Superior mesenteric artery syndrome
Encyclopedia
Superior mesenteric artery (SMA) syndrome is a very rare
, life-threatening gastro-vascular
disorder characterized by a compression of the third portion of the duodenum
by the abdominal aorta
(AA) and the overlying superior mesenteric artery
. The syndrome is typically caused by an angle of 6°-25° between the AA and the SMA, in comparison to the normal range of 38°-56°, due to a lack of retroperitoneal and visceral fat. In addition, the aortomesenteric distance is 2-8 millimeters, as opposed to the typical 10-20.
SMA syndrome was first described in 1861 by Carl Freiherr von Rokitansky
in victims at autopsy, but remained pathologically undefined until 1927 when Wilkie published the first comprehensive series of 75 patients. Only 0.013 - 0.3% of upper-gastrointestinal-tract barium studies support a diagnosis, making it one of the rarest gastrointestinal disorders
known to medical science. With only about 500 reported cases in the history of English-language medical literature, recognition of SMA syndrome as a distinct clinical entity is controversial, with some in the medical community doubting its existence entirely. SMA syndrome is estimated to have a mortality rate of 1 in 3.
SMA syndrome is also known as Wilkie's syndrome, cast syndrome, mesenteric root syndrome, chronic duodenal ileus and intermittent arterio-mesenteric occlusion.
It is distinct from Nutcracker syndrome
, which is the entrapment of the left renal vein
between the AA and the SMA.
, vomiting
, extreme "stabbing" postprandial abdominal pain
(due to both the duodenal compression and the compensatory reversed peristalsis
), abdominal distention/distortion, eructation, external hypersensitivity or tenderness of the abdominal area, and severe malnutrition
accompanying spontaneous wasting
. This, in turn, increases the duodenal compression, spurring a vicious cycle. "Food fear" is a common development among patients with the chronic form of SMA syndrome. Symptoms are partially relieved when in the left lateral decubitus or knee-to-chest position. A Hayes maneuver (pressure applied below the umbilicus in cephalad and dorsal direction) elevates the root of the SMA, also slightly easing the constriction. Symptoms are often aggravated when leaning to the right or taking a supine
(face up) position.
fat and lymphatic tissue normally serve as a cushion for the duodenum, protecting it from compression by the SMA. SMA syndrome is thus triggered by any condition involving an insubstantial cushion and narrow mesenteric angle. SMA Syndrome can present in two forms: chronic/congenital or acute/induced.
Patients with the chronic, congenital form of SMA syndrome predominantly have a lengthy or even lifelong history of abdominal complaints with intermittent exacerbations depending on the degree of duodenal compression. Risk factors include anatomic characteristics such as: aesthenic (very thin or "lanky") body build, an unusually high insertion of the duodenum at the ligament of Treitz, a particularly low origin of the SMA, or intestinal malrotation
around an axis formed by the SMA. Predisposition is easily aggravated by any of the following: poor motility of the digestive tract, retroperitional tumors, loss of appetite
, malabsorption
, cachexia
, exaggerated lumbar lordosis
, visceroptosis
, abdominal wall laxity, peritoneal adhesions, abdominal trauma, rapid linear adolescent growth spurt, weight loss
, starvation
, and catabolic states (as with cancer
and burn
s).
The acute form of SMA Syndrome develops rapidly after traumatic incidents that forcibly hyper-extend the SMA across the duodenum, inducing the obstruction. Causes include prolonged supine bed rest (as with the application of body casts
), spinal cord injury
, scoliosis
, scoliosis surgery, or left nephrectomy.
As the syndrome involves a lack of essential fat, four of every five afflicted are underweight
, often to the point of sickliness and emaciation
. Females are impacted twice as often as males, with 75% of cases occurring between the ages of 10 and 30. Common co-morbid conditions include hyperchlorhydria
(noted in 50% of cases), peptic ulcer
disease (25-45%), pancreatitis
and scoliosis
.
Renowned American actor, director, producer, and writer Christopher Reeve
suffered from the acute form of SMA syndrome as a result of spinal cord injury
.
