The human tail and spinal dysraphism

The Human Tail and Spinal Dysraphism By Allan

Joel Belzberg,

Stanley

Terence

Myles,

and Cynthia

Lucy Trevenen

Calgary, Alberta 0 Recent publications have endeavoured to differentiate between the true, or vestigial tail, and the pseudotail by clinical and pathological examination, and have indicated the benign nature of the true tail. The true tail arises from the most distal remnant of the embryonic tail, contains adipose, connective, muscle, and nerve tissue, and is covered by skin. Pseudotails represent a variety of lesions having in common a lumbosacral protrusion and a superficial resemblance to vestigial tails. A review of the case reports indicates spina bifida to be the most frequent coexisting anomaly with both. A review of occult spinal dysraphism shows it to be associ-

CASE

REPORTS

Case 1

underlying spinal dysraphism. Preoperative assessment must include a complete neurological history and examination as well as computed tomographic or magnetic resonance imag-

A 4-day-old girl, born after an uncomplicated pregnancy, was admitted to Alberta Children’s Hospital for investigation of a lumbar mass. At the b level was a polypoid lesion 2.5 cm in height, 1 cm in diameter, soft, nontender, and nonfluctuant (Fig 1A). Asymmetric buttock creases and difficulty eliciting a perianal wink prompted a myelogram, which demonstrated deviation of the spinal cord. Follow-up metrizamide-enhanced computed tomography (CT) scan suggested a communication between the intraspinal contents and the subcutaneous mass. At operation the mass was excised (Fig 1B). Dissection was then continued to the lumbodorsal fascia and a two-level laminectomy was performed. The dura was opened proximally, showing a thickened filum terminale entering a tract communicating between the subcutaneous mass and the dura. The filum was divided and immediately retracted 1 cm, indicating tethering of the cord. A primary closure was then performed. There were no postoperative complications. Microscopic examination demonstrated the mass to be composed of lobules of mature adipose tissue. In addition, connective tissue, occasional small nerves, and clusters of ganglion cells were seen.

ing. Copyright

Case

ated with cutaneous signs in more than 50% of instances. Three cases of spinal dysraphism with tail-like cutaneous structures are described and their radiological, operative, and pathological findings presented. The classification of each of the appendages into true tail or pseudotail remains obscure. Although the finding of these three tails was the subject of much curiosity, surgical treatment was clearly designed to adequately deal with the associated dysraphic state. The presence of a tail-like appendage in the lumbosao ral region should alert the clinician to the possibility of

INDEX

o 1991 by W.B. Saunders Company

WORDS:

Human

tail;

spina bifida;

tethered

cord

syndrome.

T

HE HUMAN TAIL has been classified as either a true (persistent vestigial) tail or a pseudotail.‘. The true tail is thought to be a benign condition not associated with any underlying cord malformation.4 Our recent experience with three infants with tail-like appendages demonstrates the difficulty differentiating between true tail and pseudotail and the need to investigate for an associated dysraphic state. A “vestigial tail” describes a remnant of a structure found in embryonic life or in ancestral forms. The human fetus loses all evidence of the tail bud by stages 20 to 23 (the eighth week).5 Harrison suggested that the vestigial tail arises from the distal unvertebrated mesodermal portion of the embryonic tail6 The human vestigial tail lacks bone, cartilage, notochord, and spinal cord. It contains a central core of mature fatty tissue divided into small lobules by thin fibrous septa. Small blood vessels and nerve fibers are scattered throughout. Bundles of striated muscle fibers, sometimes degenerated, tend to aggregate in the center.“2.7.8 The pseudotail is often short, stump-like, and occasionally bulging. It may be composed of teratomatous elements, adipose tissue, or cartilage.3.p’0 ./ourna/ofPed;atr;c

Suroerv.

