Hard flaccid syndrome | |
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A penis in the "hard flaccid" state | |
Specialty | Urology, sexual medicine, neurology, men's health |
Symptoms | A flaccid penis that remains in a firm, semi-rigid state in the absence of sexual arousal |
Usual onset | Typically following a traumatic event (an injury to the erect penis, blunt perineal trauma, cauda equina) though can also appear without an apparent cause |
Causes | Excessive sympathetic activity in the erectile smooth muscle tissue |
Risk factors | Aggressive or prolonged masturbation, rough or prolonged intercourse, practicing penis enlargement techniques, bicycle riding, horseback riding, annular tears, tarlov cysts; other risk factors currently unknown |
Diagnostic method | Overwhelmingly self-diagnosed |
Treatment | Definitive treatment does not currently exist |
Hard flaccid syndrome (HFS), also known as hard flaccid (HF), is a rare acquired dysautonomic condition characterized by a flaccid penis that remains in a firm, semi-rigid state in the absence of sexual arousal. Patients often describe their flaccid penis as firm to the touch, rubbery, shrunken, and retracted, frequently accompanied by pain, discomfort, and various other symptoms. [1] [2] [3] [4] [5] [6] [7] While the condition is not fully understood, current research indicates that HFS results from excessive sympathetic nervous system activity in the smooth muscle tissue of the penis, triggered by a pathological activation of a proposed pelvic/pudendal-hypogastric reflex. [1] Among other causes, injuries to the erect penis, blunt trauma to the pelvis or perineum, and damage to the cauda equina are thought to induce this reflex. [1] Although unproven, it is possible that axon sprouting in sympathetic ganglia following a peripheral nerve injury is the true explanation for HFS. [8] [9] The majority of patients are in their 20s and 30s, with symptoms severely affecting their quality of life. [1] [2] [4] [3] [5] Treatment typically involves a combination of alpha blockers and PDE5 inhibitors, although there is limited evidence supporting their efficacy. [6] [7] Due to the lack of comprehensive understanding and awareness within the scientific and medical communities, there is currently no definitive treatment for HFS.
The most obvious, unmistakable, and defining symptom of hard flaccid syndrome is a penis that remains in a firm, semi-rigid state in the absence of sexual arousal. The flaccid penis will appear shrunken, contracted, and upon palpation will feel hard and non-compressible. [1] This typically worsens when the patient is in a standing position. [1] The skin on the shaft of the flaccid penis may also have folds or wrinkles, resembling gastric and vaginal rugae. [8]
In addition to a "hard flaccid" penis, patients may also experience erectile dysfunction (difficulty achieving or maintaining an erection; painful or tight erections; penis does not fill up completely when getting an erection; no morning erections; no nocturnal erections; no spontaneous erections; painful nocturnal erections), sensory changes (a persistent feeling of coldness in the glans, shaft, or entire penis; paresthesia or pins and needles in or around the penis; dysesthesia or an unpleasant, abnormal sense of touch in or around the penis; complete or partial loss of erogenous sensation to the penis; complete or partial loss of tactile feeling to the penis including temperature, pressure, vibration, or texture; penis feels "hollow", "disconnected" or unstable, as if it was not a part of the body), physical or structural changes to the penis (an hourglass or bottleneck shape to the penis during the flaccid or semi-erect states; engorged veins or spider veins; discoloration of the skin of the penis; soft glans; "long flaccid", where the flaccid penis is more extended than it should be and either feels firm or like a balloon filled with water; tilt of the penis to one side while flaccid, erect, or both; rotation of the penis when erect), pain (pain in or around the penis; pain in or around the penis or perineum after ejaculation), testicular retraction, urinary issues (incontinence; urgency; duel urine streams; a burning feeling when urinating), pelvic floor dysfunction, and constipation. [1] [2] [3] [4] [5] [6] [7]
Although not fully understood, the general consensus is that hard flaccid syndrome is caused by elevated sympathetic nervous system activity, or tone, in the penis following a peripheral nerve injury. This heightened activity leads to an excessive release of norepinephrine in the erectile smooth muscle tissue, causing relentless smooth muscle contraction, which produces the "hard flaccid" state, or the persistent firmness and semi-rigidity of the flaccid penis that is characteristic of the condition. [1] The temporary resolution of the "hard flaccid" state through intracavernous injections of phentolamine, an α-adrenergic antagonist, supports this claim. [1] HFS resembles a condition called complex regional pain syndrome (CRPS) in its presentation, as both are thought to arise from an isolated injury that triggers a pathological shift in nervous system activity, amplifying pain signals and symptoms beyond that of the original trauma.