Delay in the diagnosis of SMA syndrome can result in fatal catabolysis
(advanced malnutrition
), dehydration
, oliguria
, electrolyte
abnormalities, hypokalemia
, acute gastric rupture or intestinal perforation (from prolonged mesenteric ischemia
), gastrectasia, spontaneous upper gastrointestinal bleeding
, hypovolemic shock, aspiration pneumonia
, or sudden cardiovascular collapse
(from increased velocity of bloodflow in the SMA due to the reduced mesenteric angle).
including upper endoscopy
, colonoscopy
, and evaluation for various malabsorptive, ulcerative and inflammatory instestinal conditions with a higher diagnostic frequency. Diagnosis may follow x-ray
examination revealing duodenal dilation followed by abrupt constriction proximal to the overlying SMA, as well as a delay in transit of four to six hours through the gastroduodenal region. Standard diagnostic exams include abdominal and pelvic computed tomography
(CT) scan with oral and IV contrast, upper gastrointestinal series (UGI), and, for equivocal cases, hypotonic duodenography. Once the diagnosis is made, vascular imaging studies such as ultrasound
and contrast angiography may be used to indicate increased bloodflow velocity through the SMA, signifying risk of sudden, fatal circulatory collapse
.
Despite multiple case reports, there has been controversy surrounding the diagnosis and even the existence of SMA syndrome since symptoms do not always correlate well with radiologic findings, and may not always improve following surgical correction. However, the reason for the persistance of gastrointestinal symptoms even after surgical correction has been recently traced to the remaining prominence of reversed peristalsis
in contrast to direct peristalsis.
Since females between the ages of 10 and 30 are most frequently afflicted, it is not uncommon for physicians to initially and incorrectly assume that emaciation
is a choice of the patient instead of a consequence of SMA syndrome in its chronic form. Patients in the earlier stages of chronic SMA syndrome often remain unaware that they are ill until substantial damage to their health is done, since they may attempt to adapt to the condition by gradually decreasing their food intake or naturally gravitating toward a lighter and more digestible diet. Eating disorder
treatment protocols involving forced refeeding and behavioral therapy are noted to have poor outcomes with individuals suffering from SMA syndrome, contributing to the high mortality rate of the condition.
, acquired form (i.e. abruptly emerging within an inpatient stay following scoliosis surgery) as well as chronic
form (i.e. developing throughout the course of a lifetime and advancing due to environmental triggers, life changes, or other illnesses). Acute cases usually respond to medical management, while chronic cases require surgical intervention.
In acute or mild cases, conservative treatment should be attempted first, involving the reversal or removal of the precipitating factor with proper nutrition
and replacement of fluid and electrolytes, either by surgically-inserted jejunal feeding tube
, nasogastric intubation
, or peripherally inserted central catheter
(PICC line) administering total parenteral nutrition
(TPN). Pro-motility agents such as metoclopramide
may also be beneficial. Symptoms typically improve after restoration of weight, except when reversed peristalsis persists, or if regained fat refuses to accumulate within the mesenteric angle.
If conservative treatment fails, or if the case is severe or chronic, surgical intervention is required. The most common operation for SMA syndrome, duodenojejunostomy, was first proposed in 1907 by Bloodgood. Performed as either an open surgery or laparoscopically, duodenojejunostomy involves the creation of an anastomosis between the duodenum
and the jejunum
, bypassing the compression caused by the AA and the SMA. Less common surgical treatments for SMA syndrome include Roux-en-Y duodenojejunostomy, gastrojejunostomy, anterior transposition of the third portion of the duodenum, intestinal derotation, and division of the ligament of Treitz. Lysis of the duodenal suspensory muscle has the advantage that it does not involve the creation of an intestinal anastomosis.
