Clinical manifestations

Presentation and course

Despite nearly two centuries of study of automatic-voluntary dissociation, little is known of its natural history, and comprehensive reviews have not been published; however, individual examples of this phenomenon abound and will be indicated here. In particular, this article will review automatic-voluntary dissociation for whether volition or automaticity is more associated with impaired action.

Automaticity better than volition. This dissociation is the more widely appreciated form because clinicians are especially impressed when a person who can do something mindlessly nonetheless cannot perform the same action when commanded. The illnesses below are grouped into three different broad sets of phenomena.

Automatic-voluntary dissociation affecting cranial nerve control. A broad array of automatic-voluntary dissociation syndromes that affect the control of the muscles supplied by the brainstem has been reported. A general term for such disorders is “pseudobulbar palsy” (73), in which supratentorial lesions inhibit brainstem outflow. Pseudobulbar palsy includes cranial muscle inactivity, impaired cognition, and disinhibited emotion (commonly termed “pseudobulbar affect”) (64; 86). In some instances, the disturbances affect just one muscle or set of actions (eg, orbicularis oris, levator palpebrae). In other instances, automatic-voluntary dissociation extends to multiple cephalic muscles in the same patient. A list of various specific pseudobulbar palsies follows.

Disturbances of eyelid control. Case reports have indicated inability to voluntarily open the eyes following right hemisphere infarction (60). One such patient was unable to keep her eyes open even after her eyelids had been passively elevated—unless she were distracted from the action by being requested to perform a visual task such as counting the examiner’s fingers (29). Afterward her eyelids would fall shut again. Similar phenomena have been observed in parkinsonian syndromes (69). The opposite disorder, of impaired voluntary eye closure despite spontaneous blinking, has been reported in amyotrophic lateral sclerosis (01).

Oculomotor disturbance. Since the early 20th century, “spasm of fixation” has been described following acquired brain illness (61). In this disorder, the patient cannot break his gaze from an object that has been presented during formal testing, but the fixation can be broken when another object is placed between the patient and the fixated object, or with blinking. A related disorder is termed “oculomotor apraxia,” part of the triad of Bálint syndrome, in which the patient cannot shift her eyes’ position to command but can reposition them spontaneously (10).

Hemifacial palsy. Since 1879 neurologic researchers noted that some patients with brain lesions who could grimace only in a lopsided manner when commanded could nonetheless fully smile immediately to a humorous stimulus (87; 126; 49).

Foix-Chavany-Marie syndrome / anterior opercular syndrome. Also termed “central facio-linguo-velo-pharyngeo-masticatory paralysis” or other unwieldy epithets, the disorder presents bilateral lower facial paresis that can change with emotional excitation. A Magnus of Germany reported a young woman who abruptly sustained persistent bilateral lower facial, lingual, and pharyngeal palsy following a miscarriage (78). Nonetheless, the woman could involuntarily laugh and swallow her saliva only after it had filled her mouth. This was the earliest published instance of automatic-voluntary dissociation. A stroke was thought to have been responsible. In one case of Foix-Chavany-Marie syndrome, following bilateral frontal opercular cortical infarctions, the automatic-dissociation of facial control also involved limb movement; the patient could not operate a remote control with his right hand, and yet spontaneously shook hands when greeting a visitor (56).

Spasmodic dysphonia. This involves involuntary hoarseness from disinhibited laryngeal muscular contractions, but with intact vocalization when singing or spontaneously crying or laughing (117; 26).

Vestibular disorder. It is possible to assess healthy volunteers’ responses to visual stimuli during the short-term zero-gravity environment of parabolic air flight. The environment, thus, “unweights” the vestibular inner ear apparatus. An experiment demonstrated that automatic visual attention to abruptly appearing lateral visual stimuli was improved, compared to participants’ being required to voluntarily orient visual attention away from such abrupt lateralized visual stimuli (102). The authors suggest that healthy vestibular function, in normal gravity settings, may be engaged for voluntary redirection of visual attention, and may be disrupted in vestibular disease.

Automatic-voluntary dissociations involving intracranial muscles.

Respiratory inspiratory apraxia. This refers to the inability to breathe deeply, but with preserved inhalation and exhalation when being distracted, such as when asked to cough or put the mouth to a woodwind musical instrument. It was first described by Jackson (58); many other instances were subsequently described (127; 41; 50; 07).

