Functional Motor Disorders Mimicking Symptoms Upon Resolution of Cerebrovascular Disease

ABSTRACT

Background

Functional motor disorders encompass a variety of manifestations characterized by abnormal movements that are clinically incongruent with those known to be caused by neurological diseases.

Cases

We report 2 cases in which functional motor disorders developed after complete recovery of motor symptoms originating from underlying vascular brain lesions. The first case describes a young woman who developed a motor and sensory hemisyndrome after surgical removal of a postrolandic cavernoma. The second describes a 16‐year‐old girl who presented with a mixed component tremor after ventricular derivation and endovascular embolization for rupture of a brainstem arteriovenous malformation.

Conclusion

Motor symptoms and signs attributed to an underlying lesion may trigger “pure” functional motor disorders. In such cases, the differential diagnosis may be even more challenging. However, diagnosis of a functional rather than a defined structural disorder can be achieved by a “positive diagnostic process,” considering the findings of internal inconsistency and incongruity.

Short abstract

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Video S2

Functional motor disorders (FMDs) include a variety of manifestations (functional weakness, tremor, and others) clinically defined by abnormal movements that (1) are incongruent with their counterparts in neurological disease and (2) are significantly altered by distractive maneuvers. ¹ They are commonly encountered in clinical practice; for the patients affected by FMDs, they are highly disabling and have a negative impact on quality of life similar to that experienced by patients with neurodegenerative disease, such as Parkinson's disease. ¹

The etiopathogenetic mechanisms remain controversial. Possible risk factors include medical and surgical comorbidity, adverse childhood experience, and physical injuries. ² Because FMDs may also be familial, a positive family history for FMDs per se may act as a “model” of disease and be a risk factor for the development of these disorders. ³ Furthermore, functional neurological symptoms may coexist in patients diagnosed with other neurological disorders, such as epilepsy, Parkinson's disease, multiple sclerosis, and stroke.4, 5, 6

We report 2 unusual cases in which the patients developed “pure” functional motor symptoms following complete recovery from symptomatic motor symptoms originating from vascular brain lesions.

Case 1

In May 2014, a 24‐year‐old right‐handed woman underwent brain neuroimaging because of sporadic headaches; the imaging study disclosed a right‐sided postrolandic cavernous malformation. In September 2018, a left‐sided motor and sensory hemisyndrome developed, from which she fully recovered about 1 month after stereotactic radiosurgery. In June 2019, radical excision of the malformation was performed because of renewed bleeding and a recurrence of headache symptoms, after which she progressively and completely recovered. In early October 2019, she came to our observation because of an insidious onset of gait unsteadiness and left‐sided weakness. She also complained of left lower limb paresthesia and recurrent absence‐like seizures.

Neurological examination disclosed wide‐based gait requiring bilateral support that improved when lateral or backward (Video S1, segment 1.1). Romberg's sign was positive with multidirectional sways; it was reduced by distraction maneuvers, as was the tremor, which was both postural (upper and lower extremities) and intentional (upper extremities). Also, there was global muscle weakness (Medical Research Council scale score 4/5) of the left side (lower > upper arms) with positive Hoover's sign. Sensory modality, reflexes, and cranial nerves were intact. Brain magnetic resonance imaging was negative for recurrence or edema and 70‐hour video electroencephalogram recording revealed no electric anomaly.

A diagnosis of clinically definite FMD diagnosis was made based on the Gupta and Lang ⁷ criteria. The patient was fully informed about the diagnosis and reassured about the potential reversibility of the condition. Intensive rehabilitation was initiated and resulted in significant improvement within 4 days of treatment (Video S1, segment 1.2). At the 2‐month follow‐up examination, she was able to walk unassisted (Video S1, segment 1.3).

Case 2

On May 1, 2019, a right‐handed 16‐year‐old girl suffered an acute loss of consciousness attributed to the rupture into the ventricles of a left‐sided thalamomesencephalic arteriovenous malformation. Ventricular derivation and endovascular embolization were performed with complete obliteration of the malformation as documented by control brain computed tomography scans. A 3‐month neurorehabilitation program for the residual right‐sided facio‐brachio‐crural hemisyndrome led to the full recovery of upper and lower limb paresis. About 1 month later, she noted right arm tremor that interfered with daily life activities. The tremor consisted of 3 components (postural > action > resting). A diagnosis of Holmes' tremor was made at another hospital. Levodopa therapy was initiated (up to 600 mg per day), but brought no benefit and caused excessive daytime sleepiness (Epworth Sleepiness Scale score 13). In December 2019, she came to our attention.

