Dermoid cysts are more frequent in childhood and comprise as little as 0.5-1% of intramedullary spinal tumors
5,6,7. Half of the spinal dermoid cyts that are intadural extramedullary tumors, while the other half is intramedullary located
8,9. Cervical or upper thoracic localization of dermoid cysts is a rare occasion, however, their conus level localization is common, as was in our case
10,11.
Spinal dermoid cysts are congenital and they develop through heterotopic embryological remnants or through focal expansion of dermal sinus along the conus or cauda. The cysts are usually accompanied with spina bifida and hemivertebra abnormalities,10 as was in our case.
The symptoms of spinal dermoid cysts usually develop slowly in time6,8,9. The most common complaint is back pain increasing in severity upon vertebral movements or valsavla maneuver. Intramedullary dermoid cyst cases often suffer from sensory and motor findings accompanied by the pain. Sensory deficits may be in the form of radicular or segmental paresthesia as well as dissociated loss of sense with insensitivity to pain and heat, and intact two-point-discrimination, position and deep tension sensation. Loss of strength due to motor involvement, atrophy and fasciculation, and disordered gait may be present. However, although less frequently, sphincter deficits, scoliosis and spinal subarachnoidal hemorrhages have been reported11,12. Like in our case, 50% of the cases with dermoid cysts at conus level also have sphincter deficits6,8.
The determination of bladder function disorders is difficult in children. Particularly the children only with sphincter deficit primarily apply to psychiatry, urology, nephrology and infectious diseases clinics12. Therefore, the diagnosis is delayed and the clinical picture is deteriorated by the time the diagnosis is established. Of the patients applying to psychiatry clinics for enuresis nocturna, 5% have organic etiologies11,5. Likewise, the primary pathology of 1-3% of the patients applying to urology clinics with neurogenic bladder picture has been found to be associated with a spinal mass6,2. Therefore, in the cases with frequent need for urination, continual drops after urination and unaccountable urinary tract infections, particularly in children, the pathologies of neurogenic origin should be taken into consideration, and spinal imaging must be performed.
Urine control is provided by the peripheral reflex arcus in the sacral segments of the spine. This arcus is controlled by cortical centers. The urination center of the spinal cord is located at S2-S4 levels of conus medullaris. Based on their localization, the lesions revealing the sphincter deficits are termed as above S2-S4 suprasacral, S2-S4 sacral, and under this level, infrasacral. For normal function of urination, intact innervation of the bladder is required. In suprasacral lesions, detrussor hyperreflexia, and in sacral and infrasacral lesions, detrussor areflexia are expected (Table 1).
The muscles of the bladder are essentially parasympathetic. Pelvic splancnic nerves with parasympathetic effect originate from the sacral cord (S2-S4). They terminate at the ganglion located on the bladder wall and internal sphincter muscle. Parasympathetic stimulus stimulates contraction of the detrusory muscle and dilatation of the internal sphincter, through which the bladder is emptied.
The sympathetic nerves of the bladder originate from the lateral horns of T12-L1-L2 segments and extend to the bladder muscles through inferior hipogastric plexus. Sympathetic nerves leads to the contraction of internal sphincter muscle; thus, urine is accumulated in the bladder.
Somatic fibres, on the other hand, are located in the anterior horn (S2-S4) of the sacral cord. These are called pudental nerves and innervate external sphincter. When urine pass through the internal sphincter, this muscle opens and remains open until the bladder is empty
The neurogenic bladder picture develops after somatic, parasympathetic, and sympathetic systems are affected by various factors. Sympathetic system is the first to be affected in the intramedullary masses compromising the bladder function. In the sympathetic system disfunctions, internal urethral sphincter will not contract adequately, thus, leading to initial findings of neurogenic bladder urine leakage after urination and stress-related incontinence7,8. Severely affected parasympathetic system, however, disrupts the detrusory mechanism, which results in a hypotonic and areflexed bladder. When both systems are involved, the patient not only loses his/her ability to empty the bladder but also develops incontinence due to sphincter deficit. While hypotonic bladder usually does not constitute a major risk for upper urinary tract, areflexed hypertonic bladder due to parasympathetic denervation may lead to reflux associated with high intrabladder tension.
The most severe reflux, which could lead to hydroneprosis, occurs in detrussory-sphincter dissynergies arising from incompatibility between the detrussory muscle and sphincter6,7. Normally the efferent stimuli arriving at the external sphincter via pudental nerve and the stimuli arriving at the detrusor through pelvic nerves of parasympathetic system inhibit each other with the help of collateral fibres, but do not activate simultaneously10. However, as a consequence of the dissynergie developing due to sacral spinal lesions, detrussory muscle contractions significantly increase the intrabladder tension against uncontrolled and irregular contractions of the external sphincter. This creates a reflux, most likely to result in hydrophrosis11,12. In our case, grade III hydrophrosis was due to the dissynergy between the pelvic-pudental nerves associated with the spinal mass.
In the diagnosis of intramedullary dermoid cyts, radiological evaluations have an important role. Direct radiographies may reveal vertebral corpus destruction, enlargement of interpedicular distuces, and vertebra anomalies. Lomber CT may show increased spinal diameter. However, the primary method of diagnosis is contrasted MRI.13Contrasted on MRI, the characteristic appearance of a dermoid cyst is hypointense on T1 and hyperintense on T2 with no contrast enhancement, as was in our case.
In differential diagnosis of spinal dermoid cysts, all spinal cord tumors should be suspected. They should particularly be distinguished from intramedullary located epidermoid cysts, ependimoma, astrocytoma, melanoma, lymphoma and metastases5,7. Furthermore, their differential diagnosis from demyelinized diseases, inflammatory myelites, paraneoplastic myelopathies presenting with sensory-motor and sphincter deficits should be well-established.
There are two goals in the treatment of spinal dermoid cyts: the treatment aiming at the sphincter deficit and the treatment of the mass. The former involves the use of pharmacological medications, which are anticolinergics, beta-adrenergic antagonists, alpha-adrenergic antagonists, for sphincter deficit. These agents show their effects by increas-ing the bladder capacity and decreasing the contraction force of the bladder at the same time11. The studies on the treatment of the mass indicated that the best approach was the total excision of the mass at an early period10,11. When the diagnosis is established at an earlier time, and the mass is totally excised, neurological and sphincter deficits have improved4,5. Total mass excision is possible for extramedullary dermoid cysts; however, in intramedullary dermoid cysts, the capsule adheres to the cord, as was in our case; thus, total excision may inflict additional neurological deficits. Long-term case analyses have shown that total excision of the mass including the capsule could lead to fibrous adhe-sions on the spinal cord10,11. Therefore, in the surgical interventions of spinal dermoid cysts, subtotal excision of the capsule is preferred. Literature reveals only one case of spinal dermoid cyst, which recurred 17 years later and surgically intervention was required13,14. The cyst of our case has not recurred within the four-year-follow up period.