In May 2023, Dr. Irwin Goldstein of San Diego Sexual Medicine and colleagues published an article in AUA News presenting a theory on the pathophysiology of hard flaccid syndrome. They hypothesized that the condition results from excessive sympathetic activity in the hypogastric nerve, induced by a pathological activation of a pelvic/pudendal-hypogastric reflex. [1] The authors identified five potential anatomical sites where this reflex could be triggered:
In a June 2024 interview with Stefan Buntrock on the "UroChannel" YouTube channel, Dr. Goldstein discussed region one pathology, stating, “I believe that’s the vast majority of cases,” suggesting that penile injuries are the primary cause of hard flaccid syndrome in most patients. [8]
This is still considered the prevailing theory for the pathophysiology of hard flaccid syndrome.
Region one pathology involves the end organ, or penis. Traumatic events or injuries to the erect penis are believed to trigger HFS in these cases. Region one is considered the most common pathology in patients with HFS. [1] [8]
Potential triggers:
Region two pathology involves the pelvic or perineal area. In these cases, the condition is likely attributed to pudendal nerve neuropathy. [1]
Potential Triggers:
Region three pathology involves the cauda equina, a cluster of spinal nerves at the lower end of the spinal cord, responsible for transmitting signals between the lower body and the brain. Pathological activation in this area can result from structural issues, including disc protrusions, Tarlov cysts, and annular tears. These can compress or irritate the cauda equina, and potentially lead to HFS. Patients with region three pathology typically show limited response to treatment, but some have experienced significant improvement or even full recovery following spinal surgery. [1]
Potential triggers:
Region four pathology involves the spinal cord. [1]
Region five pathology involves the brain. [1]
In his June 2024 interview with Stefan Buntrock on the "UroChannel" YouTube channel, Dr. Irwin Goldstein discussed the potential link between hard flaccid syndrome and sympathetic axon sprouting. He referenced a study where injury to the sciatic nerve in rats led to sympathetic axon sprouting in the dorsal root ganglia. If applicable to HFS, damage to the pelvic and/or pudendal nerves could induce similar sprouting in sympathetic ganglia. Dr. Goldstein remarked, “The idea of this sprouting is making more sense as the real explanation for this, because once it sprouts, I don’t know how you’re supposed to stop that.” [8] [9]
At present, there is no formalized schema or method for diagnosing hard flaccid syndrome in a clinical environment. [8] [10] Due to the condition's relative obscurity within the medical community, the majority of HFS patients diagnose themselves. [1]
Definitive treatment for hard flaccid syndrome does not exist and current methods often fail to relieve symptoms for most patients. [6] [7] The complexity and poorly understood nature of HFS makes it very difficult to treat. [11] As a result, there is a growing need for more research that can provide better outcomes for those suffering from this challenging condition.
The perineum in placental mammals is the space between the anus and the genitals. The human perineum is between the anus and scrotum in the male or between the anus and vulva in the female. The perineum is the region of the body between the pubic symphysis and the coccyx, including the perineal body and surrounding structures. The perineal raphe is visible and pronounced to varying degrees.
The pudendal nerve is the main nerve of the perineum. It is a mixed nerve and also conveys sympathetic autonomic fibers. It carries sensation from the external genitalia of both sexes and the skin around the anus and perineum, as well as the motor supply to various pelvic muscles, including the male or female external urethral sphincter and the external anal sphincter.
Penis enlargement, or male enhancement, is any technique aimed to increase the size of a human penis. Some methods aim to increase total length, others the shaft's girth, and yet others the glans and foreskin size. Techniques include surgery, supplements, ointments, patches, and physical methods like pumping, jelqing, and traction.
Tetraplegia, also known as quadriplegia, is defined as the dysfunction or loss of motor and/or sensory function in the cervical area of the spinal cord. A loss of motor function can present as either weakness or paralysis leading to partial or total loss of function in the arms, legs, trunk, and pelvis. The paralysis may be flaccid or spastic. A loss of sensory function can present as an impairment or complete inability to sense light touch, pressure, heat, pinprick/pain, and proprioception. In these types of spinal cord injury, it is common to have a loss of both sensation and motor control.
The cauda equina is a bundle of spinal nerves and spinal nerve rootlets, consisting of the second through fifth lumbar nerve pairs, the first through fifth sacral nerve pairs, and the coccygeal nerve, all of which arise from the lumbar enlargement and the conus medullaris of the spinal cord. The cauda equina occupies the lumbar cistern, a subarachnoid space inferior to the conus medullaris. The nerves that compose the cauda equina innervate the pelvic organs and lower limbs to include motor innervation of the hips, knees, ankles, feet, internal anal sphincter and external anal sphincter. In addition, the cauda equina extends to sensory innervation of the perineum and, partially, parasympathetic innervation of the bladder.
Sciatica is pain going down the leg from the lower back. This pain may go down the back, outside, or front of the leg. Onset is often sudden following activities such as heavy lifting, though gradual onset may also occur. The pain is often described as shooting. Typically, symptoms are only on one side of the body. Certain causes, however, may result in pain on both sides. Lower back pain is sometimes present. Weakness or numbness may occur in various parts of the affected leg and foot.
