Neuropsychiatric Symptoms of Epilepsy

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G. Rayner and S.J. Wilson
became free of both epileptogenic and psychogenic seizures, two became free of epileptic
seizures but continued to have infrequent psychogenic seizures, one reported
major improvement in epileptogenic seizures and cessation of psychogenic attacks,
and in one patient nondisabling epileptogenic seizures persisted at lower frequency
but psychogenic seizures ceased. This study provides preliminary evidence that epilepsy
surgery may have a beneficial impact on comorbid PNES, although the psychological
or neurobiological mechanisms underpinning remission remain unclear.
The successful surgical treatment of epilepsy occasionally has a paradoxical outcome,
namely, the development of PNES after surgery, including in patients who
achieve good seizure control [ 100 ]. A study by Davies et al. ([101]; N=228) estimates
a 3.5 % incidence of de novo PNES after surgery, with symptoms emerging anywhere
between 6 weeks to 6 years after the procedure ( M = 23 weeks). PNES is the most
widely studied somatic symptom disorder in the epilepsy literature. Such disorders are
heterogeneous; however, in a unique addition to the literature Naga et al. [ 102 ] identified
10 patients who developed somatic symptom disorders other than PNES from a
cohort of 450 patients with surgically remediable epilepsy (i.e., a prevalence rate of
2.2 %). After surgery, seven patients developed an undifferentiated somatic symptom
disorder, one developed a pain disorder, one developed body dysmorphia, and one
developed a combined pain disorder and body dysmorphia. All of the patients had
undergone an ATL and nine had a right-lateralized resection, providing preliminary
neurobiological evidence for the role of the right temporal lobe in emotional regulation
and the interpretation and attribution of somatic sensations and perceptions.
Risk Factors for Somatic Symptom Disorders After Epilepsy
Surgery
Risk factors for the development of PNES after epilepsy surgery include a preexisting
neuropsychiatric disorder, physical complications from surgery (such as a bone
flap infection), and low IQ [ 100 , 101 ]. Females are again overrepresented, with 8.5
% of female patients with a preoperative psychiatric diagnosis developing PNES
after surgery [ 103 ]. These risk factors suggest that de novo PNES after epilepsy
surgery might be more prevalent in female patients who have diminished psychological
or cognitive resources to cope with a serious physical complication of surgery
or to manage the often complex process of adjustment that underpins the
patient’s transition from chronically ill to suddenly well.
The neurobiological importance of the right hemisphere in the emergence of
somatic symptom disorders after surgery is supported by a study comparing 79
consecutive patients with PNES to 122 patients with epileptogenic seizures.
Seventy-six percent of the PNES patients in this cohort had unilateral cerebral
abnormalities on neuroimaging, of which 71 % were in the right hemisphere [ 104 ].
Together, these studies support the longstanding hypothesis that the right hemisphere
is preferentially involved in the perception and processing of emotions and,
when dysfunctional, fails to facilitate the acceptance of traumatic emotions and