The world's first robotically-assisted intestinal bypass for SMA syndrome was performed on July 30, 2008 at the London Health Sciences Centre in Ontario, Canada. In contrast to traditional open duodenojejunostomy which involves a 15-centimeter scar on the upper belly, inelastic internal staples, a one-week hospital stay and significant postoperative pain, the Da Vinci robot's range of motion allows for the use of stitches in place of staples, minimizes scarring to only five one-centimeter incisions and reduces both hospital recovery time and narcotic use by more than 50%.
The possible persistence of symptoms after surgical bypass can be traced to the remaining prominence of reversed peristalsis
in contrast to direct peristalsis, although the precipitating factor (the duodenal compression) has been bypassed or relieved. Reversed peristalsis has been shown to respond to duodenal circular drainage—a complex and invasive open surgical procedure originally implemented and performed in China.
Rare disease
A rare disease, also referred to as an orphan disease, is any disease that affects a small percentage of the population.Most rare diseases are genetic, and thus are present throughout the person's entire life, even if symptoms do not immediately appear...
, life-threatening gastro-vascular
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...
disorder characterized by a compression of the third portion of the duodenum
Duodenum
The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms anterior intestine or proximal intestine may be used instead of duodenum...
by the abdominal aorta
Abdominal aorta
The abdominal aorta is the largest artery in the abdominal cavity. As part of the aorta, it is a direct continuation of the descending aorta .-Path:...
(AA) and the overlying superior mesenteric artery
Superior mesenteric artery
In human anatomy, the superior mesenteric artery arises from the anterior surface of the abdominal aorta, just inferior to the origin of the celiac trunk, and supplies the intestine from the lower part of the duodenum through two-thirds of the transverse colon, as well as the pancreas.-Location...
. The syndrome is typically caused by an angle of 6°-25° between the AA and the SMA, in comparison to the normal range of 38°-56°, due to a lack of retroperitoneal and visceral fat. In addition, the aortomesenteric distance is 2-8 millimeters, as opposed to the typical 10-20.
SMA syndrome was first described in 1861 by Carl Freiherr von Rokitansky
Carl Freiherr von Rokitansky
Baron Carl von Rokitansky , was a Bohemian physician, pathologist, humanist philosopher and liberal politician.-Medical career:...
in victims at autopsy, but remained pathologically undefined until 1927 when Wilkie published the first comprehensive series of 75 patients. Only 0.013 - 0.3% of upper-gastrointestinal-tract barium studies support a diagnosis, making it one of the rarest gastrointestinal disorders
Rare disease
A rare disease, also referred to as an orphan disease, is any disease that affects a small percentage of the population.Most rare diseases are genetic, and thus are present throughout the person's entire life, even if symptoms do not immediately appear...
known to medical science. With only about 500 reported cases in the history of English-language medical literature, recognition of SMA syndrome as a distinct clinical entity is controversial, with some in the medical community doubting its existence entirely. SMA syndrome is estimated to have a mortality rate of 1 in 3.
SMA syndrome is also known as Wilkie's syndrome, cast syndrome, mesenteric root syndrome, chronic duodenal ileus and intermittent arterio-mesenteric occlusion.
It is distinct from Nutcracker syndrome
Nutcracker syndrome
In medicine, the nutcracker syndrome — is a clinically manifest variant of nutcracker phenomenon, renal vein entrapment syndrome, or mesoaortic compression of the left renal vein. It results most commonly from the compression of the left renal vein between the abdominal aorta and superior...
, which is the entrapment of the left renal vein
Renal vein
The renal veins are veins that drain the kidney. They connect the kidney to the inferior vena cava.It is usually singular to each kidney, except in the condition "multiple renal veins".It also divides into 2 divisions upon entering the kidney:...
between the AA and the SMA.
Symptoms
Symptoms include early satiety, nauseaNausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...
, vomiting
Vomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...
, extreme "stabbing" postprandial abdominal pain
Abdominal pain
Abdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem...
(due to both the duodenal compression and the compensatory reversed peristalsis
Peristalsis
Peristalsis is a radially symmetrical contraction and relaxation of muscles which propagates in a wave down the muscular tube, in an anterograde fashion. In humans, peristalsis is found in the contraction of smooth muscles to propel contents through the digestive tract. Earthworms use a similar...
