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Effects of Deep Brain Stimulation on Cognition, Mood, and Behavior in Parkinson’s Disease
adaptation and alterations in medication after surgery. Stimulation in or around Rothlind and co-workers
57
recently reported on a randomized comparison of
the STN has been observed to acutely lead to visual hallucinations,
64
staged, bilateral GPi, and STN DBS in 42 patients and also found that
pseudobulbar crying,
65
laughter and euphoria,
4,66
and depression.
67,68
Acute minimal cognitive changes ensued from the second relative to the first
mood changes are typically provoked by stimulation, dorsal or ventral, to the operation. Semantic verbal fluency (the ability to quickly name items
target for motor symptom control,
69
whereas apathy is associated with ventral belonging to a category such as fruits) declined after left DBS regardless of
and medial STN DBS,
55
hypomania with anteromedial STN DBS,
70
and delusions whether the left side was operated on first or second. Although phonemic
with medial stimulation.
71
Aggression occurs with stimulation in the region of verbal fluency also declined after left DBS only, a significant effect of the
the triangle of Sano,
72
although aggression has also been observed after second surgery was not demonstrated.
stimulation via accurately placed STN electrodes.
73
It is unclear whether GPi DBS is safer than alternative procedures such as
There seems to be a disparity between studies reporting post- pallidotomy or STN DBS. Studies by Merello et al.
15
and Fields et al.
81
found the
operative depression and those using symptom rating scales and self- cognitive safety of GPi DBS and pallidotomy to be comparable. Although some
report inventories showing improvements in mood symptoms. Several suggest that bilateral GPi DBS may entail less cognitive morbidity than bilateral
studies using patient-report inventories have reported improvement in STN DBS,
27,74,82
the only randomized comparison of the cognitive effects of GPi
depressive symptomatology.
16,38,74,75
Similarly, studies disagree as to whether and STN DBS has failed to reveal substantial differences between the two
apathy does or does not increase after STN DBS.
55,76
On the one hand, treatments.
57
A larger randomized trial comparing the effects (including the
studies reporting post-operative incidence of behavioral changes typically neurobehavioral consequences) of simultaneous bilateral GPi with STN surgery
do not report a change from the pre-operative state, leaving it possible that is nearing completion.
83
the incidence of psychiatric conditions actually improves from pre-operative
levels. Indeed, a study has shown that the incidence of psychiatric illness Social Function after Subthalamic Deep Brain Stimulation
may be greater among PD surgical candidates (before surgery) than among Few studies have attended to social adaptation after surgery, a complex
the PD population in general.
77
Alternatively, patients completing inventories matter that has been more adequately addressed in the epilepsy surgery
or responding to questions on rating scales may underestimate or be literature. Recent studies consistently provide evidence that gains in motor
relatively unaware of behavioral changes, as may be indicated by function and quality of life (QOL) do not necessarily translate into improved
discrepancies in the report of patients and their care partners.
38
social integration and adaptation.
84,85
Familial relationships can be
compromised after DBS,
85,86
especially when expectations of outcomes and
A topic of increasing interest has been the phenomenon of pathological perceived levels of functioning diverge between patient and care partner. In
gambling, and isolated cases of this condition have been reported after addition, despite improvements in motor function and QOL, patients may not
DBS.
39,78
A large retrospective study
79
identified seven persons who had return to work. In one study, only nine of 16 with work before surgery had
displayed pathological gambling prior to surgery among 598 patients who returned to work 18–24 months after surgery.
85
Predictors of, and barriers to,
underwent STN DBS. The deleterious urge to gamble lessened after surgery, social adjustment remain to be identified.
resolving on average 18 months after surgery, but the condition of two
patients worsened transiently. An abatement in gambling and other Summary and Conclusions
symptoms of dopamine dysregulation syndrome (e.g. off-period dysphoria, A review of the literature and meta-analyses indicates DBS for movement
non-motor fluctuations) paralleled the course of dopaminergic medication disorders to be quite safe from a neurobehavioral standpoint (while improving
reduction after electrode implantation. Another study of two cases also motor symptoms and both the patient’s and care partner’s QOL). However, it is
reported improvement in pathological gambling after STN DBS and also clear that a small proportion of patients have moderate or severe
concurrent reduction in opaminergic medication.
80
neurobehavioral morbidity. If one combines the various cognitive and
psychiatric morbidities reported across studies, it is reasonable to estimate that
Comparisons of Unilateral versus Bilateral and about 10% of patients with PD undergoing DBS will experience one or more
Pallidal versus Subthalamic Deep Brain Stimulation transient or permanent neurobehavioral adverse events. Deserving detailed
To determine whether second surgery (i.e. a staged bilateral procedure) carries empirical investigation is the observation in a few small uncontrolled studies
cognitive risks relative to the first surgery, Fields et al.
21
examined that improvements in motor symptoms and QOL may not necessarily translate
neuropsychological functioning in six patients before surgery, two months after into social (re)adjustment. Research will need to identify the patient, medico-
the first GPi DBS operation, and again three months after the second surgical, and psychosocial factors that are associated with neurobehavioral
operation. No patient experienced significant declines in cognition and delayed morbidity and preclude some patients from demonstrating gains in
recall was improved relative to baseline following the second operation. occupational, interpersonal, familial, and marital functioning. ■
1. Hassler R, Riechert T, Mundinger F, et al., Brain, 6. Mayberg HS, Lozano AM, Voon V, et al., Neuron, 11. Loher TJ, Gutbrod K, Fravi NL, et al., J Neurol,
1960;83:337–50. 2005;45(5):651–60. 2003;250(6):707–13.
2. Siegfried J, Lippitz B, Stereotact Funct Neurosurg, 7. Nuttin B, Cosyns P, Demeulemeester H, et al., Lancet, 12. Woods SP, Fields JA, Lyons KE, et al., Acta Neurochirurgica,
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3. Benabid AL, Pollak P, Louveau A, et al., Appl Neurophysiol, 8. Parsons TD, Rogers SA, Braaten AJ, et al., Lancet Neurol, 13. Vingerhoets G, van der Linden C, Lannoo E, et al., J Neurol
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4. Benabid AL, Koudsié A, Benazzouz A, et al., J Neurol, 9. Caparros-Lefebvre D, Blond S, Pécheux N, et al., Revue 14. Tröster AI, Fields JA, Wilkinson SB, et al., Neurology,
2001;248(Suppl. 3):37–47. Neurologique, 1992;148(2): 117–22. 1997;49(4):1078–83.
5. Benabid AL, Minotti L, Koudsie A, et al., Neurosurgery, 10. Tröster AI, Fields JA, Wilkinson SB, et al., Neurosurg 15. Merello M, Nouzeilles MI, Kuzis G, et al., Mov Disord,
2002;50(6):1385–91, discussion 1391–2. Focus,1997;2(3):1–6. 1999;14(1):50–56.
US NEUROLOGY 71
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