Specific motor disorders a
Esophageal outflow obstruction
Achalasia, subtypes 1, 2, and 3
Esophagogastric junction outflow obstruction: motor or structural
Major motor disorders
Hypercontractile disorder (jackhammer esophagus)
Diffuse esophageal spasm
Minor motor disorders
Ineffective esophageal motility
Nonspecific motor disorders
Esophageal body disorders
Contraction wave abnormalities
High contraction amplitudes
Double and multiple peaked waves
Rapid or simultaneous contractions
Broad peristaltic wave duration
Distal shift in contraction vigor
Breaks in peristaltic integrity
Abnormal EGJ morphology: hiatus hernia
Other nonspecific disorders
High-resolution manometry (HRM) has allowed improved identification, understanding, and management of motor disorders of the esophagus and anorectum [1, 4, 5]. HRM data is displayed in a three-dimensional topographic “Clouse plot ” of time, distance, and pressure representation as a color scale. With the initial reports of HRM in normal volunteers, it became evident that esophageal peristalsis relies on contracting segments, the proximal skeletal muscle segment (segment 1), and the distal two smooth muscle contraction segments (segments 2 and 3) . Peristalsis is therefore visualized as a chain of contracting segments and relaxing sphincters, assessed using measurements of smooth muscle contraction vigor (distal contractile integral, DCI), peristaltic timing (distal latency, DL), and nadir residual pressures at the esophagogastric junction during swallows (integrated relaxation pressure, IRP) [1, 7, 8]. Changes in individual contraction segments can result in motor abnormalities, and the most profound of these are identified within the Chicago Classification v. 3.0  (Table 4.1). A progressive gradient of decreasing cholinergic and increasing non-cholinergic, non-adrenergic influence in smooth muscle segments has been reported in animal models, and this is supported by observing the cholinergic effects of cisapride in enhancing more cephalad smooth muscle contraction [10, 11]. Therefore, many of the esophageal body motor disorders can be explained on the basis of incomplete contractile function (with cholinergic neurotransmission), or abnormal esophageal inhibition (where non-cholinergic, non-adrenergic influences dominate, mediated by nitric oxide).
With HRM, achalasia diagnosis has become more precise and detailed, with three achalasia subtypes now recognized . Abnormal relaxation of the lower esophageal sphincter (LES) remains the hallmark for the diagnosis of achalasia, now identified when the IRP is elevated above the upper limit of normal for the particular HRM system being utilized. Incomplete achalasia patterns with retained esophageal body peristalsis have been characterized (EGJ outflow obstruction), which need to be differentiated from structural mechanical processes at the EGJ with alternate complementary tests . Diffuse esophageal spasm is now diagnosed based on a shortened latency (DL < 4.5 s) between initiation of the swallow (relaxation of the upper esophageal sphincter or UES) and the arrival of the contraction sequence in the distal esophagus. Esophageal body contraction vigor, assessed using DCI, is further characterized into ineffective (DCI < 450 mm Hg cm s) and hypercontractile peristalsis (DCI > 8000 mm Hg cm s); DCI also defines a failed sequence (DCI < 100 mm Hg cm s) from a weak sequence within the ineffective realm. Motor patterns not meeting the criteria for esophageal outflow obstruction (achalasia spectrum, mechanical EGJ obstruction), major motor disorders (diffuse esophageal spasm, hypercontractile disorder, absent contractility), and minor motor disorders (ineffective esophageal motility, fragmented peristalsis) are considered normal.
What Are Nonspecific Motor Disorders and Why Do They Develop?
In the current HRM era, motor disorders are therefore specific. However, abnormal contraction wave patterns exist within the “normal” realm that do not fulfil the criteria for a named HRM abnormality, but are nevertheless abnormal patterns. Many of these have origins within conventional manometry, with abnormalities in peristaltic wave pattern (double and multiple peaked waves), wave duration, propagation velocity, and wave amplitude (Table 4.1). Others have evolved from HRM, especially breaks in the peristaltic contour. Abnormal sphincter metrics are not defined within the HRM classifications of motor disorders, and could be considered nonspecific abnormalities. Finally, motor abnormalities have also been described with rumination and supragastric belching.
Contraction Wave Abnormalities
Normal smooth muscle contraction in the esophagus requires a balance between excitatory and inhibitory influences on esophageal motor function . When control of smooth muscle contraction is abnormal, the contraction wave can be premature, non-peristaltic, and exaggerated (Fig. 4.1). The duration of the contraction wave can be prolonged, and the contraction at individual amplitudes can be double peaked or multiple peaked . The correlate for multiple peaked waves on HRM consists of overlapping smooth muscle contraction segments (Fig. 4.1), rather than the normal sequential segmental architecture where the third contraction segment follows the second segment . Using balloon distension in conjunction with pressure measurements, Sifrim et al. demonstrated abnormal esophageal inhibition in patients with contraction wave abnormalities (CWA) and simultaneous contractions fulfilling criteria for diffuse esophageal spasm (DES) . In these studies, there was an inverse relationship between the degree of inhibition and the propagation velocity of deglutitive contraction, as well as an absence of inhibition in simultaneous contractions . With HRM, however, individual smooth muscle contraction segments are not separately evaluated; instead, vigor of the entire smooth muscle contraction is evaluated using DCI, thereby overriding specific contraction abnormalities to obtain an overview of adequacy of smooth muscle contraction . Similarly, timing of peristalsis is assessed using DL, which measures timing of contraction in relationship to initiation of peristalsis, but does not assess simultaneity in the smooth muscle contraction . Use of these two HRM metrics identifies motor disorders that are well developed (i.e., hypercontractile disorder, diffuse esophageal spasm), but may miss individual contraction wave abnormalities (CWA) if DCI or DL is normal .
