Congenital malformations - Edocr

CHAPTER 49 SACRAL DIMPLE AND OTHER CUTANEOUS MARKERS 343
Figure 49-5. A human tail (Reprinted with
permission from Guggisberg D, Hadj-Rabia S,
Viney C, et al. Skin markers of occult spinal dysraphism
in children: a review of 54 cases. Arch
Dermatol. Sep 2004;140(9):1109–15.Copyright
2004, American Medical Association. All rights
reserved.)
or persistent vestigial tail is a caudal midline appendage
consisting of a central core of muscle,
adipose tissue, connective tissue, blood vessels,
and nerves (Fig. 49-5). A true tail may have
spontaneous or reflex motion. In contrast, a
pseudotail is a caudal protrusion of normal or
abnormal tissues such as adipose tissue, cartilage,
or teratoma. These lesions have been associated
with occult spinal dysraphism.
Hyper- and hypopigmented lesions have
also been reported in association with occult
spinal dysraphism but these associations are less
clearly defined.
SIGNIFICANCE OF AN EARLY
DIAGNOSIS OF OCCULT SPINAL
DYSRAPHISM
The term occult spinal dysraphism includes many
different congenital malformations of the spine
such as spina bifida occulta, diastematomyelia,
tethered cord, intraspinal lipoma, dermal sinus,
dermoid cysts, and lipomyelomeningoceles among
others. Abnormalities of the conus medullaris and
filum terminale are the most common findings
in infants with occult spinal dysraphism. The
conus is usually prolonged and filum terminale
is thickened and these structures may be “tethered”
or fixed at their caudal end. Tethering of
the cord can result in mechanical traction on the
cord in some cases as the bony spine grows
faster than the spinal cord in early infancy. The
cord traction may also impair the microcirculation
of the cord, causing progressive ischemia
and neural dysfunction. 8 In other lesions, mechanical
pressure on the neural tissue or a combination
of both traction and pressure is responsible
for neurological damage, which may be progressive
and irreversible in some cases. Although
earlier studies had suggested that early surgical
intervention may prevent neurological dysfunction
and improve long-term outcome in patients
with occult spinal dysraphism, these results have
been questioned by some recent studies. 8 However,
early detection and surgical excision of the
dorsal dermal sinus can prevent recurrent intraspinal
infection and its associated morbidity
and mortality.
EVALUATION
Although early detection and prompt neurosurgical
intervention in patients with occult spinal
dysraphism may be beneficial, it is equally important
to identify infants not at risk of associated
occult spinal dysraphism accurately to
avoid parental anxiety and indiscriminate use of
limited resources. Several studies have shown
that a simple dimple or coccygeal pit is not associated
with occult spinal dysraphism and no
workup is necessary in these infants. 3,5–7 These
studies have also reported that a combination of
two or more congenital midline skin lesions is
the strongest marker of occult spinal dysraphism.
However, the relative significance of
each cutaneous marker when present alone, has