Parkinson disease. Many a neurologist learns the untested maxim that when someone shouts “Fire!” in a crowded theater, the patient with Parkinson disease is the first out of the door, despite bradykinesia or freezing of gait during formal examination in the clinic. This exemplifies the activating influence of extreme emotional arousal on automatic routines for patients who otherwise could be considerably limited in their limb actions. Souques first drew attention to a phenomenon that he termed “kinésie paradoxale,” in which patients with Parkinson disease fluctuated in their ability as well as ease for performing activities such as speaking or running (107). Souques was mystified about this phenomenon, but noted that distraction from the task could improve action. Denny-Brown cited research (16) that patients with dystonia could be induced to catch a ball when abruptly thrown to them to overcome their impaired limb movement (35). Rhythmic cueing with a metronome can entrain walking in patients with Parkinson disease who otherwise have gait difficulty (115). Persons with impaired gait from extrapyramidal movement diseases (Parkinson disease, poststroke ballism) may temporarily normalize their locomotor leg movements by adopting rhythmic repetitive movement, such as bicycling and marching (105). Persons with Parkinson disease can also be superior to healthy individuals in their reflexive (automatic) orientation of attention to environmental stimuli, as shown on a saccade task (15). High-contrast visual stimuli can induce walking in persons with Parkinson disease, such as by looking at floor tiles that periodically alternate in brightness or by using a laser cane (92).

Essential tremor. Essential tremor has been reported to preserve automatic limb movements over voluntary motion (42). In particular, patients note that they conduct fast limb movements better than when they are required to move slowly and deliberately.

Progressive supranuclear palsy (PSP) involves the reduction of spontaneous activity, limb and postural rigidity, and most characteristically the spontaneous reduction of vertical eye movements. Another characteristic of progressive supranuclear palsy is spontaneous limb elevation. In a case report of progressive supranuclear palsy, the authors observed that such bilateral slow limb rising appeared specifically when they requested the patient to close the eyes and extend the limbs, and not in other situations (37). The elevation persisted for a few minutes.

Focal dystonia. Also termed “task-specific dystonia,” focal dystonia characterizes task-specific limb movement disorder that appears in otherwise healthy professionals who rely on advanced and overpracticed specific motor skills, aggravated by attention to the particular movement. “Yips” (more often termed “the yips”) is a form of focal dystonia that can plague professional golfers. Yips involves jerks, tremors, or spasms during sport, but not other, more routine activities that less require attention (83). Focal hand dystonia can also afflict professional musicians, specific to their particular instrument (108). Writer’s cramp is another variant (104), often in individuals who extensively use penmanship. As noted by Shamim and colleagues, focal dystonia can also appear in the cranial muscles, specifically those affecting the mouth, as with professional musicians who must blow forcefully and shape their lips precisely. Rarely, focal dystonia can occur without excessive practice. One example reported was involuntary torsion at the wrist only with habitual spoon use, without extending to other implements (106). Further details may be found in the MedLink Neurology article, Limb dystonia.

Stroke. Cerebral infarction has been noted to involve automatic-voluntary dissociation of limb control. Nagaoka and colleagues observed a patient’s inability to move one leg following contralateral motor area infarction (90). In contrast, the patient demonstrated intact leg movement rhythmically when standing while assisted by a therapist. Mark and colleagues observed a patient with an acute unilateral subthalamic infarction and bilateral upper and lower limb ballism (81). The wild gyrations of the limbs became controlled with having the upper limbs conduct a rhythmic bilateral forearm rolling maneuver, and the legs became better controlled when the patient marched in a rhythmic pattern.

Ideomotor apraxia is the inability to execute skillful movements (for example, using a tool or gesturing) despite the ability to make unskilled movements (for example, reaching). Brain-lesioned adults who show ideomotor apraxia under laboratory conditions, eg, pretending to use an imaginary hammer, gesturing when commanded, or using the real object on command, can nonetheless complete such activities spontaneously and effectively under real-world circumstances when they are not commanded (30; 11; 128; 98; 121; 22). To a lesser degree, healthy individuals can also show automatic-voluntary dissociation for praxis. Thus, it has been noted that healthy subjects are unable to accurately pretend to self-tie shoelaces or a necktie without the actual object (18), and they often make the error of shaping their hand instead of simulating handling the tool (eg, scissors), which are termed either “body part as object” or “body part as tool” errors (99). Commonly, persons with ideomotor apraxia do not complain of the disorder, although exceptions occur. Further details may be found in the MedLink Neurology article, Apraxia.

