Dysphagia

Dysphagia is the sensation of difficulty in swallowing. Oropharyngeal, or transfer, dysphagia is the inability to initiate a swallow or propel food from the mouth to the esophagus. The hold-up occurs in the cervical area and is generally caused by a lesion affecting any level of the swallowing pathway rather than by a process affecting the oropharyngeal mucosa. Stroke and Parkinson disease are the neurologic disorders most commonly associated with oropharyngeal dysphagia, which may also occur in brainstem diseases (e.g., bulbar polio, Arnold–Chiari malformations, tumors) or muscle diseases such as dystrophies and mitochondrial cytopathies. Esophageal dysphagia is caused by abnormal esophageal peristalsis, more typically with smooth muscle disorders (e.g., progressive systemic sclerosis).

Neuromuscular dysphagia typically results in dysphagia to both liquids and solids, and aspiration into the upper airways.

Physical examination shows evidence of the coexisting neurologic disease, such as abnormal palatal or pharyngeal movements or a brisk jaw jerk, suggesting pseudo-bulbar palsy. Barium videofluoroscopy or a fiberoptic endoscopic evaluation of swallowing (FEES) can identify the motor and sensory disturbances, and may help stratify the risk of aspiration in patients with pharyngeal weakness. Pharyngoesophageal motility studies using solid-state pressure transducers also complement the diagnosis. Re-education of the swallowing process is feasible in many patients, often in a program that incorporates speech therapy. Nutritional support and prevention of bronchial aspiration are essential for those with more severe dysphagia not responding to conservative measures. This may require a gastrostomy feeding tube. Since swallowing may improve considerably in the first 2 weeks after a stroke, long-term decisions should be delayed for that period.

Gastroparesis

Gastric motor dysfunction resulting in delayed gastric emptying is a common gastrointestinal manifestation of autonomic neuropathies such as those associated with diabetes mellitus, surgical vagotomy (e.g., laparoscopic fundoplication), and numerous medications, most commonly narcotic analgesics, tricyclic antidepressants, and dopamine agonists. Symptoms range from vague postprandial abdominal discomfort to recurrent postprandial nausea, emesis, and bloating and pain resulting in weight loss and malnutrition. In diabetes mellitus, delayed gastric emptying is often asymptomatic. There may be a succussion splash on physical examination. It is essential to exclude gastric outlet obstruction by imaging the stomach or by endoscopy. Scintigraphic or stable isotope gastric emptying tests confirm delayed gastric emptying. Gastric stasis in neurologic diseases may result from abnormal motility of the stomach or small bowel; studies of pressure profiles by manometry or solid-state pressure transducers ( Fig. 14-3A ) are rarely required to differentiate neuropathic from myopathic processes ( Fig. 14-3B ), and exclude mechanical obstruction. Gastroparesis management guidelines have been updated, including the use of prokinetic agents, nutritional support, and interventions such as surgery and gastric electrical stimulation.

A , Tracing showing normal upper gastrointestinal motility in the fasting and fed states. The fasting tracing shows phase III of the interdigestive migrating motor complex. B , Manometric tracings showing the myopathic pattern of intestinal pseudo-obstruction due to systemic sclerosis ( left panel ) . Note the low amplitude of phasic pressure activity compared with control ( middle panel ) . A manometric example of neuropathic intestinal pseudo-obstruction in diabetes mellitus shows the absence of antral contractions and persistence of cyclical fasting-type motility in the postprandial period ( right panel ).

( A from Malagelada J-R, Camilleri M, Stanghellini V: Manometric Diagnosis of Gastrointestinal Motility Disorders. Thieme, New York, 1986, by permission of Mayo Foundation. B from Camilleri M: Medical treatment of chronic intestinal pseudo-obstruction. Pract Gastroenterol 15:10, 1991, with permission.)

Chronic Intestinal Pseudo-Obstruction

Chronic intestinal pseudo-obstruction is a syndrome characterized by nausea, vomiting, early satiety, abdominal discomfort, weight loss, and altered bowel movements suggestive of intestinal obstruction in the absence of a mechanical obstruction. These symptoms are the consequence of abnormal intestinal motility, including neurologic diseases extrinsic to the gut (e.g., disorders at any level of the neural axis), dysfunction of neurons in the myenteric plexus, or degeneration or malfunction of gut smooth muscle ( Table 14-1 ).

