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| Year : 2001 | Volume
: 49
| Issue : 3 | Page : 243-6 |
Spinal congenital dermal sinus : an experience of 23 cases over 7 years.
Jindal A, Mahapatra AK
Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi--110 085, India.
Correspondence Address:
Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi--110 085, India.
[email protected]
Spinal congenital dermal sinus is a rare entity, which supposedly results from the failure of neuroectoderm to separate from the cutaneous ectoderm during the process of neurulation. The present study was undertaken to know the clinical profile of these patients, to study associated anomalies and to assess the results of surgical intervention. We had 23 patients with male : female ratio of 9:16. Only 2 patients were below 2 years of age and most cases (16) were between 2-16 years (mean age =10.2 years). Lumbar region (17 cases) was most frequently involved, followed by lumbosacral and thoracic region in 3 patients each. Only three patients were asymptomatic at the time of presentation. Most of the cases presented with evidence of neural compression or tethered cord syndrome. Only one case presented with spinal abscess. The motor, sensory and autonomic deficits were seen in 20, 11 and 12 patients respectively. Scoliosis and CTEV (congenital talipus equino varus) were the common associated anomalies. MRI revealed associated dysraphic state of spinal cord in 21(>90%) cases. All patients underwent surgical exploration and repair of dysraphic state and excision of the sinus. None of the asymptomatic patients deteriorated. Overall 8 patients improved, 14 got their neurological status stabilized, including 3 asymptomatic cases. Only one patient deteriorated. Postoperative wound infection was seen in 2 cases. As age advances, the chance of developing neurological deficit increases. Associated dysraphic state should be looked for and treated simultaneously, using microsurgical technique, whenever possible. It is better to treat all these cases with aggressive surgical intervention before the neurological deficits appear.
How to cite this article:
Jindal A, Mahapatra A K. Spinal congenital dermal sinus : an experience of 23 cases over 7 years. Neurol India 2001;49:243 |
Spinal congenital dermal sinus (SCDS) is a rare entity, which supposedly results from failure of neuroectoderm to separate from the cutaneous ectoderm during the process of neurulation.[1],[2],[3] The Spinal congenital dermal sinus (SCDS) is a rare entity, lesions are most frequent in lumbar and lumbosacral which supposedly results from failure of region followed by occipital region. Patients with SCDS usually present with meningitis and/or mass effect of associated inclusion tumours (epidermoids and dermoids) or with tethered cord syndrome. SCDS is a unique form of spinal dysraphism, which has innocuous external appearance, but the underlying tract may extend over several spinal levels and can end anywhere between dura and spinal cord or filum.[4] The neurological examination is reported to be normal in the early childhood. However, as the age increases there is more chance of neurological deficit, which tends to be more profound. The present study was undertaken to know the clinical profile of the patients presenting with SCDS and to study associated anomalies.
The study included 23 patients, 16 females and 9 males. Most patients (16) presented between 2-16 years of age. Five patients were more than 16 years of age while two were of 2 years (mean age of presentation-10.2 years). Every patient underwent a detailed neurological examination and a complete radiological workup to delineate any underlying / associated spinal abnormalities. SCDS was located most frequently in lumbar region (17 cases) [Figure. 1], followed by dorsal and lumbosacral region in 3 patients each. It was astonishing to note that most (20/23) of our patients presented with neurological deficits. Only 3 patients were referred to us by the paediatricians on the basis of this cutaneous marker alone. All the asymptomatic cases were below 4 years of age. Motor deficit was seen in 20 cases. The deficit was in the form of limb weakness and atrophy, with or without gait disturbance. Sensory deficit was seen in 11 cases. Twelve patients had bladder/bowel involvement at presentation. Associated skeletal anomalies were noticed in 6 cases. Scoliosis was the most common finding and was seen in 4 cases, followed by congenital talipus equino varus (CTEV) in 3 cases. MRI was the investigation of choice and was performed in all cases. MRI revealed the relationship of the dermal sinus to the dural sac [Figure. 2] and also gave information regarding associated abnormalities in the cord. Associated dysraphic state of spine or inclusion tumours were seen in 21 cases (>90%). Epidermoid [Figure. 3] and dermoid tumour was seen in 5 and 4 cases respectively. Split cord malformation was seen in 6 cases and filum abnormality was seen in 5 cases [Table I].
Surgical Intervention : The aim of surgery was to excise the sinus tract completely and to correct the dysraphic state in the same sitting. Midline vertical incision was used, encircling the sinus opening. The sinus tract was traced till its end and excised completely. Intraspinal pathologies like split cord malformation were dealt accordingly i.e. dermoid and epidermoids were decompressed or excised; myelocele and lipomeningo-myeloceles were repaired; and detethering of the cord was done in case of tethered cord. Postoperative follow-up ranged from 6 months to 6 years (mean-2.8 years).