Avoiding behavior involves the episodic and involuntary failure to move a limb or move it away from a stimulus (34) on command. Case reports indicate stiffening of the limb when the patient is requested or concentrates to move it, unlike during spontaneous daily living activities (91; 76). Similarly, transient immobility aggravated by attention has been observed in patients with alien hand (123) and can also affect their gait (02).

Automatic-voluntary disturbances affecting miscellaneous behaviors.

Aphasia. Aphasia entails several forms of automatic-voluntary dissociation. Limited speech output in aphasia may be overcome either by emotional upset, leading to swearing (57), reciting overlearned passages (eg, nursery rhymes), or singing familiar songs (129). On most likely the same basis, it has been noted that aphasic patients with impaired expression can become more fluent and spontaneous in their speech when they talk to dogs rather than to therapists (77). Further details can be found in the MedLink Neurology article, Perisylvian aphasias.

Wernicke aphasia (and other forms of perisylvian aphasia) entails impaired word repetition during formal testing. In a clever evaluation, the examiners had the patients repeat aloud an object’s name that was to be located in a drawing (94). This repetition was superior to formal testing. Motivation or overcoming performance anxiety may have accounted for the difference, ie, word retrieval became easier when the context was either more familiar or perhaps enjoyable.

Catatonia involves extensive suppression of spontaneous voluntary activity, most notably acquired mutism. In addition, catatonia includes limited attention by the patient to the surrounding environment. Emotional distress and the presence of the examiner can aggravate catatonia, whereas the patient not being closely observed becomes more engaged with the environment (124; 51).

Agraphia. Agraphia can appear as an automatic-voluntary dissociation when patients cannot write isolated alphabet letters from memory on command, but can nonetheless write the same letters when they are embedded in familiar words and the patients are told to write quickly (75). The etiology was attributed to parieto-occipital lesion.

Aprosodia. Aprosodia involves impaired meaningful speech intonation (for example, sounding angry or emphatic). Aprosodia is invariably assessed under laboratory or clinical conditions on command. When patients are tested to impart emotional tone to their speech, they are directed as if they are actors, ie, they are acting. However, diagnosing aprosodia in neurologic patients can be prone to error because healthy individuals may fail similarly on tests of prosodic production (05). The authors suggested that the subjects’ unfamiliarity with clinical test conditions might have caused their failures. The performance of such individuals might, therefore, represent automatic-voluntary dissociation because healthy individuals have normal speech intonation in spontaneous, familiar, real-world conditions that can arouse emotions. Further details can be found in the MedLink Neurology article, Aprosodia.

Environmental dependency syndrome. This refers to the deployment of spontaneous, naturalistic behaviors when the otherwise inactive patient is brought to a familiar setting or situation. The syndrome was first described by Lhermitte, who brought patients with brain tumors into familiar settings such as an apartment (which was designated for the patient to be a museum) and a bedroom (72). This intervention automatically instigated the patients’ activities that were congruent with the specific environments, who, in contrast, lacked initiative during standard clinical examination. In another case, a young teacher who had substantial apathy following bifrontal infarctions began lecturing when he was brought into a classroom (52). Another example can be found in patients with traumatic brain injury who do not speak spontaneously in their hospital rooms during bedside examination. They nonetheless may start conversing fluently when they are telephoned without warning, even though the calling examiner is located just outside of their rooms (17).

Functional neurologic disorder. Previously called psychogenic neurologic disorder, conversion disorder, or hysteria, this disorder entails the loss of control of a voluntary action (either movement, memory, perceiving external stimuli, or speech) in relation to attending to the process. In contrast, distraction from the problem ameliorates it. The diagnosis is supported by the absence of a brain imaging lesion that would otherwise appear to disturb the process being examined. This disorder is detailed in the MedLink Neurology article, Functional neurologic disorders and related disorders. As noted in the article, patients with functional neurologic disorder can have anomalies on experimental brain imaging that are not seen in healthy individuals. This suggests that the disorder has a neurobiological basis, although the mechanism that relates the brain imaging findings and the particular functional symptoms is not clear so far. Mark has shown that functional neurologic disorder features are widespread in common neurologic disorders, which queries whether there is the need for such a separate illness term (80).