), abdominal distention/distortion, eructation, external hypersensitivity or tenderness of the abdominal area, and severe malnutrition
Malnutrition
Malnutrition is the condition that results from taking an unbalanced diet in which certain nutrients are lacking, in excess , or in the wrong proportions....
accompanying spontaneous wasting
Wasting
In medicine, wasting refers to the process by which a debilitating disease causes muscle and fat tissue to "waste" away. Wasting is sometimes referred to as "acute malnutrition" because it is believed that episodes of wasting have a short duration, in contrast to stunting, which is regarded as...
. This, in turn, increases the duodenal compression, spurring a vicious cycle. "Food fear" is a common development among patients with the chronic form of SMA syndrome. Symptoms are partially relieved when in the left lateral decubitus or knee-to-chest position. A Hayes maneuver (pressure applied below the umbilicus in cephalad and dorsal direction) elevates the root of the SMA, also slightly easing the constriction. Symptoms are often aggravated when leaning to the right or taking a supine
Supine position
The supine position is a position of the body: lying down with the face up, as opposed to the prone position, which is face down, sometimes with the hands behind the head or neck. When used in surgical procedures, it allows access to the peritoneal, thoracic and pericardial regions; as well as the...
(face up) position.
Causes
RetroperitonealRetroperitoneum
The retroperitoneal space is the anatomical space in the abdominal cavity behind the peritoneum. It has no specific delineating anatomical structures...
fat and lymphatic tissue normally serve as a cushion for the duodenum, protecting it from compression by the SMA. SMA syndrome is thus triggered by any condition involving an insubstantial cushion and narrow mesenteric angle. SMA Syndrome can present in two forms: chronic/congenital or acute/induced.
Patients with the chronic, congenital form of SMA syndrome predominantly have a lengthy or even lifelong history of abdominal complaints with intermittent exacerbations depending on the degree of duodenal compression. Risk factors include anatomic characteristics such as: aesthenic (very thin or "lanky") body build, an unusually high insertion of the duodenum at the ligament of Treitz, a particularly low origin of the SMA, or intestinal malrotation
Intestinal malrotation
Intestinal malrotation is a congenital anomaly of rotation of the midgut...
around an axis formed by the SMA. Predisposition is easily aggravated by any of the following: poor motility of the digestive tract, retroperitional tumors, loss of appetite
Anorexia (symptom)
Anorexia is the decreased sensation of appetite...
, malabsorption
Malabsorption
Malabsorption is a state arising from abnormality in absorption of food nutrients across the gastrointestinal tract.Impairment can be of single or multiple nutrients depending on the abnormality...
, cachexia
Cachexia
Cachexia or wasting syndrome is loss of weight, muscle atrophy, fatigue, weakness, and significant loss of appetite in someone who is not actively trying to lose weight...
, exaggerated lumbar lordosis
Lordosis
Lordosis is a medical term used to describe an inward curvature of a portion of the lumbar and cervical vertebral column. Two segments of the vertebral column, namely cervical and lumbar, are normally lordotic, that is, they are set in a curve that has its convexity anteriorly and concavity...
, visceroptosis
Visceroptosis
Visceroptosis is a prolapse or a sinking of the abdominal viscera below their natural position. Any or all of the organs may be displaced downward. When the intestines are involved, the condition is known as enteroptosis; when the stomach is found below its normal position, the term...
, abdominal wall laxity, peritoneal adhesions, abdominal trauma, rapid linear adolescent growth spurt, weight loss
Weight loss
Weight loss, in the context of medicine, health or physical fitness, is a reduction of the total body mass, due to a mean loss of fluid, body fat or adipose tissue and/or lean mass, namely bone mineral deposits, muscle, tendon and other connective tissue...
, starvation
Starvation
Starvation is a severe deficiency in caloric energy, nutrient and vitamin intake. It is the most extreme form of malnutrition. In humans, prolonged starvation can cause permanent organ damage and eventually, death...
