Functional Neurologic Symptom Disorder Resolving After Endoscopic Encephalocele Repair

Case Presentation

WX, age early 30 years, presented to the outpatient general neurology clinic for evaluation of episodes of altered awareness. WX reported normal health until 3 months previously, when the first event occurred. Since that time, 7 events with similar semiology had taken place. According to WX’s description, the events were preceded by a prodromal presyncope and a “burning smell” before onset of motor involvement consisting of right upper extremity shaking, bilateral upper extremity shaking, and jaw clenching. WX’s smartwatch recorded desaturations to 80% SpO₂ during these events. Awareness was maintained but confusion occurred during the episodes. The events, which lasted for 30 to 40 minutes, were followed by headaches of moderate intensity with migrainous features. Headaches were exclusively experienced immediately after events, with no headaches occurring at other times. WX reported a history of migraine in early- to mid-adolescence, with headaches similar in quality to those described after the events. Fatigue and “mental slowness” also occurred after the episodes, lasting 24 to 48 hours afterward. After resolution of the episodes, WX returned to baseline.

Event triggers included onset of WX’s menstrual period, stress, or poor sleep. WX had been born prematurely and experienced hypoxia at birth, although it is unclear whether related complications occurred. During childhood, WX reportedly had several nonfebrile seizures which a family member described as semiologically similar to the current episodes of altered awarness, but WX did not recall these events. There was no history of developmental delay, febrile seizures, intracranial infection, head trauma, stroke, neoplasm, vascular malformation, or drug or alcohol use. One cousin had a history of febrile seizures and another cousin had a history of narcolepsy; otherwise, no family members had paroxysmal disorders.

WX described several associated symptoms that had developed concurrently with the episodes of altered awareness including forgetfulness (eg, forgetting important birthdays), word-finding difficulties, paraphasic errors, and worsened dexterity with both hands (ie, difficulty putting on a necklace or buttoning a button). WX also described unsteadiness without falls; this was notable because WX had previously been a yoga instructor. On 2 occasions, WX had gone to bed and had awakened on the floor without recalling how they got there.

WX had several recent stressors preceding the development of the clinical events. WX had recently resigned from work. WX had been pregnant but experienced a miscarriage several months previously, requiring dilation and curettage. WX’s previously high-functioning father had recently been diagnosed with dementia with Lewy bodies; at one point, the father became agitated and attempted to strangle WX, prompting his admission to an acute psychiatric facility. WX’s mother had died of amyotrophic lateral sclerosis while WX was her primary caregiver.

WX had a history of depression, anxiety, and attention-deficit/hyperactivity disorder (ADHD), treated with therapy and a selective serotonin reuptake inhibitor. WX had been taking 100 mg lamotrigine daily for several years for treatment of mood symptoms and had been prescribed 5 mg diazepam to take during the episodes of altered awareness, which had been effective.

Diagnostic Process

Neurologic examination results were normal with no objective evidence of memory impairment, cranial nerve deficits, weakness, hyperreflexia, or sensory or cerebellar abnormalities.

A 3T epilepsy-protocol MRI, including thin-slice T1-weighted, T2-weighted, fluid-attenuated inversion recovery, diffusion-weighted, and susceptibility-weighted imaging, showed a dysplastic anterior temporal pole vs cystic encephalomalacia extending into a sphenoid bone defect along the left cranial fossa, consistent with an encephalocele (Figure). WX was scheduled for epilepsy monitoring unit admission. However, the day before the scheduled admission, WX developed bilateral peripheral vision loss and new bitemporal headaches with associated tinnitus and a positional component as well as clear rhinorrhea. WX was admitted to the general neurology service.

Figure. Left anterior temporal encephalocele: axial (A) and coronal (B) views.

During the admission, ophthalmologic examination did not show peripheral visual field deficits. Lumbar puncture showed a low pressure of 2 cm H₂O, but given technical challenges, there was suspicion that the measurement was erroneous. On repeat lumbar puncture testing, the measured pressure was 17 cm H₂O. Cerebrospinal fluid (CSF) evaluation showed normal protein, glucose, cell counts, and infectious studies. Systemic infectious, metabolic, and endocrine workups were unremarkable.

Continuous EEG monitoring had been initiated on admission, and since that time, one of the episodes of altered awareness had been captured without an electrographic correlate. There were no interictal discharges or slowing throughout the course of monitoring.

Otolaryngology was consulted for assistance with a cisternogram given the low CSF pressure result and a new positional component associated with the headaches. Otolaryngology recommended CT imaging of the sinuses, which showed left pterygoid plate defect but without clear communication with the paranasal sinuses. Based on the CT results and clinical history, there was enough clinical concern for a CSF leak to recommend surgery to correct the sphenoid defect, and a cisternogram was deemed unnecessary. WX was discharged with symptomatic treatment and scheduled for outpatient sinus surgery.

Case Resolution

WX underwent endoscopic evaluation of the skull base, during which a leaking meningocele with CSF exiting the foramen rotundum was noted. The leaking meningocele was resected, and the skull base was reconstructed. WX experienced transient postoperative numbness in the left V2 distribution but was asymptomatic 1 month later. WX has remained asymptomatic for >1 year postoperatively, with no recurrence of events.

