Sleep-Related Painful Erections

Gilles Karsenty; Esther Werth; Peter A. Knapp; Armin Curt; Brigitte Schurch; Claudio L. Bassetti


Nat Clin Pract Urol. 2005;2(5):256-260. 

In This Article

Discussion of Diagnosis

The patient was referred with the unusual diagnosis of intermittent nocturnal priapism. Highflow priapism presents as intermittent and prolonged partial erections, but is usually painfree. The following potential diagnoses for erectile pain were therefore considered: low-flow priapism, Peyroniefs disease, PHIMOSIS, urethritis1 and metastasis of miscellaneous carcinoma (prostate, bladder or lung) into the corpora cavernosa. None of these conditions, however, are clearly related to sleep. By definition, low-flow priapism lasts > 4 h, does not stop spontaneously, and is independent of sleep (except for a theoretical sickle cell anemia crisis triggered by hypoxemia during a sleepapnea period). Moreover, untreated or recurrent low-flow priapism leads to severe fibrotic damage of the corpora cavernosa and loss of erectile function, which was not the case in our patient despite a 3-year history of the disorder. Peyroniefs disease, phimosis and urethritis1 produce a clearly distinct clinical profile compared with sleep-related painful erections, with painful erection occurring during all erectile episodes, not only sleep-related ones. The earliest and most marked symptom of tumor metastasis to the corpora cavernosa is often penile pain independent of erection. Bulky metastases can mimic permanent rigidity and also produce erosion of penile vessels leading to highflow priapism, but symptoms are independent of sleep, and clinical and sonographic examinations are abnormal.

After referral to the neurology department, the diagnosis of sleep-related painful erections was suggested. Polysomnography coupled with nocturnal penile tumescence recording confirmed this diagnosis, documenting recurrent awakenings, mostly after REM sleep, accompanied by painful erections. Painless erections appeared during periods of wakefulness and non-REM sleep.

According to the International Classification of Sleep Disorders,[2] sleep-related painful erections are characterized by penile pain during sleep-related erections, typically during REM sleep, contrasting with painless erections in the awake state. Associated symptoms include repeated awakenings, sleep loss and daytime anxiety, tension and irritability. Sleep-related painful erections have never been reported in the English-language urological literature and might be unknown to the majority of urologists. Since the first description by Karacan in 1971,[3] 25 cases of sleep-related painful erections have been reported in the English-language neuro logical literature, in five single-case reports,[3–7] one three-case series[8] and in a mono- institutional series of 17 consecutive patients.[9]

Sleep-related painful erections are thought to occur in < 1% of patients presenting with sexual and erectile problems.9 As suggested by Calvet, however, the rarity of the published observation might not reflect the actual frequency of the disorder.8 Ferini-Strambi et al. estimated the frequency of sleep-related painful erections to be 2% (17/825) of the patients referred to their sleep laboratory for nocturnal penile tumescence monitoring during a 6-year period.9 Because not all patients with sexual or erectile dysfunction are referred to a sleep laboratory,10 the actual prevalence of sleep-related painful erections among patients seeking first-line urological advice is likely to be lower. In all reported cases, patients fulfilled the main International Classification of Sleep Disorders criteria. Although the most frequently associated symptom was anxiety, psychiatric evaluation of the patients showed that sleep-related painful erections are not associated with any psychiatric diagnoses.[3,5,8,9] Ferini-Strambi et al. reported associated erectile dysfunction (impaired awake-state erections) in 23% of their patient series, but all of these patients had coexisting fully rigid nocturnal erection recordings.[9] Such erectile dysfunction was most likely psychogenic, and related to sleep loss and anxiety. Anatomical abnormalities of the penis were always absent.

Neurological examination was normal in all reported cases, as were neurophysiological tests (somatosensory cortical-evoked potential and bulb-cavernous reflex latency). Only one case was potentially related to a neurological condition: a compression of the anterolateral surface of the hypothalamus by the posterior cerebral artery discovered on a brain MRI.[6]

In all reported cases, diagnosis was confirmed by polysomnography coupled with a penile tumescence recording. Polysomnography typically demonstrated fragmented sleep, mostly during REM phases. Painful erections occurred mostly but not exclusively during REM sleep,[8,9] which is not surprising given that 80% of erection time occurs during REM sleep, and every nocturnal erection cycle is typically generated in association with a corresponding REM period.[10]

The overall mean age at onset of sleep-related painful erections for all reported cases was 40 years. All patients presented with a chronic, and in the majority of cases severe (episodes every night or more than once per night), form of the disorder.[9] The mean delay between onset and diagnosis was approximately 5 years (range 1–20 years), and in most reported cases there was a history of several unsuccessful consultations with urologists and neurologists.

No clear predisposing factors or familial patterns for sleep-related painful erections have been identified. Etiologic hypotheses are scarce, ranging from autonomic nervous system disturbance with beta-adrenergic hyperactivity during sleep,[11] to local disturbance of neurotransmission[4,8] or damage or stimulation of the anterior hypothalamus.[6] Although this last hypothesis is supported by just one clinical case, it is in line with current understanding that sleep-related erections are controlled by the lateral pre-optic area of the hypothalamus.[10]

To our knowledge, this case study might represent the second published case of symptomatic sleep-related painful erections of neurological origin,[6] although the causal relationship with the thoracic ependymoma remains uncertain for two main reasons. First, there was a 2-year event-free interval between removal of the spinal cord lesion and the onset of symptoms; moreover, during this interval no changes in neurological status or radiological evidence for recurrence of the initial lesion or for evolution of the surgical after-effect lesion were detected. Second, although spinal cord regulation is thought to be critical for nocturnal erection activity (the presence or absence of erections depending on the level of a complete spinal cord lesion),[12] sleep-related painful erections have never been reported in patients with complete or incomplete spinal cord injuries.


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