Volition better than automaticity. The term “automatic-voluntary dissociation” is less often used for illnesses in which activities are performed better voluntarily than automatically. Furthermore, it is not surprising that the clinician may improve performance by urging the patient to perform a task, compared to spontaneous activity. Consequently, the term “automatic-voluntary dissociation” is generally not applied in these instances. Some noteworthy examples are presented here.

Automatic-voluntary dissociation affecting cranial nerve control. In some cases, hemifacial palsy can appear only in response to emotional stimuli (particularly, listening to a joke) and not when showing one’s teeth voluntarily (87; 126). A peculiar case of a boy with voluntary paresis of the right side of the face and emotional paresis of the left side of the face was documented; the etiology was undetermined but associated with epilepsy (96).

The early literature on hemifacial palsy introduced the words “mimetic” and “mimic” with regard to smiling, but confusingly. SAK Wilson referred to “mimic palsy” for the situation when hemifacial paresis appears only during emotional stimulation because the disorder mimics the hemifacial paresis that is encountered more often when smiling on command (126). In his report, Wilson later referred to “mimic movement” as mouth movement that is under emotional control. Subsequently, Feiling referred to “mimetic facial paralysis” in a child (40). Husain referred to “mimetic smiling” as that which occurs following emotional arousal, but not specifically in relation to paralysis (55). Accordingly, the word “mimetic” in current otolaryngological use refers to both the emotional control of the mouth as well as oral paralysis, specifically to emotional stimuli (44; 28; 85).

“Inverse” Foix-Chavany-Marie syndrome has been described in a case of bilateral opercular brain metastases (19). The patient had progressive difficulty with spontaneous orolingual movements, but relatively good control of these movements on command.

Automatic-voluntary dissociations involving intracranial muscles. The supplementary motor area syndrome commonly follows medial frontal brain surgery, particularly brain tumor resection or seizure surgery (66; 95). Such patients are spontaneously akinetic, primarily parts of the body that are contralateral to the surgery, and exhibit reduced speech, but with intact response to command. Depending on the extent of clinical evaluation, the supplementary area syndrome can be mistaken for consistent hemiplegia. This disorder characteristically recovers within a couple of weeks.

Unilateral spatial neglect involves the asymmetric deployment of action or attention to the space surrounding the patient, such that the patient will fail to attend or act well to one side, usually opposite the side of brain damage. The manifestations of neglect highly depend on the particular spatial tasks that are being evaluated, and, thus, do not appear consistently across all activities. Automatic-voluntary dissociation in neglect can appear on spontaneous everyday activities and can be reduced with the clinician’s directing of the patient’s attention during formal search exercises (14). Further detail can be found in the MedLink Neurology article, Neglect.

A common acute finding in neglect, particularly when it is severe, is Vulpian sign, which is spontaneous conjugate gaze deviation away from the side of neglect (47). The fixed gaze deviation can be overcome by strongly commanding the patient to look toward the neglected side, assisted by waving a visible object toward that direction.

Motor neglect is a variety of unilateral spatial neglect that involves the reduced spontaneous use of the limbs to one side on routine activities without attending to the limbs, but that can be overcome by the direct command to move the limbs (84; 27; 23; 103).

Limb nonuse resembles motor neglect. Both disorders involve the reduced spontaneous use of a limb on one side, with improvement to command, but their etiologies are hypothesized to differ. Motor neglect is considered to be an attentional disorder, whereas limb nonuse is believed to result from the behaviorally conditioned inhibition of using a neurologically impaired limb following ineffectual movement attempts, with simultaneous adequate compensation by either another part of the body or another individual (114). Andrews and Stewart first observed that patients with hemiparesis could be disinclined to use their paretic limbs at home—where one would normally use the limbs spontaneously—and yet could move them adequately for everyday activities in the clinic on command (06). The investigators suggested that this discrepancy may have arisen from the differences in expectations between the caregivers and the therapists: family caregivers either expected less self-efficacy of the patients or were overprotective. The behavioral disorder of limb nonuse was elsewhere supported by experimental observation (109). Hemiparetic individuals would not use the paretic limb when they were asked to perform a series of functional movements (eg, touch one’s nose and then open a window) without specification that the patients use the paretic arm. Instead, the patients used the other limb. In contrast, when the patients were asked to specifically use the paretic limb to perform the same activities, the paretic arm was effective.