Vol 26. No 10 (October), 1991: DD 1243-1245

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A 3-month-old girl was admitted to the Alberta Children’s Hospital for removal of a hpomyelomeningocele that had been diagnosed at birth. Pregnancy was complicated by mother’s asthma, for which she received Ventolin, Beclovent, and Prednisone occasionally. The patient had been delivered by cesarean section because of breech position. Examination showed a 5 x 5 cm mass in the sacral area. When the infant was crying, the mass protruded 3 cm. There was also a 5-mm-diameter appendage separate from the main sacral mass and to the right of the anus. She had normal motor function and tone in the lower limbs. There was decreased sensation to pinprick on the perineum and no anal wink. Myelographic and CT investigation showed the spinal cord entering a lipomatous mass at the S, level. At operation, a sacral lipoma was found and was noted to be continuous with the skin appendage. The appendage was resected, and the lipoma then dissected from the subcutaneous tissues. The lipoma extended into the spinal canal through a bifid S,. A Iaminectomy was performed and the dura entered proximally. At the S, level, the cord angled dorsally and was adherent to the dura and hpoma. The dura was gradually separated from the cord and the hpoma removed with the aid of an ultrasonic aspirator. A thickened filum terminale was divided. A small amount of lipoma

From the Division of NeurosurgeT and the Department of Pathology, Alberta Children’s Hospital and the Departments of Clinical Neurosciences and Pathology, Universiiyof Calgary, Calgay, Alberta. Date accepted: August 13, 1990. Address reprint requests to Allan J. Belzberg, MD, Deparhent of Neurosurgery,Johns Hopkins Hospital, Meyer 7-113, 600 N Wolfe St, Baltimore, MD 21205. Copyright o I991 by W B. Saunders Company 0022-3468/91/2610-0024803.00l0 1243

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BELZBERG, MYLES, AND TREVENEN

entering the distal cord was left in situ. Primary closure was achieved using a dural graft. The postoperative course was complicated by infection and a cerebrospinal fluid leak requiring replacement of the dural graft. On microscopic examination, the resected fragments consisted of mature adipose tissue, irregular spaces lined by ependyma, and small foci of glial tissue (Fig 2).

Case 3 A 3-week-old boy was admitted to Alberta Children’s Hospital for investigation of a sacral appendage. He was delivered 3 weeks premature by cesarean section after failure to progress following 24 hours of labor. Examination showed a 3 x 1.5 cm nontender, soft appendage in the sacral region. Neurological examination was completely normal. Plain x-ray of the sacrum demonstrated normal bony structures. At operation an elliptical skin incision was made around the base of the appendage. The stalk of the appendage was identified and followed through a defect in the lumbodorsal fascia and bifid laminae to the dura. The dura was opened and showed an intradural hpoma continuous with the skin appendage. The stalk was divided at the level of the lumbodorsal fascia. The intradural lipoma was debulked, leaving a small portion attached to conus medullaris. The thickened filum terminale was divided and immediate ascent of the cord was witnessed. Primary closure of the dura,

Fig 2. Resected fragment from intradural portion of mass (case 2) demonstrating ependymal lined spaces with surrounding glial tissue.

fascia, and skin was achieved. There were no postoperative complications. Microscopic examination of the excised mass demonstrated mature adipose tissue with occasional nerves. A short sinus tract lined by squamous epithelium extended into the dermis.

DISCUSSION

Fig 1. (A) Four-day-old girl (case 1) with lumbar “tail” measuring 2.5 x 1 cm. (B) Excision of the appendage and underlying adipose tissue.

Three case reports of spinal dysraphism with taillike cutaneous structures have been presented. The classification of each of the appendages into true tail or pseudotail remains obscure. Surgical treatment was clearly designed not only remove to the tail, but also to deal adequately with the dysraphic state. Skin lesions associated with spinal dysraphism are a well documented finding. A publication reviewing 200 cases of occult spinal dysraphism showed the condition to be associated with cutaneous signs in more than 50% of instances.” Skin-related lesions included subcutaneous tumors, skin dimples or sinuses, hemangiomas, local hairiness, and pigmented nevi. Hoffman et al, in reviewing 97 cases of lipomyelomeningocele, found the most common presenting complaint to be a fatty mass in the lumbosacral region.” Five of the patients presented with a tail-like caudal appendage.