The patient’s accompanying clinical features may suggest an underlying disease process. Such features include postural dizziness, difficulties in visual accommodation in bright lights, sweating abnormalities, recurrent urinary infections, and problems with bladder voiding that suggest an autonomic neuropathy. Urinary manifestations are more commonly the result of pelvic floor dysfunction that accompanies constipation, independent of any neurologic disease. Examination should evaluate pupillary reflexes to light and accommodation, blood pressure and pulse in lying and standing positions, and abdominal distention or succussion splash.

The combination of external ophthalmoplegia, high dysphagia, peripheral neuromyopathy (e.g., increased serum creatine kinase) and acidosis (e.g., increased lactate, pyruvate) suggests mitochondrial cytopathy, a rare disorder associated with small bowel pseudo-obstruction and diverticulosis. Use of narcotics, phenothiazines, dopaminergic agents, antihypertensive agents such as clonidine, and tricyclic antidepressants having anticholinergic effects may cause intestinal dysmotility.

Plain radiographs and barium follow-through or computed tomographic (CT) or magnetic resonance (MR) enterography are often nonspecific; dilatation of the small intestine is more frequent in later stages of myopathic than neuropathic disorders. Motility studies ( Fig. 14-3 ) help differentiate myopathic and neuropathic processes. When a neuropathic process is identified, autonomic, radiologic and serologic tests should be performed to identify the cause of the autonomic neuropathy or cerebrospinal disease (see later).

The goals of treatment of chronic intestinal pseudo-obstruction include the restoration of hydration and nutrition, stimulation of normal intestinal propulsion, and suppression of bacterial overgrowth.

Constipation

Constipation is a common complaint and may be perceived by the patient as infrequent bowel movements, excessively hard stools, the need to strain excessively during defecation, or a sense of incomplete evacuation after defecation. The need for enemas or finger evacuation to expel the stool from the lower rectum suggests a disturbance of the pelvic floor or anorectum. The coexistence of incontinence and lack of rectal sensation suggests a neuropathy and is common among patients with diabetic neuropathy. The presence of blood in the stool with constipation necessitates further tests to exclude colonic mucosal lesions such as polyps, or perianal conditions such as hemorrhoids.

Broadly, constipation in neurologic disorders may be caused by potentially reversible factors (e.g., inadequate dietary fiber intake, lack of exercise, medications), slow colonic transit or pelvic floor dysfunction (i.e., a defecatory disorder) that may be related to the neurologic disorder, or another disease (e.g., colon cancer), or it may be a manifestation of functional disorder in patients who have a neurologic disease ( Fig. 14-4 ). Many neurologic diseases (e.g., Parkinson disease, multiple sclerosis, spinal cord injury, and autonomic neuropathies) can affect colonic transit and pelvic floor functions or lead to diminished rectal sensation (e.g., due to a neuropathy or spinal cord injury).

Schema showing normal alternations of pelvic floor, rectoanal angle, and sphincters during defecation.

(From Lembo T, Camilleri M: Chronic constipation. N Engl J Med 349:1360, 2003, with permission.)

The diagnosis and management of constipation in patients with neuromuscular disease include assessment of colonic anatomy, transit, and rectal evacuation. Slow colonic transit occurs frequently in wheelchair- or bed-bound patients and may require, in addition, stimulant cathartics or prokinetic medications and scheduled enemas daily or on alternate days. In patients with paraplegia, computer-assisted sacral anterior root stimulation has been used to evoke sigmoid and rectal contraction coordinated with sphincter relaxation, which resembles normal defecation. This procedure reduces the time for defecation and the interval between defecations. A dorsal rhizotomy must be performed to avoid general stimulation of autonomic responses. This treatment is available at specialized centers. An alternative treatment for colonic inertia (severe neuromuscular dysfunction with absent response to food ingestion or intravenous neostigmine) may be subtotal colectomy with ileorectostomy; however, if sphincter function is deficient and cannot be rehabilitated with physical therapy, a colostomy or ileostomy may be necessary. Other surgical procedures may correct a rectal prolapse or a rectocele.

Diarrhea

Diarrhea is defined as passage of abnormally liquid or unformed stools at an increased frequency, and is termed “chronic” if more than 4 weeks in duration. Acute diarrhea in neurologic patients is most frequently caused by infectious agents or medications. The differential diagnosis of chronic diarrhea is discussed in detail elsewhere. In autonomic neuropathies, as in patients with diabetic neuropathy, chronic diarrhea is often multifactorial and may be associated with intake of osmotic agents (e.g., artificial sweeteners), secretion, malabsorption secondary to rapid transit (possibly due to sympathetic denervation), small bowel bacterial overgrowth, bile acid diarrhea, and high-amplitude propulsive contractions in the colon that result in urgency and sometimes incontinence of stool.