Idiopathic toe walking is an involuntary, uncommon behavior among children, otherwise healthy, who tiptoe habitually. Such behavior is noted to reduce when the child is directly examined (116).

Automatic-voluntary disturbances affecting miscellaneous behaviors. Impaired action initiation is not uncommon when brain illness involves the frontal lobes (46). This can be overcome by external stimulation, such as a nonemotional command. This dissociation is characteristic of apathy (89). In language, this dissociation can be manifest as transcortical motor aphasia (a form of extrasylvian aphasia, also termed “dynamic aphasia”), in which patients are commonly mute but can immediately repeat sentences very well when requested (04).

Combined automatic and voluntary deficit in neurologic disease. In a few disorders, changes in action can follow from both emotional excitation and increased attention by either an order from another person or self-generated concentration, in contrast to the condition without either of these forms of stimulation.

Callosal alien hand involves the apparently involuntary execution of skillful activities by one hand (eg, unbuttoning a shirt), despite the individual not wanting to do them, following injury either in or along the corpus callosum. This damage substantially disrupts the neural communication between the cerebral hemispheres. Several investigators have observed that such patients can complete ordinary daily living activities without much attention, whereas other activities that require increased attention can aggravate the alien hand syndrome (02; 12). Such patients found they could control alien hand by detaching their attention from the task. In other reports, however, the involuntary hand movement was aggravated by emotional stress (33; 21). The relationship between attention and emotional distress is unclear in this disorder. It is possible that aggravation of the alien hand following emotional distress may be a byproduct of being upset at the lack of manual control, and, thus, involves enhanced attention to the disorder. The automatic-voluntary dissociation for alien hand, therefore, may not be as complex as it may at first seem. Further observations of alien hand are needed to understand whether emotional excitation not associated with frustration can affect the disorder. The MedLink Neurology article, Alien hand syndrome, provides further details.

Automatic-voluntary dissociation in alien hand may also have a complex appearance that is not associated with emotional arousal. Thus, in at least one case, alien hand had “inverse automatic-voluntary dissociation” when the behavior appeared spontaneously everyday, but became controlled with deliberate attention to the disorder (74).

Tics are disruptive, involving abrupt unwanted movements, which come in broad varieties. Tics can be suppressed by attending to them and resume with distraction (24). However, paradoxically, tics can also be aggravated by emotional excitation.

Autoactivation deficit, formerly termed “psychic akinesia,” involves substantial inertia, but with release of fairly normal behavior in response to confronting an emotionally engaging situation with other individuals or being ordered to a task by another individual (65). Thus, in this condition both automatic activation (in response to sharing joyful moments with the family) and voluntary activation that raises the patient’s attention can occur when obeying a command. Some patients with autoactivation deficit can report that they are dreaming when they are abruptly awoken, despite reporting that they have vacant mental content when they are ordinarily awake (71). Individuals with autoactivation deficit believe they are in control of their actions, yet they are puzzled by their lack of initiative. The disorder overlaps the immobility of Parkinson disease and, in particular, kinésie paradoxale to emotional stimuli, but without freezing of movement.

Prognosis and complications

The natural history of automatic-voluntary dissociation is seldom described, in contrast to the course of the underlying disease. One exception is a report of a young man who sustained bifrontal infarctions and consequent environmental dependency syndrome (52). The syndrome remitted over the following year. The supplementary motor area syndrome referred to typically spontaneously resolves in a few weeks (66; 95).

Complications are not specifically referred to as automatic-voluntary dissociation, but rather the underlying diseases that are covered elsewhere in MedLink Neurology.

Clinical vignette

A 22-year-old man with a history of metastatic testicular cancer metastases to his brain presented to the emergency department with acute impaired speech production without loss of comprehension, along with right hemiparesis. He was found to have an acute left frontal lobe hemorrhage, which prompted surgical excision from the associated tumor.

During postoperative examination, the patient was noted to have the inability to protrude the tongue on request, but nonetheless, he automatically protruded his tongue without request when he was presented an ice cream cone to eat. This clinical presentation represents Foix-Chavany-Marie syndrome, as described under Clinical manifestations: Automaticity better than volition.

Biological basis

Anatomic localization

The occurrence of automatic-voluntary dissociation following differently located brain lesions suggests that specific actions may rely on more than one brain area or network. However, reported instances of automatic-voluntary dissociation have not been shown to be consistently related to brain imaging findings.