Contraction wave abnormalities with normal Chicago Classification parameters. In all instances, distal contractile integral (DCI) and distal latency (DL) were within normal limits described for these parameters. (a) Normal esophageal body peristaltic sequence for comparison purposes. (b) Broad duration of the peristaltic sequence, >5.7 s. (c) Rapid contraction sequence, with normal DL. (d) Double-peaked peristaltic sequence, with overlapping third contraction segment. (e) Multiple peaked peristaltic sequence, with multiple repetitive contraction of the third contraction segment. (f) Exaggerated contraction vigor in the third segment
There is increasing evidence suggesting a relationship between esophageal perception and CWA. For instance, Borjesson et al. demonstrated using intraesophageal balloon distension that increased visceral perception (i.e., lowered thresholds for esophageal pain perception) correlated with higher amplitude and duration of esophageal peristaltic waves . Further evidence for increased esophageal perception is provided by the fact that patients with these nonspecific changes in the contraction wave are more likely to have residual perceptive esophageal symptoms such as heartburn, and an increased need for medication usage following adequate antireflux therapy, when compared with patients without these abnormalities . There is a higher likelihood of acid sensitivity (where esophageal acid exposure time is physiologic, but a statistical correlation is identified between symptoms and reflux events) in patients with exaggerated contraction patterns in the esophageal smooth muscle .
Provocative study of nonobstructive dysphagia and noncardiac chest pain has provided insights into the relevance of contraction wave abnormalities. Some CWA can be induced by provocative balloon testing in patients with nonobstructive dysphagia [21, 22]. While normal volunteers are not symptomatic and only develop secondary peristalsis during sustained balloon distension in the esophagus, patients with nonobstructive dysphagia develop simultaneous contractions and other CWA during balloon distension, and the majority develop their characteristic symptom [21, 23]. Further, automated impedance manometry (AIM) analysis has suggested that nadir esophageal impedance (indicating peak bolus content) is closer to peak contraction pressures with nonobstructive dysphagia in contrast to healthy controls, where nadir impedance and peak contraction are further apart . While the exact pathophysiology is not known, asynchrony between contraction of the esophageal circular and longitudinal muscles may explain these findings. This has been demonstrated in patients with noncardiac chest pain, which could provide insights into how CWA might be associated with perceptive symptoms. In a normal patient, circular muscle contraction, as assessed by increase in intraluminal pressure, is synchronized with longitudinal muscle contraction, as measured by cross-sectional area on high-frequency ultrasound images . In contrast, in patients with nutcracker esophagus, the pressure peak follows increase in cross-sectional area, suggesting that the two muscle groups are not in synchrony with exaggerated contraction, which represents a CWA.
In fact, these abnormal perception concepts are borne out on functional magnetoencephalography . Normal subjects demonstrate symmetrical activation of the sensorimotor cortex with swallowing. Patients with functional dysphagia not only have abnormal activation of these areas, but also demonstrate activation of areas depicting vigilance and self-monitoring. These in turn may interfere with downstream sensorimotor control of deglutition . Therefore, both abnormal motor function and abnormal perception or increased vigilance may participate in functional esophageal symptoms. It is possible that abnormal peristalsis, possibly in the form of contraction wave abnormalities, could be epiphenomena of the increased vigilance that is seen with these disorders. There is limited data suggesting that contraction wave abnormalities can also be seen as a consequence of distal esophageal obstruction , or from respiration-induced motion artifact in esophageal pressure phenomena . In assessing symptom burden in the context of contraction wave abnormalities, these different CWA may have similar relationships to esophageal symptom burden.
Characteristics of contraction wave abnormalities:
Contraction wave abnormalities not identified with HRM software tools include the following (Fig. 4.1):
Exaggerated contraction amplitudes: With conventional manometry, mean distal esophageal contraction amplitudes >180 mm Hg identified “nutcracker esophagus.” With Chicago Classification v 2.0, DCI > 5000 mm Hg cm s was designated “hypertensive peristalsis”  but this was eliminated from Chicago Classification v 3.0, mainly because healthy controls sometimes have contraction amplitudes within this range . Only contraction amplitudes >8000 mm Hg cm s are currently recognized as hypercontractile (jackhammer esophagus), when two or more sequences demonstrate this abnormality. However, contraction amplitudes that do not meet this threshold in the esophageal body may have clinical manifestations similar to hypercontractile disorder, and as discussed above may associate with lowered thresholds for esophageal perception [9, 18]. This may manifest on HRM as merging together of the two smooth muscle contraction segments, with obscuring of the trough between these two segments [9, 29].