Discussion

Functional neurologic symptom disorder with attacks/seizures (FNSD A/S) is a common finding in the workup of epilepsy, accounting for ~25% of admissions to epilepsy monitoring units.¹ A number of characteristics can help differentiate functional from epileptic events² including features in the presented case that increase diagnostic suspicion for functional events. These include bilateral motor involvement with retained awareness (although this uncommonly can be seen in frontal lobe seizures), nonrhythmic and discontinuous movements of all 4 limbs, side-to-side head movements, prolonged event duration (up to 40 minutes), association with symptoms not typically associated with epilepsy (ie, pain), and moaning.

FNSD A/S is often associated with other psychiatric comorbidities.¹ WX had a history of depression, anxiety, and ADHD; was receiving weekly therapy; and had been prescribed lamotrigine for mood symptoms. FNSD A/S also has an association with stressful events or traumas as triggers.¹ WX had several recent major stressors, including a miscarriage, declining health and cognition of her father, and the death of her mother. FNSD A/S can be successfully predicted with video assessment,³ and although a provided video was highly consistent with FNSD A/S, the gold standard for diagnosis remains continuous EEG with video capturing the typical event, which was obtained in this case.

There is frequent co-occurrence of FNSD A/S and epileptic events,⁴ and there was concern that WX may have had both. WX described a stereotyped smell of “burning” before the onset of motor symptoms, and events overall were stereotyped. WX had been born prematurely and was hypoxic at birth. Although somewhat poorly defined, WX had a childhood history of nonfebrile seizures. In addition, WX had awoken on the floor twice, potentially suggesting events occurring during sleep.

3T MRI showed an encephalocele at the left anteromedial temporal pole. Temporal encephaloceles are a relatively common incidental finding in the workup of epilepsy.⁵ There is debate in the literature regarding their role in temporal lobe epilepsy, but they are frequently asymptomatic from a seizure perspective. Temporal encephaloceles are often incidental findings, occur in ~5% to 12.5% of individuals,⁵ are not associated with CSF leak, and do not require repair or further monitoring.⁶

Rendering an elegant diagnosis for WX was difficult. Headaches, unsteadiness, visual changes, clumsiness, and slowed cognition could all potentially be related to the encephalocele and CSF leak. However, the abnormal movements would not be expected from these processes. If the movements were entirely due to seizures, the semiology of bilateral shaking would require at least 6 to 10 cm² of cortical involvement with corresponding EEG changes.⁷ However, a typical event was captured on video EEG without epileptiform discharges, indicating at least a component of FNSD A/S. Several possible explanations for WX’s paroxysmal movements remain.

1. FNSD A/S with no epileptic seizures: FNSD A/S may be associated with medical illness⁸ and may resolve with resolution of the illness state,⁹ although this would be the first report of FNSD A/S specifically associated with CSF leak or encephalocele.
2. FNSD A/S associated with focal seizures: As previously mentioned, it is not uncommon for epileptic and nonepileptic events to coexist.⁴ Encephalocele can serve as a seizure focus,⁵ and the olfactory symptom would localize to the medial temporal lobe; in addition, headaches (especially those characteristic of idiopathic intracranial hypertension) are known to be more common peri-ictally when associated with temporal encephaloceles.¹⁰ Whereas FNSD A/S was captured, and the bilateral shaking would not be explained by a focal seizure, coexistent focal seizures cannot be ruled out, given that 17% to 66% of focal seizures cannot be visualized on surface EEG.⁷ Nevertheless, there are no data to support improvement in FNSD A/S after epilepsy surgery, and FNSD A/S is generally considered a relative contraindication to surgery in individuals with known focal refractory epilepsy.¹¹
3. Functional movement disorder associated with CSF leak: Functional movement disorder lies along a spectrum with overlapping symptoms with FNSD A/S.¹² The spasms could potentially be described as a functional hyperkinetic movement. Functional movement disorder has not been reported in association with encephalocele or CSF leak, although other movement disorders, including parkinsonism, chorea, and ataxia, have been reported.¹³

Regardless of etiology, WX’s symptoms resolved completely and suddenly with repair of the CSF leak and associated encephalocele. It is unusual for symptoms to resolve suddenly and completely due to a medical or surgical intervention if they are entirely functional in etiology, a phenomenon most commonly reported with patient acceptance of a psychogenic nonepileptic seizure diagnosis,¹⁴ which WX never received. Thus, this presentation more likely represents resolution of underlying focal seizures with unusual semiology and functional overlay, appearing clinically more like FNSD A/S than typical epileptiform events.

This case illustrates a common occurrence in the epilepsy clinic: an individual with events highly consistent with FNSD A/S, numerous risk factors for FNSD A/S, nonspecific symptoms (headaches, body pain, and dizziness), an incidental MRI finding, and normal EEG results. However, WX was found to have a CSF leak associated with this incidental finding, which was only detected after consultation with otolaryngology. WX’s issues resolved completely after repair of the temporal encephalocele and CSF leak.

FNSD A/S continues to be a common cause for consultation,¹ and providers may dismiss patient concerns given at times challenging interactions¹ and perceptions that management may be outside of the scope of epileptology.¹⁵ The diagnosis of FNSD A/S relies on positive findings incongruous with neurologic functioning. We do not advocate for excessive testing or excluding a structural lesion in all individuals. However, this case illustrates that history-taking and judicious workup of symptoms may identify functional-appearing symptoms obscuring or accompanying another etiology that is curable. This case also highlights that although an encephalocele is a common incidental finding, further investigation with history taking and potential otolaryngology consultation may be warranted, especially if the individual has unusual features that raise clinical concern.