For example, although Foix-Chavany-Marie syndrome has also been termed “anterior opercular syndrome,” the occurrence of other lesion sites argues against this anatomically specific term. Thus, some case reports have observed that the disorder acutely follows unilateral rather than bifrontal opercular lesion, either combined with preexisting brainstem lesion (93) or without the ability to demonstrate any other lesions either on MRI or functional imaging (45; 130). The latter authors speculated that such presentations of bilateral motor deficits following solitary lesions could either reflect anomalous neural pathways or that bilateral lesions could still be present but would require much more refined imaging technology to be demonstrated.

Facial paresis at rest that can be overcome by emotional stimuli typically follows lesions in or close to the corticospinal tract. In contrast, facial paresis from emotional arousal but intact control in other situations can follow lesions in or near the cerebellum (40; 53), as well as other cerebral locations (54; 118). There may be an anatomical basis for selective automatic versus voluntary facial dyscontrol. Pyramidal motor fibers, when lesioned, may result in impaired voluntary facial movement, whereas lesion of the midcingulate cortex may selectively impair automatic, emotional facial movement (85).

These findings, all together, suggest that there is not a straightforward relationship between lesion location and paresis that differentially affects voluntary versus automatic movement.

Pathophysiology

In the same way that consistent lesion localization does not occur in forms of automatic-voluntary dissociation, a unifying physiological explanation governing this dissociation has not been identified. Because many instances of opposing forms of automatic-voluntary dissociation have been described following localized brain lesions (ie, deficits more affected by automatic processes compared to voluntary processes), this has prompted consideration that anatomically discrete pathways are specialized in either automatic or voluntary actions. But, thus far, the literature has not distilled an anatomical explanation for the physiology.

The physiology involved with ordinary habit acquisition during normal maturation—essential to most automatic behavior—is also, thus far, not clear. However, it has been shown that healthy individuals who practice automatic speech such as counting can involve greater right than left hemispheric blood flow (67). According to a model, the right hemisphere mode of acting is to act in the most rapid, straightforward manner, whereas left hemisphere processing involves deliberation, evaluating various alternative solutions before proceeding with action, even when this mode can be detrimental (101). Practicing a new verbal task (generating a verb when shown an object) converts from one particular blood flow pattern (increased in left frontal and temporal cortex, right cerebellum, and anterior cingulate; reduced in bilateral insular cortex and left medial extrastriate cortex) to the opposite pattern after 15 minutes (97). It is not yet possible to indicate whether such practice-induced regional cerebral blood flow changes occur generally or only for this task. However, these findings support the concept that automatic activities engage different brain areas than voluntary activities. These changes may pertain to the general process of practice-induced habit or skill acquisition, which is also called procedural learning. Such habit acquisition, in turn, may permit producing certain behaviors under automatic conditions when they cannot be produced very well voluntarily, such as during disease or the neurologic effects of aging.

When testing purportedly “voluntary” actions, one should consider the possibility that performance deficits in brain-lesioned subjects may result simply from unfamiliarity with the process of formal examination or the test environment, such as the laboratory. After all, subjects are expected to “perform” in a manner and situation that may be both unfamiliar as well as intimidating, which may change the behavior from its spontaneous character in the community. Alvarez and colleagues noted that their healthy control subjects were only minimally different from brain-lesioned subjects during formal tests of linguistic prosody (ie, vocal intonation to alter the intended message) (05). The investigators, who were Chilean, were surprised because they failed to replicate the finding of much more considerable differences between patients with brain lesions and control subjects demonstrated in an American study. They conjectured that their subjects came from much more impoverished backgrounds, and, thus, that the novelty of formal scientific examination may have suppressed the elicitation of ordinary speech intonation during performance to command. They could not, however, exclude the possibility that socioeconomic status may have had a direct neurobiological effect, as opposed to unfamiliarity with the tasks. However, the findings remind us that one must always be cautious about presuming that formal test to command under unfamiliar and artificial conditions reflect everyday behavior.