[Table II]
Of the 3 asymptomatic cases, none developed fresh deficit. Motor deficit (present in 20 cases) stabilized in 12 cases and improved in 7 cases. Two patients developed fresh deficits in the postoperative period and one of them improved to preoperative status, 3 months later. Sensory improvement was seen in 2 cases and sensory deficits stabilized in 8 cases. Of the 12 incontinent patients, 6 improved and 6 remained the same. Wound infection was the only complication seen in the immediate postoperative period in 2 cases. Of these, one had intraspinal abscess following infection of epidermoid. Overall, 8 patients showed improvement, neurological status stabilized in 14 cases and one patient deteriorated neurologically.
A spinal congenital dermal sinus consists of a tract lined by stratified squamous epithelium found on or near the midline and is thought to result from the abnormal adhesions (or incomplete disjunction) between the neuroectoderm (destined to form the neural tube) and the cutaneous ectoderm.[5],[6],[7],[8] The inward extent of the tract depends upon the extent of adhesions and may vary from deep fascia to the spinal cord. The tract elongates during the development, due to ascent of the cord and may traverse several levels within the epidural space before entering the subarachnoid space. Disorder of the notochord formation with sagittal splitting of the spinal cord and persistence of the dorsal cutaneo-endo-mesenchymal fistula has also been suggested as a cause of dermal sinus formation.[7],[9] The squamous lining of SCDS may be encased in dermal and neurological tissue. Within the tract, one may find nerve or ganglion cells or fat, blood vessels, cartilage and meningeal remnants.[10],[11] SCDS may be associated with other abnormalities of the ectodermal, mesodermal or neural crest derivatives such as meningomyelocele or lipomeningomyelocele, reflecting a common ontogenic disorder. The dermal sinus is seen in 1540% cases of split cord malformations.[9],[10] In the present series also, 6 patients (25%) had split cord malformation associated with SCDS. Nearly 60% of the dermal sinus tracts enter the subarachnoid space and 27% are attached to the neural elements of the conus, cauda equina or filum terminale.[12] The tract may end blindly within the extradural space in 1020% cases.
Sinus tracts can occur anywhere from occiput to sacrum. Cervical area is least involved (<1% cases). Thoracic area is involved in 10% cases, lumbar and lumbosacral area in 40% and 12% patients respectively, sacrum in 23% and sacrococcygeal junction in 13% of cases.[13] Most patients in this study, had lumbar and lumbosacral involvement, followed by involvement of thoracic region. Dermoid and epidermoids are known to arise within focal expansion along the tract in approximately half of all dermal sinuses.[14],[15] We had 9 patients (39%) with these inclusion tumours on the MRI evaluation. However, filum abnormalities, not very well reported earlier, were encountered in 5 cases (22%). There is a small male preponderance reported in literature; however, in our series, females outnumbered males (16:9). All midline skin dimples (or SCDS) above the intergluteal fold must be assumed to communicate intraspinally and those below the top of crease are blind sacrococcygeal dimples not requiring exploration. SCDS provide a portal of entry for infection to travel upto spinal cord and can cause meningitis. Intraspinal abscessess are known to occur in about 50% cases. Abscess formation may occur intramedullary or involve the epidural or subdural spaces with subsequent extension over many vertebral levels.[16],[17] However, these complications were rare in our experience, with only one patient presenting with intraspinal abscess. There was no patient with recurrent meningitis. Most of our patients presented with neural compression. It is said that nearly all patients with SCDS have intact neurological function at birth. Neural compression from inclusion tumours or the tethered spinal cord is more common with increasing age of patients. It is possible that the malformation has gone unnoticed during childhood. Due to this reason, most (87%) of our patients presented with neurological deficits.
Conventional X-ray of spine has a limited role in evaluation due to immature calcification in children of less than 18 months of age. No associated soft tissue (cord) anomalies can be demonstrated with these lesions.[4] However, X-ray can provide indirect evidence of inclusion tumours by showing increased interpedicular distance and scalloping of the vertebral bodies. MRI has emerged as the investigation of choice and can demonstrate extraspinal tract path, inclusion tumours and associated spinal dysraphism.[18] MRI reveals a wealth of information in all these cases. Postoperative complications are few and easy to manage. Our results indicate that once a patient developed deficit, there is about 40-50% chance of improvement in deficit and 50% chance that deficit will stabilize. The risk of neurological deterioration is only 5%. The patients presenting at later age had more chance of developing deficits. One should have a high index of suspicion for all the dimples above the intergluteal fold, despite a normal examination or neuroradiologic studies. Midline should be carefully examined whenever a child suffers from meningitis, especially when an unusual organism is cultured. Conservative treatment of SCDS is not recommended. Surgery should be carried out prophylactically, in advance of deficits, to maintain normal neurological function.
All patients with spinal congenital dermal sinuses (SCDS) should be offered aggressive surgical treatment in the form of total excision of sinus tract and correction of spinal malformation, as soon as diagnosed. Chance of preserving and improving the neural function is high (95%).
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