Depersonalization, the sense of being detached from or observing oneself, and derealization, the sense that the surroundings are unreal or dreamlike, are dissociative phenomena that are commonly described immediately before functional motor symptoms and dissociative attacks. Patients rarely volunteer them and often welcome the recognition that these experiences are known and named. Asking about them specifically, and normalizing them, is a practical way to build the therapeutic alliance and to explain the symptom mechanism.
The vignette also illustrates the history-taking pitfalls emphasized in this chapter. Blunt questioning about depression early in the consultation is counterproductive: patients often interpret it as an accusation that the symptoms are imagined, and around a third of patients with functional disorders have no psychiatric comorbidity at all. Enquiry about mood, anxiety, panic and dissociation is better placed after the neurological history and after the patient feels believed. Absence of a stressor or of a psychiatric diagnosis does not weaken the diagnosis, which rests on positive neurological findings.
On the ABPN blueprint this item maps to the Clinical aspects of neurologic disease axis, because the competency is recognizing and eliciting the characteristic clinical phenomenology of a functional disorder. Documenting dissociative symptoms also helps distinguish these episodes from epileptic auras when both are being considered.
Incorrect Answers
- A. Mesial temporal experiential auras are brief, highly stereotyped, often include déjà vu or rising epigastric sensation, and would be expected to show interictal or ictal electroencephalographic change.
- C. Hypnagogic hallucinations occur at the transition into sleep and are accompanied by excessive daytime sleepiness, cataplexy or sleep paralysis.
- D. Migraine aura evolves over minutes with positive then negative visual or sensory phenomena that march across a modality, not with detachment from the self.
- E. Delusional misidentification involves a fixed false belief about the identity of people or places; this patient retains full insight that the experience is not real.
Testing Pearls
- Depersonalization and derealization commonly precede functional attacks and functional motor symptoms.
- Patients seldom volunteer dissociative experiences; ask about them explicitly.
- About one third of patients with functional disorders have no psychiatric comorbidity.
- Blunt early questioning about depression is often heard as an accusation of imagining symptoms.
- Leave mood, anxiety and dissociation enquiry until after the neurological history.
References
- Jankovic J, Mazziotta JC, Newman NJ, Pomeroy SL, editors. Bradley and Daroff's Neurology in Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2022. p. 2077-2078.
- Stone J, Warlow C, Sharpe M. The symptom of functional weakness: a controlled study of 107 patients. Brain. 2010;133(Pt 5):1537-1551.
- Espay AJ, Aybek S, Carson A, Edwards MJ, Goldstein LH, Hallett M, et al. Current concepts in diagnosis and treatment of functional neurological disorders. JAMA Neurol. 2018;75(9):1132-1141.