Sexual dysfunction is difficulty experienced by an individual or partners during any stage of normal sexual activity, including physical pleasure, desire, preference, arousal, or orgasm. The World Health Organization defines sexual dysfunction as a "person's inability to participate in a sexual relationship as they would wish". This definition is broad and is subject to many interpretations. A diagnosis of sexual dysfunction under the DSM-5 requires a person to feel extreme distress and interpersonal strain for a minimum of six months. Sexual dysfunction can have a profound impact on an individual's perceived quality of sexual life. The term sexual disorder may not only refer to physical sexual dysfunction, but to paraphilias as well; this is sometimes termed disorder of sexual preference.
Pudendal nerve entrapment (PNE) is an uncommon, chronic pelvic pain condition in which the pudendal nerve is entrapped and compressed. There are several different anatomic locations of potential entrapment. Pudendal nerve entrapment is an example of nerve compression syndrome.
A discectomy is the surgical removal of abnormal disc material that presses on a nerve root or the spinal cord. The procedure involves removing a portion of an intervertebral disc, which causes pain, weakness or numbness by stressing the spinal cord or radiating nerves. The traditional open discectomy, or Love's technique, was published by Ross and Love in 1971. Advances have produced visualization improvements to traditional discectomy procedures, or endoscopic discectomy. In conjunction with the traditional discectomy or microdiscectomy, a laminotomy is often involved to permit access to the intervertebral disc. Laminotomy means a significant amount of typically normal bone is removed from the vertebra, allowing the surgeon to better see and access the area of disc herniation.
Sexual medicine or psychosexual medicine as defined by Masters and Johnsons in their classic Textbook of Sexual Medicine, is "that branch of medicine that focuses on the evaluation and treatment of sexual disorders, which have a high prevalence rate." Examples of disorders treated with sexual medicine are erectile dysfunction, hypogonadism, and prostate cancer. Sexual medicine often uses a multidisciplinary approach involving physicians, mental health professionals, social workers, and sex therapists. Sexual medicine physicians often approach treatment with medicine and surgery, while sex therapists often focus on behavioral treatments.
Cauda equina syndrome (CES) is a condition that occurs when the bundle of nerves below the end of the spinal cord known as the cauda equina is damaged. Signs and symptoms include low back pain, pain that radiates down the leg, numbness around the anus, and loss of bowel or bladder control. Onset may be rapid or gradual.
The conus medullaris or conus terminalis is the tapered, lower end of the spinal cord. It occurs near lumbar vertebral levels 1 (L1) and 2 (L2), occasionally lower. The upper end of the conus medullaris is usually not well defined, however, its corresponding spinal cord segments are usually S1–S5.
The sacrotuberous ligament is situated at the lower and back part of the pelvis. It is flat, and triangular in form; narrower in the middle than at the ends.
Pelvic pain is pain in the area of the pelvis. Acute pain is more common than chronic pain. If the pain lasts for more than six months, it is deemed to be chronic pelvic pain. It can affect both the male and female pelvis.
Pelvic splanchnic nerves or nervi erigentes are splanchnic nerves that arise from sacral spinal nerves S2, S3, S4 to provide parasympathetic innervation to the organs of the pelvic cavity.
In human anatomy, the penis is an external sex organ through which males urinate and ejaculate. Together with the testes and surrounding structures, the penis functions as part of the male reproductive system.
An erection is a physiological phenomenon in which the penis becomes firm, engorged, and enlarged. Penile erection is the result of a complex interaction of psychological, neural, vascular, and endocrine factors, and is often associated with sexual arousal, sexual attraction or libido, although erections can also be spontaneous. The shape, angle, and direction of an erection vary considerably between humans.
Human penis size varies on a number of measures, including length and circumference when flaccid and erect. Besides the natural variability of human penises in general, there are factors that lead to minor variations in a particular male, such as the level of arousal, time of day, ambient temperature, anxiety level, physical activity, and frequency of sexual activity. Compared to other primates, including large examples such as the gorilla, the human penis is thickest, both in absolute terms and relative to the rest of the body. Most human penis growth occurs in two stages: the first between infancy and the age of five; and then between about one year after the onset of puberty and, at the latest, approximately 17 years of age.
Nerve compression syndrome, or compression neuropathy, or nerve entrapment syndrome, is a medical condition caused by chronic, direct pressure on a peripheral nerve. It is known colloquially as a trapped nerve, though this may also refer to nerve root compression. Its symptoms include pain, tingling, numbness and muscle weakness. The symptoms affect just one particular part of the body, depending on which nerve is affected. The diagnosis is largely clinical and can be confirmed with diagnostic nerve blocks. Occasionally imaging and electrophysiology studies aid in the diagnosis. Timely diagnosis is important as untreated chronic nerve compression may cause permanent damage. A surgical nerve decompression can relieve pressure on the nerve but cannot always reverse the physiological changes that occurred before treatment. Nerve injury by a single episode of physical trauma is in one sense an acute compression neuropathy but is not usually included under this heading, as chronic compression takes a unique pathophysiological course.