subpial intramedullary lipoma was visualized
as yellowish fatty mass on opening the dura. There was no well demarcation between
lipoma and the cord parenchyma ([Figs. 4]
[5]
[6]).Under microscope subtotal excision of the lipoma was done with great care not to
injure the underlying cord parenchyma. It was found to be densely adherent to the
spinal cord with numerous entering and exiting nerve roots encapsulated. The dura
was closed water tightly.
Fig. 4 Operative picture showing the yellowish lipoma with a very less demarcation between
normal cord parenchyma and the lesion.
Fig. 5 Intraoperative picture showing lipoma dissection.
Fig. 6 Figure showing the excised specimen.
Excised mass was sent for histopathologic examination that confirmed the fatty lipomatous
tissue consistent with cord lipoma ([Fig. 7]).
Fig. 7 HPE photograph showing normal fat cells consistent with lipoma.
Postoperatively patient improved, and on follow-up after 6 weeks, his lower limb power
was −4/5 bilaterally. There was no pain and paresthesia of his lower limbs. There
were persistent bladder disturbances in the form of increased frequency and urgency.
Discussion
Lipomas of the spinal cord in adult are very rare lesions . Intramedullary lipomas
constitute less than 1% of all spinal tumors.[1]
[2] In the literature till date, there are 12 reported cases of intermedullary lipoma
without spinal dysraphism situated in the dorsolumbar region.[2] They are mostly located in the cervicodorsal region and found mostly in children.[1]
[2]
[3]
[4] The origin of these lesions are thought to be due to embryonic inclusion in the
early fetal life at the time of neural tube closure.[5]
[6] Some authors also said that they are hamartomas that arise from fatty tissues, deposition
of fat in the connective tissue, and metastatic differentiation of embryonic meninges.[5]
[6] They may be associated with lipoma at other site in the same patient.[7] They are very slow-growing tumors, and so patients may present with a long duration
of symptoms. Symptoms are according to the location of the tumor. Our patient presented
with signs of compressive myelopathy with sensory, motor, and autonomic involvement.
MRI is the investigation of choice. In both T1W and T2W images, lipoma appears hyperintense,
and in fat suppression images, lipoma tissue appears hypointense. MRI images can give
a good tumor delineation from normal cord parenchyma. X-rays and computed tomographic
(CT) scan of the spine can give an overview of any bony deformity or any associated
congenital malformation or spinal dysraphism. Intramedullary lipoma dissection is
a challenge to a neurosurgeons as there is no well demarcation from the normal cord
parenchyma and the lesion. It is well established that total excision of the intramedullary
lipoma should not be tried, which may lead to a catastrophic result.[8]
[9] Use of carbon dioxide laser for resection is ideal for such lesions.[2]
[3]
[8] Intraoperative ultrasonography (USG) is also very useful to identify the extent
of the lesion.[8] We used microsurgical techniques for the excision of the lesion in our hospital.
Most of the cases improved neurologically after subtotal resection in a large case
series by Bhatoe et al using carbon dioxide laser and by Pruthi and Devi.[8]
[9]
Conclusion
Subpial and intramedullary lipoma of the dorsolumbar region in an adult without spinal
dysraphism is very rare. These benign lesion should be excised with extreme care not
to injure the normal cord parenchyma. The goal of surgery should be tumor debulking
and avoiding any neurologic deficit postoperatively.