Neurological examination disclosed a low‐frequency, high‐amplitude, and irregular tremor affecting the right arm: more proximal than distal, prominent during posture, and only mild during action (Video S2, segment 2.1). The tremor was fluctuating and distractible and stopped completely when she was engaged in talking or other activities (Video S2, segment 2.2). The mother and the patient were adequately informed about the functional nature of the disorder. Rehabilitation with sensory‐grounding cognitive‐behavioral impression techniques resulted in the improvement of the tremor and the patient's quality of life.

Discussion

These cases are unusual because the symptoms were initially erroneously attributed to the vascular lesions of the central nervous system given the congruity in the pattern of presentation and the anatomical correspondence. In case 1, the motor and sensory hemisyndrome could have been the clinical manifestation of a de novo cavernoma formation; similar cases have been reported in a small percentage of patients who had undergone radiosurgical treatment. ⁸ In case 2, the tremor was mistaken for a variant of Holmes' tremor because of its features: the irregular low‐frequency pattern (presence at rest and prominence during posture and action) and the timing of onset after a central nervous system insult in the thalamo‐pontine‐midbrain region, which usually occurs between 1 and 24 months, as a consequence of a vascular lesion in 48.3% of cases. ⁹

In both cases, neurological examination revealed “red flags” of internal inconsistency, such as susceptibility to distractive maneuvers and a positive Hoover's sign in case 1, and incongruity, as demonstrated by the gradient of tremor severity in case 2. Tremor was observed mainly during posture and was minimal at rest and during action, in contrast to Holmes' tremor, in which the typical gradient is action > postural > resting. Based on the positive findings of physical examination, the unremarkable investigations, and the good clinical outcomes after a personalized 4‐day rehabilitation program, a diagnosis of clinically defined FMD was made. ⁷

The 2 cases are emblematic also because the motor symptoms were “purely” functional and developed upon resolution of the symptoms arising from the cerebrovascular disease. The coexistence of symptomatic and functional symptoms is established, such as functional limb weakness in multiple sclerosis ⁵ and stroke ⁶ and the variety of functional motor symptoms (ie, paresis with Hoover's sign, stiff leg hemiparetic gait, functional bradykinesia, bent knee) in Parkinson's disease and atypical parkinsonism. ⁴ To the best of our knowledge, however, there are no cases in which a previous symptomatic motor condition subsequently “triggered” a pure FMD in the same patient. A possible explanation is the “disease modeling” hypothesis for an association between exposure to movement disorder models (from family and friends) and the development of FMDs. ³ According to this hypothesis, the experience of a movement disorder, even in the same patient, may provide a model for the development of the functional disorder. This interpretation is plausible and consistent with the concept that explains the occurrence of dissociative (nonepileptic) attacks in epilepsy. ¹⁰ In addition, abnormal expectations related to a strong illness belief, given the troublesome past medical history of these 2 patients, may have played a pivotal role in the development of the FMDs. This speculative mechanism fits somehow with the neurobiological explanation based on an abnormal overweighting of prior expectancies regarding symptoms, which might distort perception. ¹¹

Conclusions

Functional neurological disorders are commonly encountered in clinical practice and should always be suspected when elements of inconsistency or incongruity are detected on clinical assessment, also in the presence of defined structural conditions that could explain the neurological manifestation.

Author Roles

(1) Research Project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript Preparation: A. Writing of the First Draft, B. Review and Critique.

F.P.: 1B, 1C, 3A

E.A.: 1A, 1B, 3A, 3B

E.C.: 1C, 3A

I.D.V.: 3B

M.T.: 1A, 1B, 1C, 3B

Disclosures

Ethical Compliance Statement: Patients were informed and written, signed consent was obtained. The authors confirm that the approval of an institutional review board was not required for this work. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines.

Funding Sources and Conflict of Interest: No specific funding was received for this work. The authors declare that there are no conflicts of interest relevant to this work.

Financial Disclosures for the previous 12 months: The authors declare that there are no additional disclosures to report.

Supporting information

Video S1. Case 1. Segment 1.1: Gait examination before rehabilitation. Gait impairment is evident. Segment 1.2: Examination after 4 days of intensive rehabilitation and sensory‐grounding cognitive‐behavioral impression techniques. Segment 1.3: Examination 2 months after hospital discharge and at the beginning of rehabilitation. During this period the patient continued to adopt and improve the distractive tasks she learned.

Video S2. Case 2. Segment 2.1: Examination for tremor without distractive maneuvers. Note the characteristics of tremor (unfortunately, the patient rested her wrist on her leg, slightly supporting the fifth finger) that reemerge during posture but is less evident and ample on finger tapping. Segment 2.2: Examination for tremor with distractive maneuvers (sensorial and motor task). Note the tremor improvement with contralateral distractive motor tasks.