Simultaneous contractions: While premature contractions are identified using DL (<4.5 s), simultaneous contractions limited to the smooth muscle esophagus without a shortened DL are not captured by Chicago Classification v 3.0. Simultaneous contractions are identified by evaluating contraction front velocity 3, 8, and 11 cm above the lower esophageal sphincter; velocity >8 cm/s is diagnostic of simultaneous contractions, and >20% simultaneous contractions are abnormal. Simultaneous contractions with normal DL can manifest esophageal motor and symptomatic features similar to DES .
Double and multiple peaked waves: On conventional manometry, these manifest as double or multiple peaks of contraction, with at least 10 mm Hg difference between the peaks. On high-resolution manometry, contraction segments are identified as overlapping, with the third segment sometimes simultaneous or even retrograde .
Prolonged wave duration: This can be associated with exaggerated contraction amplitudes and multiple peaked waves. Normal duration of the esophageal contraction wave is <5.7 s. In many instances, prolonged wave duration may be associated with DCI in the hypercontractile range.
Distal shift in contraction vigor: This is another abnormality that may not been captured using DCI, and represents a more prominent third smooth muscle contraction segment compared to the second segment . A surrogate marker for distal shift in contraction vigor consists of distal esophageal contraction amplitudes in the 150–180 mm Hg range. This finding has been associated with acid sensitivity, suggesting increased esophageal perception [20, 27].
How Are Contraction Wave Abnormalities Relevant to My Symptoms?
Existing data in the literature suggest that CWA may be clinically relevant, especially when dysphagia is a presenting symptom. In past studies evaluating patients with nonobstructive dysphagia, CWA, especially simultaneous contractions, were more evident compared to normal volunteers, both with routine conventional manometry and with provocative studies using esophageal air or fluid infusion [31, 32]. Simultaneous and retrograde contractions have been induced by balloon distension studies, both using conventional manometry where typical symptoms were reproduced with balloon distension , and more recently, using the functional luminal imaging probe and evaluating esophageal luminal diameter changes in response to balloon distension . In some symptomatic patients, limited data suggests that asynchrony between esophageal circular and longitudinal muscle contraction can potentially explain bolus transit abnormalities .
Alternatively, increased esophageal sensitivity and hypervigilance are reported in conjunction with contraction wave abnormalities, especially in the setting of perceptive symptoms like heartburn and chest pain [18, 19, 34]. Esophageal perceptive thresholds are lower in the presence of CWA [18, 22], CWA may participate in esophageal acid sensitivity , and the presence of CWA contributes to persisting esophageal symptoms following successful antireflux surgery . Further, exaggerated esophageal body contraction patterns (distal shift in contraction vigor, merged esophageal body contraction segments) represent a continuum in terms of esophageal symptoms, and only the most extreme of these patterns are identified by Chicago Classification designations . Many of the CWA have been linked to abnormal esophageal inhibitory function , with an inverse relationship between the degree of inhibition and the propagation velocity of deglutitive contraction, as well as an absence of inhibition in simultaneous contractions . Finally, functional magneto-electroencephalographic studies demonstrate activation of cortical areas depicting vigilance and self-monitoring in perceptive esophageal symptoms like dysphagia, which in turn may interfere with downstream sensorimotor control of deglutition and generation of abnormal motor patterns . These data suggest that CWA could represent a minor motor disorder which may not be pathognomonic for a defined motor diagnosis, but one which can potentially explain esophageal symptoms, particularly transit symptoms like dysphagia.
Breaks in Peristaltic Integrity
Integrity of the peristaltic wave relies on adequate formation of esophageal body contraction segments. In particular, the second segment, which is the proximal of the two smooth muscle contraction segments, can form poorly in hypomotility disorders, resulting in prominence of the trough between skeletal and smooth muscle contraction segments [35, 36]. This trough, which has been termed intersegmental trough or a transition-zone defect, has been linked to dysphagia, and indeed, bolus retention has been identified at this location using HRM with impedance [35, 37–39]. Studies using HRM with impedance suggests that breaks of >2 cm in the 20 mm Hg isobaric contour may be variably associated with impaired bolus clearance, while breaks >5 cm are uniformly associated with bolus escape [38, 40]. However, the association with dysphagia is not perfect, and the trough can be identified in healthy normal individuals, suggesting that the mere presence of a trough is not abnormal . For this reason, focus has shifted to measurement of vigor of remaining contraction segments when such troughs are present, using DCI. The Chicago Classification v 3.0 currently recognizes >5 cm breaks as abnormal, if DCI is within the “intact” range (i.e., >450 mm Hg cm s)—these sequences are termed “fragmented.”