Generally, the aid of a gastroenterologist is necessary to evaluate patients and guide diagnostic tests. Features of fat malabsorption (e.g., greasy, difficult-to-flush stools, weight loss) should prompt a 24- to 48-hour stool collection with quantitation of stool fat and, where available, total stool bile acids. The coexistence of diarrhea and neurologic manifestations may be explained by autonomic dysfunction (e.g., in diabetic neuropathy), the neurologic consequences of malabsorption (e.g., myopathy or neuropathy in celiac disease), and rare diseases with neurologic manifestations (e.g., Whipple disease). After excluding a structural cause (e.g., inflammatory bowel disease) and malabsorption, most patients with diarrhea due to disordered motility can be treated effectively with loperamide, beginning with 2 mg taken 30 minutes before meals, and titrated to control symptoms up to a maximum of 16 mg daily. Patients should be tested and treated for bacterial overgrowth. The α ₂ -adrenergic agonist clonidine reduces diarrhea by improving intestinal absorption, inhibiting intestinal and colonic motility, and enhancing resting anal sphincter tone; however, it aggravates postural hypotension, even when administered by transdermal patch. Other agents to be considered are oral bile acid sequestrants (e.g., cholestyramine and colesevelam) and subcutaneous octreotide.

Fecal Incontinence

Fecal incontinence may result from multiple sclerosis, Parkinson disease, multiple system atrophy, Alzheimer disease, stroke, diabetic neuropathy, and spinal cord lesions. In addition to generalized neuropathies (e.g., diabetes), obstetric trauma and stretch-induced pudendal nerve injury related to excessive straining in constipated patients are other causes of a pudendal neuropathy. Incontinence occurring only at night suggests internal anal sphincter dysfunction (e.g., progressive systemic sclerosis); stress incontinence during coughing, sneezing, or laughing suggests loss of external sphincter control, typically from pudendal nerve or S2, S3, and S4 root lesions. Leakage of formed stool suggests more severe sphincter weakness than leakage of liquid stool alone.

Examination of the incontinent patient should include inspection of the anus with and without straining to detect rectal prolapse, a digital rectal examination, and proctoscopy to exclude impaction or mucosal disease. Anal examination may disclose normal (e.g., multiple sclerosis) or reduced (e.g., diabetes mellitus, scleroderma) anal resting tone. The external sphincter and puborectalis contractile responses during squeeze are reduced, and the perianal wink reflex is absent in conditions affecting the lower spinal cord or pudendal nerves. Perineal weakness is often manifested by excessive perineal descent (>4 cm) on straining.

In evaluating such patients, it is important first to exclude overflow incontinence due to fecal impaction; overuse of laxatives or magnesium-containing antacids may result in reversible incontinence. If these are not identified as the cause of incontinence, further tests may be necessary: anorectal manometry, rectal sensation, ability to expel a balloon from the rectum, endoanal ultrasound or MRI to identify anal sphincter defects, and dynamic barium or MR defecography to identify rectal evacuation and anatomic abnormalities (e.g., rectocele, rectal intussusception). EMG of the anal sphincter is rarely required in patients with clinically suspected neurogenic sphincter weakness, particularly if there are features suggestive of proximal (i.e., sacral root) involvement; EMG provides evidence of denervation (fibrillation potentials), myopathic damage (small polyphasic motor unit potentials), neurogenic damage (large polyphasic motor unit potentials), or mixed injury. Pudendal neuropathy can be diagnosed with certainty when neurogenic changes affect anterior and posterior quadrants of the anal sphincter or they are also identified in the ischiocavernosus muscle.

Medical management includes perianal hygiene, protective devices to maintain skin integrity, and restoration of regular bowel habits. Biofeedback therapy has little impact in patients with weakness of the pelvic floor muscles or poor rectal sensation. Clonidine may help some patients, if it is tolerated. A colostomy may be necessary in patients with medically refractory fecal incontinence. Before resorting to this, it is important to exclude mucosal prolapse in association with incontinence, since surgical correction of the prolapse may temporarily improve continence by permitting better function of the external sphincter. More complex surgical procedures (i.e., artificial anal sphincter, dynamic graciloplasty) are not routinely performed in the United States. Sacral nerve stimulation can improve symptoms, anal pressures, and rectal sensation, even in patients with neurogenic fecal incontinence.

Brain Diseases

Autonomic System Degenerations

Spinal Cord Lesions

Peripheral Neuropathy