, and catabolic states (as with cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
and burn
Burn
A burn is an injury to flesh caused by heat, electricity, chemicals, light, radiation, or friction.Burn may also refer to:*Combustion*Burn , type of watercourses so named in Scotland and north-eastern England...
s).
The acute form of SMA Syndrome develops rapidly after traumatic incidents that forcibly hyper-extend the SMA across the duodenum, inducing the obstruction. Causes include prolonged supine bed rest (as with the application of body casts
Orthopedic cast
An orthopedic cast, body cast or surgical cast, is a shell, frequently made from plaster, encasing a limb to hold a broken bone in place until healing is confirmed...
), spinal cord injury
Spinal cord injury
A spinal cord injury refers to any injury to the spinal cord that is caused by trauma instead of disease. Depending on where the spinal cord and nerve roots are damaged, the symptoms can vary widely, from pain to paralysis to incontinence...
, scoliosis
Scoliosis
Scoliosis is a medical condition in which a person's spine is curved from side to side. Although it is a complex three-dimensional deformity, on an X-ray, viewed from the rear, the spine of an individual with scoliosis may look more like an "S" or a "C" than a straight line...
, scoliosis surgery, or left nephrectomy.
Demographics
SMA syndrome is extremely rare, evident in only 0.013 - 0.3% of upper-gastrointestinal-tract barium studies. However, unfamiliarity with this condition in the medical community coupled with its intermittent and nonspecific symptomatology probably results in its underdiagnosis.As the syndrome involves a lack of essential fat, four of every five afflicted are underweight
Underweight
The term underweight refers to a human who is considered to be under a healthy weight. "Underweight" means weighing less than what is expected to be a healthy person . The definition is usually made with reference to the body mass index . A BMI of under 18.5 is usually referred to as underweight...
, often to the point of sickliness and emaciation
Emaciation
Emaciation occurs when an organism loses substantial amounts of much needed fat and often muscle tissue, making that organism look extremely thin. The cause of emaciation is a lack of nutrients, starvation, or disease....
. Females are impacted twice as often as males, with 75% of cases occurring between the ages of 10 and 30. Common co-morbid conditions include hyperchlorhydria
Hyperchlorhydria
Hyperchlorhydria refers to the state in the stomach where gastric acid levels are higher than the normal range. In humans, the normal pH is around 1 to 3, which varies throughout the day. The highest basal secretion levels are in the late evening . Hyperchlorhydria is usually defined as having a...
(noted in 50% of cases), peptic ulcer
Peptic ulcer
A peptic ulcer, also known as PUD or peptic ulcer disease, is the most common ulcer of an area of the gastrointestinal tract that is usually acidic and thus extremely painful. It is defined as mucosal erosions equal to or greater than 0.5 cm...
disease (25-45%), pancreatitis
Pancreatitis
Pancreatitis is inflammation of the pancreas. It occurs when pancreatic enzymes that digest food are activated in the pancreas instead of the small intestine. It may be acute – beginning suddenly and lasting a few days, or chronic – occurring over many years...
and scoliosis
Scoliosis
Scoliosis is a medical condition in which a person's spine is curved from side to side. Although it is a complex three-dimensional deformity, on an X-ray, viewed from the rear, the spine of an individual with scoliosis may look more like an "S" or a "C" than a straight line...
.
Renowned American actor, director, producer, and writer Christopher Reeve
Christopher Reeve
Christopher D'Olier Reeve was an American actor, film director, producer, screenwriter, author and activist...
suffered from the acute form of SMA syndrome as a result of spinal cord injury
Spinal cord injury
A spinal cord injury refers to any injury to the spinal cord that is caused by trauma instead of disease. Depending on where the spinal cord and nerve roots are damaged, the symptoms can vary widely, from pain to paralysis to incontinence...
.
