Keywords
intramedullary dermoid cyst - cervical spinal cord - rare presentation - absence of
spinal dysraphism
Palavras-chave
cisto dermoide intramedular - cordão cervical medular - apresentação rara - ausência
de disrafia espinhal
Introduction
Inclusion cysts of the spinal cord are rarely intramedullary, with only a few cases
having been reported in the literature. Intraspinal dermoid cysts are commonly located
in the lumbar and thoracic regions and are usually associated with congenital spinal
dysraphism and dermal sinus. Intramedullary dermoid cyst in the cervical region without
spinal dysraphism ([Fig. 1]) is extremely rare, with only seven cases being reported in the literature to date.
We report a case of an intramedullary dermoid cyst in the cervical cord of an 18-year-old
female patient.
Fig. 1 Intramedullary dermoid cyst at C5–C7 level without spinal dysraphism.
Presentation
Our patient was an 18-year-old female, who presented with gradual progressive weakness
of muscles of both upper limbs and both lower limbs, weakness of the distal limb muscles,
more than the proximal muscle group, ongoing for 3 years in the form of difficulty
in holding objects, mixing food, and difficulty in walking, climbing, squatting on
the floor, etc.
Upon examination, power in the upper limbs was ⅗ on the right side and ⅘ on the left
side with weakness of hand grip (right-20%, left-30%). In the upper limbs, the triceps
and supinator reflexes were absent. The power in both lower limbs was ⅘ and with spasticity,
and the patient was able to walk with difficulty. The plantar reflex was extensor
bilaterally, with exaggerated ankle and knee jerks and the patient also sustained
clonus of both ankles. There were no sensory changes in the upper and lower limbs,
or in the rest of the body.
The MRI of the cervical spine with contrast study showed widening of the cervical
spinal cord from C5–C7 ([Fig. 2]). An intramedullary space occupying lesion was present, which was hypo intense on
T1 weighted images, hyper intense on T2 weighted images, and with peripheral ring
enhancement on contrast study. Also, “whorls” were seen within the lesion on T2 weighted
images ([Fig. 3]). There was associated excavation of the cervical vertebral bodies in the C5–C7
levels.
Fig. 2 T1-weighted magnetic resonance imaging focusing on intramedullary dermoid cyst at
C5–C7 level.
Fig. 3 Whorls seen on T2-weighted magnetic resonance imaging.
Operative Technique
The patient was operated under general anesthesia in prone position. An intraoperative
injection of methyl-prednisolone was given and continued in the postoperative period
for 23 hours at a dose of 30 mg/kg bolus over 1 hour followed by 5.4 mg/kg/hr for
23 hours. A midline incision extending from just below C2– D1 was made. The paraspinal
muscles were retracted laterally by sub periosteal dissection. A partial laminectomy
of C5, C6, C7 and D1 was performed.
After laminectomy, the cervical dura was found to be bulging and enlarged. The dura
was opened in the midline and retracted by stay sutures. The cord was enlarged, and
a low-grade torsion was noted. A small myelotomy was made in the root entry zone,
initially. About 1 to 1.5 ml of yellowish colored fluid was drained. The myelotomy
was subsequently extended rostrally and caudally. White shiny debris with hair ([Fig. 4]) was removed. Whitish pultaceous contents mixed with hair and teeth ([Fig. 5]) were removed. Complete excision of cyst along with the cyst wall was performed.
The myelotomy was left open. The dura was closed with 6-0 Prolene. The muscles and
skin were subsequently closed with absorbable stitches. Recovery from anesthesia was
uneventful.
Fig. 4 Intraoperative picture of dermoid cyst.
Fig. 5 Macroscopic image of the excised specimen showing its ectodermal derivatives.
Results
Immediately after the surgery, the patient's power in the lower limbs was ⅖ and ⅘
in the upper limbs. There was no respiratory distress. Over a period of 3 days, the
power improved to ⅘ in the lower limbs and ⅘ in the upper limbs. The catheter was
removed on the 10th postoperative day, and the patient was able to void urine naturally without any bladder
dysfunction. Bowel movements were normal, and there was no incontinence of feces.
The patient was able to walk with support on the 10th postoperative day. The wound healed well, and the stitches were removed on the 14th postoperative day, after which the patient was discharged.
Histopathology
The sections show that the cyst wall was lined by stratified squamous epithelium with
underlying dermis showing hair follicles, sebaceous glands, adipose tissue and cyst
filled with keratin debris ([Fig. 6]).
Fig. 6 Histopathology slide
Discussion
The common locations of dermoid cysts are:
-
Scalp (angle of eye and retro mastoid region)
-
Skull bones (intradiploic)
-
Intracranial, in the suprasellar region and posterior fossa
-
Intraspinal, mainly intradural, and associated with other spine defects.
The dermoid cysts are a developmental abnormality and arise from the nests of embryonic
ectoderm that get buried or trapped under the lines of fusion of the ectodermal folds
in the developing embryo.[1]
[2]
It is well known that the nervous system develops from the ectoderm. The cells on
the dorsal aspect of the developing embryo thicken to form the neural plate or placode
along the axis of the embryo. The neural plate bends and closes to from a tube called
the neural tube, from which the entire nervous system develops. The neural tube closes
in the dorsal midline first, and the closure then extends cranially and caudally so
that the anterior neuropore closes at 24 days and the posterior neuropore at 28 days.
Thus, as the neural tube closes last in the caudal part, that is the lumbo-sacral
region, there is a bigger chance that this process may be disturbed, and nests of
cutaneous tissue may get trapped within the developing tube, giving rise to dermoid
cysts. Hence, the propensity for the dermoid cyst to occur in the lumbosacral region.
Also, dermoid cysts are commonly associated with spinal dysraphism. This is because
the process that gives rise to spinal dysraphism is also responsible for the development
of the dermoid cyst.[3]
[4] The low incidence of dermoid cysts in the cervical region is likely related to the
embryological process of neural tube closure, which begins in the area of the neural
tube destined to become the lower cervical cord and proceeds rostrally and caudally.
Spinal inclusion cysts are usually intradural, intramedullary in the cervical spinal
cord region, with the other common lesions being neuroenteric cysts, arachnoid cysts,
epidermoid and dermoid cysts.[1]
[2]
Dermoid cysts usually present themselves in childhood, as a consequence of associated
anomalies or by symptoms of cord tethering and mass effects. However, in this case,
the patient had no associated developmental anomaly of the spine. Because of the absence
of any other congenital anomaly of the spine, the patient presented at a later age,
after she had developed significant symptoms, particularly in the left side of the
body. Total excision of the dermoid cyst was performed by standard micro neurosurgical
technique employed for other intramedullary tumors.
We could find three other cases [5]
[6]
[7]
[8] in which a dermoid cyst was in the cervical cord and was not associated with any
other congenital anomalies of the spine. In other reported cases,[6]
[7]
[9] the location of the dermoid cyst and the presence or absence of congenital anomaly
of the spine were not clear as they were dated before the advent of MRI. Hence, it
is difficult to ascertain whether these cases represent the “true” intramedullary
dermoid cyst or are part of a developmental defect.
Conclusion
The intramedullary location of the dermoid cyst in the cervical cord and the absence
of any congenital spinal dysraphism make this case a very unique and rare entity and
add to the reported cases of rare intramedullary space occupying lesions.
