HIRSCHSPRUNGS DISEASE
Category: Pediatric Surgery
Abstract : Hirschsprung's Disease : Hirschsprung's is the congenital absence of
parasympathetic innervation of the distal intestine. The colon proximal to the
aganglionic segment, in an effort to overcome the partial obstruction, becomes
distended and its wall markedly thickened because of muscle hypertrophy. Occurs
1 in 1000-1500 live births with a 4:1 male predominance. 96% are TAGA. 4%
premature
Hirschsprung's Disease : Hirschsprung's is the congenital absence of
parasympathetic innervation of the distal intestine. The colon proximal to the
aganglionic segment, in an effort to overcome the partial obstruction, becomes
distended and its wall markedly thickened because of muscle hypertrophy. Occurs
1 in 1000-1500 live births with a 4:1 male predominance. 96% are TAGA. 4%
prematures.
The parasympathetic ganglion cell network located between the
circular and longitudinal muscle layers
is referred to as Auerbach's plexus,
whereas Meissner's plexus is the submucosal layer of ganglion cells just beneath
the muscularis mucosa. In Hirschsprung's disease, ganglion cells are absent from
all layers. That aganglionic segment usually involves the terminal intestine,
i.e. the rectum or rectosigmoid. The aganglionic segment may, however, include
the entire large bowel and even small bowel.
Hirschsprung's disease (HD)
is characterized by lack of enteric ganglion cells, hyperplasia of
abnormal
nerve fibers and a non-propulsive, non-relaxing segment of bowel.
Classically the etiology is attributed to a failure of cranio-caudal migration
of parasympathetic neural crest cells to the distal bowel. A plausible
explanation for the failure of relaxation of the bowel involved is a deficiency
of enteric inhibitory nerves that mediates the relaxation phase of peristalsis.
This nerves are intrinsic to the gut and are classify as nonadrenergic and
non-cholinergic. Nitric oxide (NO) has recently been implicated as the
neurotransmitter which mediates the relaxation of smooth muscle of the GI tract
in HD. It's absence in aganglionic bowel might account for the failure of
relaxation during peristalsis. Besides, adhesions molecules (absent in
aganglionic bowel) during early embryogenesis might restrict the
neuro-ectodermal origin involved in the initial contact between nerves and
muscle cell (synaptogenesis) suggesting that developmental anomaly of innervated
muscle and absent NO causes the spasticity characteristic of HD.
Symptoms
usually begin at birth, frequently with delayed passage of meconium. Any newborn
who fails
to pass meconium in the first 24-48 hours of life should be
evaluated for possible Hirschsprung's disease. In some infants, the presentation
is that of complete intestinal obstruction. Others have relatively few symptoms
until several weeks of age, when the classic symptom of constipation has its
onset. Diarrhea is not uncommon but differs from the usual infantile diarrhea in
that it is associated with abdominal distension. Occasionally the patient will
go many years with mild constipation and diagnosis will be delayed.
The
diagnosis is first suspected based on history and physical examinations
(characteristically there
is no stool in rectum and abdominal distension is
painless). Initial evaluation includes an unprepared barium enema (the first
enema should be a barium enema!). The aganglionic rectum appears of normal
caliber or spastic, there is a transition zone and then dilated colon proximal
to the aganglionic segment. 24-hrs delayed films shows poor emptying with barium
throughout the colon, as opposed to the child with psychogenic stool holding in
whom the barium generally collects in the distal rectosigmoid. Rectal suction
biopsy is then performed. This can be done without anesthesia and the submucosal
plexus is examined for ganglion cells. With experience, a good pathologist
(should be an expert!), can identify the presence or absence of ganglion cells
in this specimen without a full thickness biopsy. Difficulty in interpreting the
specimen or not enough to include several slides of submucosa would require a
full-thickness biopsy for definitive diagnosis generally done under general
anesthesia. Some centers employ manometry, histochemical studies or special
stains for diagnosis. These special studies are only as good as the person
performing them and interpreting the results.
The initial treatment
requires performing a "leveling" colostomy in the most distal colon with
ganglion
cells present. This requires exploration with multiple seromuscular
biopsies of the colon wall to determine the exact extend of the aganglionosis.
The colostomy is placed above the transition zone. Placement of the colostomy in
an area of aganglionosis will lead to persistent obstruction. Once the child has
reached an adequate size and age (6-12 months; 20 pounds or more), a formal
pull-through procedure is done.
Some of this are: Swenson, Duhamel and
Soave procedures. Current preference is for Soave procedure (modified endorectal
pull-through) and consist of resection of the majority of aganglionic bowel
except for the most distal rectum, the mucosa and submucosa of this rectum is
excised and the normally innervated proximal bowel is pulled through the
seromuscular coat of retained rectum and suture immediately above the dentate
line. Recently a laparoscopic pull-through procedure avoiding the colostomy is
being used in early life with promising results.
Intestinal Neuronal
Dysplasia (IND) is a colonic motility disorder first described in 1971 by
Meier-Ruge
associated to characteristic histochemical changes of the bowel
wall (hyperplasia of submucous & myenteric plexus with giant ganglia
formation, isolated ganglion cells in lamina propria and muscularis mucosa,
elevation of acetylcholinesterase in parasympathetic fiber of lamina propria and
circular muscle, and myenteric plexus sympathetic hypoplastic innervation), also
known as hyperganglionosis associated to elevated acetylcholinesterase
parasympathetic staining. The condition can occur in an isolated form (either
localized to colon or disseminated throughout the bowel), or associated to other
diseases such as Hirschsprung's (HD), neurofibromatosis, MEN type IIB, and
anorectal malformations. It is estimated that 20-75% of HD cases have IND
changes proximal to the aganglionic segment.
Clinically two different
types of isolated IND have been described: Type A shows symptoms of abdominal
distension, enterocolitis, bloody stools, intestinal spasticity in imaging
studies (Ba Enema) since birth, is less common and associated with hypoplasia of
sympathetic nerves. Type B is more frequent, symptoms are indistinguishable from
that of HD, with chronic constipation, megacolon, and repeated episodes of bowel
obstruction. Management depends on clinical situation; conservative for minor
symptoms until neuronal maturation occurs around the 4th year of life, colostomy
and resectional therapy for life threatening situations.
Hit: 662 times
Related Articles in Pediatric Surgery :
|
Advertise with Health Information Encyclopedia