Mortality
SMA syndrome is estimated to have a mortality rate of 1 in 3.Delay in the diagnosis of SMA syndrome can result in fatal catabolysis
Catabolysis
Catabolysis is a biological process in which the body breaks down fat and muscle tissue in order to stay alive. Catabolysis occurs only when there is no longer any source of protein, carbohydrate, or vitamin nourishment feeding all body systems; it is the most severe type of malnutrition.- Disease...
(advanced malnutrition
Malnutrition
Malnutrition is the condition that results from taking an unbalanced diet in which certain nutrients are lacking, in excess , or in the wrong proportions....
), dehydration
Dehydration
In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...
, oliguria
Oliguria
Oliguria is the low output of urine, It is clinically classified as an output below 300-500ml/day. The decreased output of urine may be a sign of dehydration, renal failure, hypovolemic shock, HHNS Hyperosmolar Hyperglycemic Nonketotic Syndrome, multiple organ dysfunction syndrome, urinary...
, electrolyte
Electrolyte
In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....
abnormalities, hypokalemia
Hypokalemia
Hypokalemia or hypokalaemia , also hypopotassemia or hypopotassaemia , refers to the condition in which the concentration of potassium in the blood is low...
, acute gastric rupture or intestinal perforation (from prolonged mesenteric ischemia
Mesenteric ischemia
Mesenteric ischemia is a medical condition in which inflammation and injury of the small intestine result from inadequate blood supply. Causes of the reduced blood flow can include changes in the systemic circulation or local factors such as constriction of blood vessels or a blood clot...
), gastrectasia, spontaneous upper gastrointestinal bleeding
Upper gastrointestinal bleeding
Upper gastrointestinal bleeding refers to hemorrhage in the upper gastrointestinal tract. The anatomic cut-off for upper GI bleeding is the ligament of Treitz, which connects the fourth portion of the duodenum to the diaphragm near the splenic flexure of the colon.Upper GI bleeds are considered...
, hypovolemic shock, aspiration pneumonia
Aspiration pneumonia
Aspiration pneumonia is bronchopneumonia that develops due to the entrance of foreign materials into the bronchial tree, usually oral or gastric contents...
, or sudden cardiovascular collapse
Circulatory collapse
A circulatory collapse is defined as a general or specific failure of the circulation, either cardiac or peripheral in nature. A common cause of this could be shock or trauma from injury or surgery...
(from increased velocity of bloodflow in the SMA due to the reduced mesenteric angle).
Diagnosis
Diagnosis is very difficult, and usually one of exclusion. SMA syndrome is thus considered only after patients have undergone an extensive evaluation of their gastrointestinal tractGastrointestinal tract
The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....
including upper endoscopy
Esophagogastroduodenoscopy
For other expansions of the initialism "OGD", see the disambiguation page.In medicine , esophagogastroduodenoscopy is a diagnostic endoscopic procedure that visualizes the upper part of the gastrointestinal tract up to the duodenum...
, colonoscopy
Colonoscopy
Colonoscopy is the endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus. It may provide a visual diagnosis and grants the opportunity for biopsy or removal of suspected...
, and evaluation for various malabsorptive, ulcerative and inflammatory instestinal conditions with a higher diagnostic frequency. Diagnosis may follow x-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
examination revealing duodenal dilation followed by abrupt constriction proximal to the overlying SMA, as well as a delay in transit of four to six hours through the gastroduodenal region. Standard diagnostic exams include abdominal and pelvic computed tomography
Computed tomography
X-ray computed tomography or Computer tomography , is a medical imaging method employing tomography created by computer processing...
(CT) scan with oral and IV contrast, upper gastrointestinal series (UGI), and, for equivocal cases, hypotonic duodenography. Once the diagnosis is made, vascular imaging studies such as ultrasound
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
and contrast angiography may be used to indicate increased bloodflow velocity through the SMA, signifying risk of sudden, fatal circulatory collapse
Circulatory collapse
A circulatory collapse is defined as a general or specific failure of the circulation, either cardiac or peripheral in nature. A common cause of this could be shock or trauma from injury or surgery...
.