Automatic-voluntary dissociation during unilateral spatial neglect may represent either (1) task-specific neglect, which is well-known to occur even on standard neuropsychological tests, or (2) the differential engagement of spatial attention during commanded versus routine activities. The former is suggested by the uncommon double dissociation in neglect between standard, abstract tests of spatial attention versus observations on daily living activities (08). A determining factor for the latter may be the ease of performance. Thus, for example, if standard neuropsychological tests are too easy, they may fail to elicit neglect that would otherwise appear during more difficult activities. Neglect that appears during daily living activities, and not during standard neuropsychological tests, may represent the increased attentional challenge that can come with the former, for example, by having to attend to multiple concurrent activities (112). Support for the ease of task performance hypothesis also appears when stroke patients who appear to have long ago recovered from unilateral neglect may nonetheless show neglect again when they are given a mild sedative, which may require additional attentional resources for task completion compared to the unmedicated condition (68).

Many behaviors described here resemble functional neurologic disorder, except that the latter typically (and, for many, by definition) lack a lesion that would be expected to produce the deficit when patients would be impaired when distracted from the task. Functional neurologic disorder shares with other disorders described here the feature that the deficit is apparent specifically during attention to the deficit and improves with distraction and, thus, automatic responses. Consequently, functional neurologic disorder may not be a considerably different disorder. Moreover, although conventional brain imaging fails to identify a lesion that would ordinarily produce the deficit during inattention to the task (eg, hemiparesis apparent when distracted from the deficit, in the case of a brain infarction), experimental imaging techniques such as functional MRI, PET scanning, and voxel-based morphometry find focal abnormal physiology or structure when compared to healthy individuals (100).

Thus, the definition of functional neurologic disorder may require revision because focal brain imaging deficits are commonly found when using experimental, but no less valid, brain imaging techniques. Consequently, this raises the possibility that all disorders in which actions are improved during distraction or emotional upset and are worse during attention may be “functional.” If so, then it would be important to consider physiological hypotheses for functional neurologic disorder to explain other kinds of automatic-voluntary dissociation.

A physiological mechanism has been hypothesized for functional neurologic disorder in which patients following a marked physiological or psychological injury may have impaired intrinsic feedback when preparing actions when they are paying attention to them, resulting in impaired ability to predict the consequences of planned actions and, as a result, deficient action (38). This mechanism is hypothesized not to occur (or occur less) during inattentive activities.

During automatic-voluntary dissociation, when automatic activities are performed better, Cathala and Metellus argue that this is an illusion (25). For aphasia, although patients can speak automatically to some extent, it is nonetheless corrupted. In contrast, the voluntary intent to speak remains. However, because voluntary speech depends on intact automaticity, then corrupted automaticity undermines voluntary speech as well. It remains to be seen whether this criticism can apply to other forms of automatic-voluntary dissociation, such as comparatively simple actions like mouth opening.

Differential diagnosis

Confusing conditions

The confusion involved with automatic-voluntary dissociation most likely may lead clinicians to incorrectly infer that intact (or improved) automatic performance assures the absence of neurologic disease, rather than misattribute automatic-voluntary dissociation, when recognized, to a different condition.

Some disorders can involve improved neurologic control or activity in relation to attention, but they do not justify diagnosing automatic-voluntary dissociation because they (1) occur at times during impaired consciousness, (2) involve simple reflexes, or (3) can involve delayed rather than completely lost voluntary activity despite intact automatic activity.

The congenital central hypoventilation syndrome, informally termed “Ondine curse,” refers to the pediatric disorder of insensitivity to blood carbon dioxide levels, causing reduced automatic breathing while asleep in children (131). Although superficially this appears to be the inverse of respiratory inhibitory apraxia, the suppression of breathing characteristically occurs during sleep. It is best to consider automatic voluntary dissociation as pertaining to individuals only when they are awake.

Deep tendon (myotatic) reflexes would obviously not qualify as automatic-voluntary dissociation, even though a tap to a tendon can immediately cause a jerk in an otherwise immobile limb, because attention (or its lack) is not involved. More intriguing are associated movements in which a paretic limb can stereotypically flex for a few seconds after the patient either yawns or sneezes (122). As with deep tendon reflexes, associated movements imply intact neural supply to the affected muscles. As before, these phenomena do not reflect an effect of attention to the actions.

Similarly, one should exclude reflexive blink to visual threat in persons with impaired ability to close the eyes voluntarily (70; 79). Although the patient is “threatened” and, thus, at the point of perceiving harm, the patient invariably has insufficient time to contemplate the threat; the nervous system automatically and rapidly reacts by causing blinking when an object’s extent in the visual field suddenly expands, as if it were rapidly approaching.

