Motor

Catalepsy

Catalepsy is the maintenance of a posture into which a limb or the body has been passively placed, for a duration usually exceeding a minute, ending with the body slowly sinking back into a resting position. In some patients it must specifically be evoked by moving the limb through a series of increasingly uncomfortable positions before it appears. A simple bedside test involves lifting the patient's arm as if to take their pulse: if the arm remains raised once released rather than naturally being lowered, catalepsy is present.

This has traditionally been noted to fluctuate considerably: it may disappear for a day and then return, and while it often occurs in the context of mute, stuperose catatonia, it is also found in milder states of akinesia, and can appear together with obstruction, in which case the patient's body is held in the mid-flight position reached when the obstructed movement stopped.

Recognition features

• A passively placed posture is maintained, typically for more than a minute, before slowly sinking back toward a resting position
• In some patients catalepsy must be specifically evoked by moving a limb through a series of progressively more uncomfortable positions
• A simple test: lifting the patient's arm as if taking their pulse, then releasing it; failure to naturally lower the arm indicates catalepsy
• The patient must be told beforehand that they are not obliged to hold whatever position their body is placed in, since otherwise they may believe this is expected of them as part of the test, which would confound the finding

Eliciting it at interview

• Explain clearly to the patient beforehand that they are free to move and are not required to hold any position, to avoid a false positive arising from the patient believing this is expected of them
• Lift the patient's arm gently, as though about to take their pulse, and observe whether it remains raised once released rather than naturally returning to rest
• If gentle passive movement does not evoke the sign, try moving the limb more firmly into a series of increasingly uncomfortable positions, since catalepsy sometimes only appears this way

Distinguishing features

• Differs from waxy flexibility in the quality of resistance felt during the passive movement itself, which has a smooth, plastic quality in waxy flexibility
• Differs from perseveration of posture, a related but distinguishable pattern in current usage reserved for cases without a felt contraction as the limb is released
• Occurs not only in catatonia but also in other conditions affecting the mid-brain, including encephalitis, vascular disorders, and neoplasms, so an organic cause should always be considered

Common misconceptions

• That catalepsy always occurs in the context of severe, mute, stuperose catatonia; it is also seen in milder states of akinesia
• That catalepsy is a stable, unchanging sign once present; it is recognised to be highly variable, sometimes disappearing for a day or more only to return again

Related phenomena

Waxy Flexibility · Perseveration of Posture · Obstruction (Blocking) · Catatonic Stupor

Diagnostically relevant to

Schizophrenia (catatonic presentations) (links open the DSM-5 Learning Lab)

Practice this

An examiner lifts a patient's arm, as if taking a pulse, and then releases it. Rather than falling back down, the arm stays exactly where it was placed for well over a minute before slowly sinking back toward a resting position. What is this? · During a catatonia examination, a patient is not warned beforehand that they need not hold any position their limb is placed in, and their arm remains raised for several minutes after being lifted. Before revealing the answer: is this finding fully reliable as catalepsy? · A patient's limb stays where it is placed during a motor examination. Before revealing the answer, decide what distinguishes catalepsy from waxy flexibility. · You want to test a patient for catalepsy during a motor examination. Before revealing the answer, decide how you would go about it. · Explain why telling the patient beforehand that they need not hold the position is essential to testing for catalepsy validly, rather than an optional courtesy.

Illustration

A clinician lifts the wrist of a mute, stuperose patient as if to check her pulse, and on letting go finds her arm remains suspended in mid-air rather than falling back to her side, staying raised for well over a minute before very slowly sinking back down on its own.

References

• Casey, P. & Kelly, B. (2019). Fish's Clinical Psychopathology, 4th ed. Ch. 8, 'Motor Disorders'.