Despite multiple case reports, there has been controversy surrounding the diagnosis and even the existence of SMA syndrome since symptoms do not always correlate well with radiologic findings, and may not always improve following surgical correction. However, the reason for the persistance of gastrointestinal symptoms even after surgical correction has been recently traced to the remaining prominence of reversed peristalsis
Peristalsis
Peristalsis is a radially symmetrical contraction and relaxation of muscles which propagates in a wave down the muscular tube, in an anterograde fashion. In humans, peristalsis is found in the contraction of smooth muscles to propel contents through the digestive tract. Earthworms use a similar...
in contrast to direct peristalsis.
Since females between the ages of 10 and 30 are most frequently afflicted, it is not uncommon for physicians to initially and incorrectly assume that emaciation
Emaciation
Emaciation occurs when an organism loses substantial amounts of much needed fat and often muscle tissue, making that organism look extremely thin. The cause of emaciation is a lack of nutrients, starvation, or disease....
is a choice of the patient instead of a consequence of SMA syndrome in its chronic form. Patients in the earlier stages of chronic SMA syndrome often remain unaware that they are ill until substantial damage to their health is done, since they may attempt to adapt to the condition by gradually decreasing their food intake or naturally gravitating toward a lighter and more digestible diet. Eating disorder
Eating disorder
Eating disorders refer to a group of conditions defined by abnormal eating habits that may involve either insufficient or excessive food intake to the detriment of an individual's physical and mental health. Bulimia nervosa, anorexia nervosa, and binge eating disorder are the most common specific...
treatment protocols involving forced refeeding and behavioral therapy are noted to have poor outcomes with individuals suffering from SMA syndrome, contributing to the high mortality rate of the condition.
Treatment
SMA syndrome can present in acuteAcute (medicine)
In medicine, an acute disease is a disease with either or both of:# a rapid onset, as in acute infection# a short course ....
, acquired form (i.e. abruptly emerging within an inpatient stay following scoliosis surgery) as well as chronic
Chronic (medicine)
A chronic disease is a disease or other human health condition that is persistent or long-lasting in nature. The term chronic is usually applied when the course of the disease lasts for more than three months. Common chronic diseases include asthma, cancer, diabetes and HIV/AIDS.In medicine, the...
form (i.e. developing throughout the course of a lifetime and advancing due to environmental triggers, life changes, or other illnesses). Acute cases usually respond to medical management, while chronic cases require surgical intervention.
In acute or mild cases, conservative treatment should be attempted first, involving the reversal or removal of the precipitating factor with proper nutrition
Nutrition
Nutrition is the provision, to cells and organisms, of the materials necessary to support life. Many common health problems can be prevented or alleviated with a healthy diet....
and replacement of fluid and electrolytes, either by surgically-inserted jejunal feeding tube
Feeding tube
A feeding tube is a medical device used to provide nutrition to patients who cannot obtain nutrition by swallowing. The state of being fed by a feeding tube is called gavage, enteral feeding or tube feeding...
, nasogastric intubation
Nasogastric intubation
Nasogastric intubation is a medical process involving the insertion of a plastic tube through the nose, past the throat, and down into the stomach.-Uses:...
, or peripherally inserted central catheter
Peripherally inserted central catheter
A peripherally inserted central catheter is a form of intravenous access that can be used for a prolonged period of time...
(PICC line) administering total parenteral nutrition
Total parenteral nutrition
Parenteral nutrition is feeding a person intravenously, bypassing the usual process of eating and digestion. The person receives nutritional formulae that contain nutrients such as glucose, amino acids, lipids and added vitamins and dietary minerals...
(TPN). Pro-motility agents such as metoclopramide
Metoclopramide
Metoclopramide is an antiemetic and gastroprokinetic agent. It is commonly used to treat nausea and vomiting, to facilitate gastric emptying in people with gastroparesis, and as a treatment for the gastric stasis often associated with migraine headaches.-Medical uses:Metoclopramide is commonly...
may also be beneficial. Symptoms typically improve after restoration of weight, except when reversed peristalsis persists, or if regained fat refuses to accumulate within the mesenteric angle.