The unconscious thought effect occurs in healthy individuals, whereby complex decision making or creative problem solving often occurs more effectively when an individual defines the problem, distracts himself from thinking about it, and then arrives at a more satisfactory result than if he were instead to conscientiously attempt a solution (36; 111). Empirical research has shown that clinical psychology students more successfully provided differential diagnoses for psychiatric disorders from case presentations that they had read when they first played word puzzles before answering questions about the cases, compared to students who were required to think directly about the cases before answering questions, over the same time interval (31). These processes are encapsulated and further demonstrated in the popular book Thinking, Fast and Slow (62), which discusses parallel mechanisms of decision-making for the same problem. The slow mechanism entails conscious, attentive thinking, which often loses the race with concurrent subconscious deliberation. Although the latter process is subconscious and not readily inspected by the person, it would not be considered to be automatic because the process nonetheless enlists logical analyses that happen to be “offline.”

Diagnostic workup

Workup is not specifically required to diagnose automatic-voluntary dissociation because the diagnosis is usually evident from clinical examination alone. Instead, workup should be directed at the suspected underlying contributing pathology.

Management

Automatic-voluntary dissociation is not a disorder per se, but rather a characteristic of diverse neurologic disorders. The observation that patients can perform activities under some behavioral conditions but not others suggests that this property could be harnessed to improve functional status, social engagement, or quality of life for the individual patient. Some treatments are reviewed in this article in notable presentations of automatic-voluntary dissociation.

The effect of visual attention to high-contrast environmental stimuli to overcome the spontaneous and involuntary freezing of gait in Parkinson disease has been utilized by equipping patients with “laser shoes”—shoes that shine a laser spotlight onto the floor in front of the patient to induce the patient to step toward the spotlight (09). Field testing of the devices in the home is awaited.

The occasional retention of singing among patients with Broca aphasia has inspired a form of treatment termed “Melodic Intonation Therapy (MIT)” (129). In this treatment, patients who can sing are trained to progressively reduce the melodic component of their statements over several weeks. At present, the success of MIT for aphasia is mixed (120; 48). Consequently, larger trials are needed.

Learned nonuse of the paretic limb following stroke or other disabling brain disorders (traumatic brain injury, multiple sclerosis, cerebral palsy) responds well to constraint-induced movement therapy (CI therapy) (113). In learned nonuse, the patient has sufficient muscle power in the paretic limb to complete routine everyday activities, yet the patient seldom uses the limb. This condition is hypothesized to occur from conditioning following inadequate movement attempts for self-care and compensating with either the less-affected upper limb or other individuals. The typical training course involves a couple of consecutive weeks of massed practice with the paretic limb on functionally relevant tasks, encouraging feedback with every training trial from the therapist, inhibiting use by the nonparetic limb during training and after-hours activities, and completing assigned activities outside of the clinic and a home diary of activities (88). The transfer of training benefits from the clinic to the community is supported by daily problem-solving discussions with the therapist. Numerous international clinical trials have identified large effect sizes of the posttreatment benefits (63). Benefits for spontaneously performed real-world self-care activities can be retained years after the short treatment course for diverse neurologic disorders (82).

Certain illnesses that are typified by automatic-voluntary dissociation (focal dystonia, functional neurologic disorder) may respond well to psychologically based physical rehabilitation. A common feature is identifying and avoiding conditions that elicit the voluntary movement impairment, minimizing attention or hyperattention to the deficit, and incorporating alternate but intact movements that are less often utilized by the patient (20; 39; 59; Sadnicka and Roset-Llobet 2019; 119). Specific forms of the general approach include sensory motor retuning for performance-related musical focal dystonia and cognitive behavioral therapy for functional neurologic disorder.

Limited evidence suggests that impaired voluntary eyelid opening and spasmodic dysphonia may improve with botulinum toxin injection to the involved muscles (32; 125).

The general topic of automatic-voluntary dissociation, despite its long history, is short with respect to unifying concepts and particularly to strategies of management. It can be expected that considerable investigation will be needed to further the care of patients whose disorders are typified by these forms of dissociations.

Outcomes

Automatic-voluntary dissociation is itself not treated. The finding of such dissociation can be used to improve the underlying disorder by bringing to the patient’s attention the dissociation. For example, the improvement of performance automatically, during intentional distraction during examination, can be used to treat functional neurologic disorder (110).