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A recent review summarized case reports of human tails published from 1859 to 1983. Of the 33 cases reviewed, 23 were classified as true tails, and 10 as pseudotails. Spina bifida was the most frequent coexisting anomaly.’ The distinction between the vestigial tail and the pseudotail on clinical examination is dubious at best. These three case reports serve to emphasize the need for complete preoperative investigation of the frequently associated dysraphic state. Tethered cord syndrome has been attributed to a variety of the pathological entities of dysraphism, including those that can present with a tail-like appendage. Early surgical intervention can prevent this complication.“.” Too much regard to the tail with disregard of associated anomalies may prevent accurate diagnosis and delay appropriate patient management. Spiegelmann et al postulate that, from the embryological point of view, the vestigial tail is not related to the neurospinal axis. In addition, they conclude that the diagnosis of true human tail from clinical and plain x-ray examination is enough to establish a benign condition, and that the resection can be performed for cosmetic reasons without the need for

subfascial exploration.4 However, in their single case report of a vestigial tail, CT scan showed spina bifida at L,, and an underlying lipoma at the base of the tail. The lumbosacral fascia was explored but no defect or associated tract was found. In sharp contrast is case 3, in which, despite a normal neurological examination, normal plain x-ray of the spine, and clinical classification of true tail, subfascial exploration showed a lipomyelomeningocele. Investigation of patients with skin appendages, as always, begins with history and examination. Careful attention should be paid to the neurological examination. Plain x-ray of the lumbar spine may fail to demonstrate the dysraphic state. Thus, CT, metrizamide myelography in combination with CT scanning, or magnetic resonance imaging of the lumbar spine is recommended.” Classification of a human tail as either a true (persistent vestigial) tail or a pseudotail does not diminish the need for comprehensive preoperative investigation. Definitive treatment of a patient with a tail-like appendage may require surgical exploration of the intraspinal contents to prevent future complications of the often associated dysraphic state.

REFERENCES 1. Dao AH, Netsky MG: Human tails and pseudotails. Hum Path01 15:449-453,1984 2. Kissane JM. Smith MG: Pathology of Infancy and Childhood. St Louis, MO, Mosby, 1967, pp 232-235 3. Potter EL, Craig JM: Pathology of the Fetus and Infant (ed 3). Chicago, IL, Year Book, 1975 4. Spiegelmann R, Schinder E, Mintz M, et al: The human tail: A benign stigma. J Neurosurg 63:461,1985 5. Moore KL: The Developing Human (ed 2). Philadelphia, PA, Saunders, 1977, pp 70-73 6. Harrison RG: On the occurrence of tails in man. Johns Hopkins Hosp Bull 12:96-101, 1901 7. Ledley FD: Evolution of the human tail. A case report. N Engl J Med 306:1212-12151982 8. Lundberg GD, Parsons RW: A case of a human tail. Am J Dis Child 104:72-73,1962 9. Parsons RW: Human tails. Plast Reconstr Surg 25:618, 1960

10. Salisachs LG, Gubern AM: Phylogenie et ontogenie des teratomes sacro-coccygeins et de l’appendice caudal. Ann Chir Infant 9:125, 1968 11. Tavafoghi G, Ghandchi A, Hambrick G, et al: Cutaneous signs of spinal dysraphism. Arch Dermatol 114:573, 1978 12. Hoffman HJ, Taecholarn C, Hendrick EB, et al: Management of lipomyelomeningoceles. J Neurosurg 62:1-g, 1985 13. Lingren AL, Tornberg B: Svanslik missbildnig med teratoid komponent. Nord Med 59:193,1958 14. Pang D, Wilberger JE: Tethered cord syndrome in adults. J Neurosurg 57132-47, 1982 15. Yashon D. Beatty RA: Tethering of the conus medullaris within the sacrum. J Neurol Neurosurg Psychiatry 29:244-250, 1966 16. Harwood-Nash DC, Fitz CR, Resjo IM. et al: Congenital spinal cord lesions in children and computed tomographic metrizamide myelography. Neuroradiology 16:69-70.1978