If conservative treatment fails, or if the case is severe or chronic, surgical intervention is required. The most common operation for SMA syndrome, duodenojejunostomy, was first proposed in 1907 by Bloodgood. Performed as either an open surgery or laparoscopically, duodenojejunostomy involves the creation of an anastomosis between the duodenum
Duodenum
The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms anterior intestine or proximal intestine may be used instead of duodenum...
and the jejunum
Jejunum
The jejunum is the middle section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms middle intestine or mid-gut may be used instead of jejunum.The jejunum lies between the duodenum...
, bypassing the compression caused by the AA and the SMA. Less common surgical treatments for SMA syndrome include Roux-en-Y duodenojejunostomy, gastrojejunostomy, anterior transposition of the third portion of the duodenum, intestinal derotation, and division of the ligament of Treitz. Lysis of the duodenal suspensory muscle has the advantage that it does not involve the creation of an intestinal anastomosis.
The world's first robotically-assisted intestinal bypass for SMA syndrome was performed on July 30, 2008 at the London Health Sciences Centre in Ontario, Canada. In contrast to traditional open duodenojejunostomy which involves a 15-centimeter scar on the upper belly, inelastic internal staples, a one-week hospital stay and significant postoperative pain, the Da Vinci robot's range of motion allows for the use of stitches in place of staples, minimizes scarring to only five one-centimeter incisions and reduces both hospital recovery time and narcotic use by more than 50%.
The possible persistence of symptoms after surgical bypass can be traced to the remaining prominence of reversed peristalsis
Peristalsis
Peristalsis is a radially symmetrical contraction and relaxation of muscles which propagates in a wave down the muscular tube, in an anterograde fashion. In humans, peristalsis is found in the contraction of smooth muscles to propel contents through the digestive tract. Earthworms use a similar...
in contrast to direct peristalsis, although the precipitating factor (the duodenal compression) has been bypassed or relieved. Reversed peristalsis has been shown to respond to duodenal circular drainage—a complex and invasive open surgical procedure originally implemented and performed in China.
See also
- CatabolysisCatabolysisCatabolysis is a biological process in which the body breaks down fat and muscle tissue in order to stay alive. Catabolysis occurs only when there is no longer any source of protein, carbohydrate, or vitamin nourishment feeding all body systems; it is the most severe type of malnutrition.- Disease...
- MalnutritionMalnutritionMalnutrition is the condition that results from taking an unbalanced diet in which certain nutrients are lacking, in excess , or in the wrong proportions....
- Medical emergencyMedical emergencyA medical emergency is an injury or illness that is acute and poses an immediate risk to a person's life or long term health. These emergencies may require assistance from another person, who should ideally be suitably qualified to do so, although some of these emergencies can be dealt with by the...
- Median arcuate ligament syndromeMedian arcuate ligament syndromeIn medicine, the median arcuate ligament syndrome is a condition characterized by abdominal pain attributed to compression of the celiac artery and possibly the celiac ganglia by the median arcuate ligament. The abdominal pain may be related to meals, may be accompanied by weight loss, and may be...
- Nutcracker syndromeNutcracker syndromeIn medicine, the nutcracker syndrome — is a clinically manifest variant of nutcracker phenomenon, renal vein entrapment syndrome, or mesoaortic compression of the left renal vein. It results most commonly from the compression of the left renal vein between the abdominal aorta and superior...
- Small bowel obstruction
- Rare diseases
- VisceroptosisVisceroptosisVisceroptosis is a prolapse or a sinking of the abdominal viscera below their natural position. Any or all of the organs may be displaced downward. When the intestines are involved, the condition is known as enteroptosis; when the stomach is found below its normal position, the term...
- WastingWastingIn medicine, wasting refers to the process by which a debilitating disease causes muscle and fat tissue to "waste" away. Wasting is sometimes referred to as "acute malnutrition" because it is believed that episodes of wasting have a short duration, in contrast to stunting, which is regarded as...