Differentiating between impulsivity and compulsivity and differentiating between disorders that are related to impulsive or compulsive behaviors may help optimize treatment for reducing psychiatric symptoms that may occur following a cerebral infarction. Repetitive behavior can occur in many disorders or conditions, such as frontal syndrome [6], punding [7] or obsessive-compulsive disorder (OCD) [8], but also in autism spectrum disorders and tic disorders [9]. The differentiation between these conditions is not always clear-cut due to phenomenological similarities between impulsivity and compulsivity. For example, where punding is defined as repetitive, meaningless compulsive behavior, this is also characteristic for OCD symptoms. And as frontal syndrome can often occur following infarction, compulsive symptoms may incorrectly be confused with impulsivity related to frontal syndrome.

In the course of a few years, despite a physical and cognitive revalidation program, the cognitive impairments did not improve, and even though most of the disinhibition disappeared, the whistling persisted.

We were approached in May 2008 by the patient’s wife, who got to know our center of expertise through the internet. She was close to desperation from listening to the whistling of the same carnival song for nearly 16years. It would go on for 5 to 8 hours every day and got worse when the patient was tired. He had been treated with clomipramine 150mg/day for nearly two months which resulted in a 50% decrease of compulsive whistling (3–4 hours a day), however, with urinary incontinency as an unacceptable side effect. Subsequent treatment with paroxetine 20mg/day resulted in only a slight relief of the symptoms with similar side effects as with clomipramine.

Firstly, the repetitive whistling may have a merely impulsive nature with disinhibitive behavior. In that perspective, the whistling may be attributed to a frontal syndrome. This syndrome was observed immediately following the cardiac arrest and resulted in a limited period of sexually disinhibited behavior and spitting. The clinical features of the frontal syndrome showed similarities with frontotemporal dementia that is also characterized by disinhibition and actions without foresight of the consequences, such as increased risk-taking behavior [6] and sometimes compulsions with the inability to inhibit repetitive, irresistible urges to perform behavior [10]. Frontal syndrome is associated with structural lesions in the frontal brain areas. Interestingly, simple compulsive behaviors (such as verbal and motor repetitions) seem to correlate with striatal dysfunction, whereas more complex (intentional or time-consuming) behaviors seem to be related to frontal and temporal lobe atrophy, probably reflecting dysfunctional suppression of compulsive thoughts and behaviors [11]. This is in line with the finding that orbitofrontal-basal ganglia dysfunction is associated with OCD [8,12]. In our case, it is unlikely that the whistling is part of a frontal syndrome solely, since it persisted long after the typical disinhibition symptoms spontaneously remitted. The whistling may also be merely impulsive, stereotypic behavior and occur as a stand-alone symptom following brain damage. However, stereotypies are not accompanied with premonitory urges, internal desire to perform and relief from these urges [13]. As our patient clearly feels anxious when stopped and feels the urge to perform, this is not likely to be stereotypic behavior alone.

Another possibility is that the repetitive whistling may be understood in the context of compulsivity and may be associated with punding. Punding is characterized by purposeless and repetitive behavior, such as collecting or arranging things [7,14] often related to the patients’ personal hobbies or occupation and attributed to alterations of the brain’s reward and motor systems in both the ventral and the dorsal striatum [15]. Several aspects of the compulsive whistling show similarities with punding: its repetitive and somewhat comforting character, the irritability and dysphoria when interruption was attempted, and the fact that our patient used to like singing this song in his role as head of a carnival association. Mostly, punding is associated with dopamine dysregulation syndrome (DDS) and occurs as a consequence of therapy with dopamine agonists. More specifically, the punding phenomenon is directly related to a dopamine dysregulation with a clear link to dopamine agonists and L-dopa addictive behavior. A relation with drugs that interact with serotonin receptors, such as quetiapine, have occasionally been found to induce punding [15]. However, sometimes punding is not directly related to chemical induction or hypersensitivity, but more closely related to structural abnormalities. One particular case of compulsive singing as part of dopamine dysregulation syndrome in Parkinson’s disease shows a striking clinical resemblance with our case [15]. Nguyen et al. [16] reported a case in which punding was observed after infarction.

One may hypothesize, thirdly, that the repetitive whistling has a compulsive character and may be originated in the development of OCD. Specific lesions are known to be involved in OCD, such as frontal regions and the basal ganglia. OCD has been related to a decreased volume in these areas, to abnormal neuronal activity in the orbitofrontal cortex, the anterior cingulate, the dorsolateral prefrontal cortex, the caudate nucleus and the thalamus [8]. Also dysfunctional neurotransmitter pathways [17] are suggested to be involved, specifically serotonergic, dopaminergic and glutaminergic pathways with serotonergic reuptake inhibitors (SRIs) as first-line treatment in OCD and tricyclic antidepressants (TCAs), in particular clomipramine, proved to be effective. Typically, obsessive-compulsive symptoms start gradually, early in life and persist. They do not frequently occur following an infarct. Some case studies, however, report a late and sudden onset of OCD symptoms following an organic etiology in which orbitofrontal areas and/or basal ganglia are harmed [18-20]. Like idiopathic OCD, acquired OCD after brain injuries often responds well to SRI treatment [19,21], which was true for our case. Some other studies however, show less successful treatment outcome [22,23]. Our patient did not suffer from typical anxiety symptoms of OCD, however, anxiety is often lacking in other cases of acquired OCD after brain injuries and may be more of a secondary phenomena in OCD. Finally, this particular case does not present with obsessions that are usually preceding compulsive behaviors in OCD.

This case of repetitive whistling shows similarities with a frontal syndrome, punding and OCD. However, it does not fit all features of these diagnoses and may be present as an independent symptom. Furthermore, one may conclude that the whistling with its repetitions is primarily compulsive rather than impulsive or disinhibitive, as the patient had a constant urge to whistle and felt anxiety when asked to stop rather than acting without foresight. The fact that anxiety was felt is in line with compulsivity rather than impulsivity, assuming that compulsive behaviors are performed to prevent perceived negative consequences to happen [4]. In impulsivity, the tendency to act prematurely without foresight would be more prominent and anxious feelings are not necessarily present in impulsive behaviors with diminished regard to negative consequences. Interestingly, not only OCD but also punding [15] and features of frontal syndrome, i.e. frontotemporal dementia [10] may show compulsive symptoms that are attributed to disturbances in the cortico-striatal pathway.

The current case shows that clomipramine decreased the repetitive whistling. Interestingly, SRIs may be effective in alleviating symptoms of compulsivity in idiopathic [17] and acquired [19,21] OCD, frontal syndrome [24] and punding [15]. This suggests that compulsive symptoms may be effectively treated with SRIs or TCAs, even when compulsivity occurs as a stand-alone symptom.