Lesions that involve the tuberoinfundibular region of the hypothalamus are known to cause specific disturbances in sexual function. If such lesions are acquired early in life, pubertal changes may be prevented from occurring. Conversely, with hamartomas of the hypothalamus, as in von Recklinghausen neurofibromatosis and tuberous sclerosis, sexual precocity may occur. Autonomic neuropathies and lesions involving the sacral parts of the parasympathetic system, the most common being prostatectomy, may abolish normal sexual performance but do not alter libido or orgasm.
Blumer and Walker have reviewed the literature on the association of epilepsy and abnormal sexual behavior. They note that sexual arousal, as an ictal phenomenon, is apt to occur in relation to temporal lobe seizures, particularly when the discharging focus is in the mediotemporal region. However, these authors also emphasize the high incidence of global hyposexuality in patients with temporal lobe epilepsy. Temporal lobectomy in such patients has sometimes been followed by a period of hypersexuality.
Acute Fear, Anxiety, Elation, and Euphoria
The phenomena of acute fear and anxiety occurring as a prelude to or part of a seizure is familiar to every neurologist. Williams’s study, already mentioned, is of particular interest; from a series of about 2,000 epileptics, he was able to cull 100 patients in whom an emotional experience was part of the seizure. Of the latter, 61 experienced feelings of fear and anxiety, and 21 experienced depression. Daly has made similar observations. These clinical data call to mind the effects that had been noted by Penfield and Jasper when they stimulated the upper, anterior, and inferior parts of the temporal lobe and cingulate gyrus during surgical procedures; frequently, the patient described feelings of strangeness, uneasiness, and fear. In most instances, consciousness was variably impaired at the same time, and some patients had hallucinatory experiences as well.
In these cortical stimulations, neuronal circuits subserving fear are coextensive with those of anger; both are thought to lie in the medial part of the temporal lobe and amygdala, as discussed earlier. Both in animals and in humans, electrical stimulation in this region can arouse each emotion, but the circuitry subserving fear appears to be located lateral to that of anger and rage. Destruction of the central part of the amygdaloid nuclear complex abolishes fear reactions. These nuclei are connected to the lateral hypothalamus and midbrain tegmentum, regions from which Monroe and Heath, as well as Nashold and associates, have been able to evoke feelings of fear and anxiety by electrical stimulation.
Depression is less frequent as an ictal emotion, although it occurs often enough as an interictal phenomenon (Benson et al). Of interest is the observation that lesions of the dominant hemisphere are more likely than nondominant ones to be attended by an immediate pervasive depression of mood, disproportionate to the degree of severity of physical disability (Robinson et al). It has been challenging, however, to identify the specific neural substrates that are linked with post-stroke depression, and it must also be considered that in many cases depression is a reaction to disability akin to that which follows myocardial infarction. Odd mixtures of depression and anxiety are often associated with temporal lobe tumors and less often with tumors of the hypothalamus and third ventricle (see review by Alpers), and they sometimes occur at the onset of a degenerative disease, such as multiple system atrophy.
Elation and euphoria are less well documented as limbic phenomena, nor has this elevation in mood in some patients with multiple sclerosis ever been adequately explained. Feelings of pleasure and satisfaction as well as “stirring sensations” are unusual, but well-described emotional experiences in patients with temporal lobe seizures. In states of hypomania and mania, every experience may be colored by feelings of delight and pleasure, and a sense of power, and the patient may remember these experiences after he has recovered.
Differential Diagnosis of Perturbations in Emotion and Affect