Aetiology

Aetiology of erectile dysfunction can be:

• psychogenic
  • history of sexual abuse, marital or relationship stress
  • performance anxiety
  • overt psychological disorders, such as depression or schizophrenia
  • drugs prescribed to treat psychological disorders
• organic
  • vascular
    • cardiovascular disease
    • artherosclerosis
    • hypertension
    • diabetes
    • hyperlipidaemia
    • smoking
    • major surgery or radiotherapy (pelvis or retroperitoneum)
  • neurogenic
    • central causes
      • degenerative disorders (multiple sclerosis, Parkinson’s disease, multiple atrophy etc.)
      • spinal cord trauma or diseases
      • stroke
      • CNS tumors
    • peripheral causes
      • type 1 and 2 diabetes mellitus
      • chronic renal failure’
      • polyneuropathy
      • surgery e.g - pelvis or retroperitoneum, radical prostatectomy, colorectal surgery, etc.)
  • anatomical or structural
    • foreskin problems (phimosis, lichen sclerosus)
    • penile curvature (congenital curvature or Peyronie’s disease)
    • benign and malignant genital dermatoses.
  • hormonal
    • hypogonadism
    • hyperprolactinemia
    • hyper- and hypothyroidism
    • hyper- and hypocortisolism (Cushing’s disease etc.)
  • drug induced
    • antihypertensives (diuretics are the most common medication causing ED)
    • antidepressants (selective serotonin reuptake inhibitors, tricyclics)
    • antipsychotics (incl. neuroleptics)
    • antiandrogens; GnRH analogues and antagonists
    • recreational drugs (alcohol, heroin, cocaine, marijuana, methadone)

However, in most patients both factors probably contribute to the failure to achieve an adequate erection.

Notes:

• head injury and gonadotropin deficiency (3)
  • marked changes of the hypothalamo-pituitary axis have been documented in the acute phase of traumatic brain injury(TBI)
    • following TBI as many as 80% of patients showing evidence of gonadotropin deficiency, 18% of growth hormone deficiency, 16% of corticotrophin deficiency and 40% of patients demonstrating vasopressin abnormalities leading to diabetes insipidus or the syndrome of inappropriate anti-diuresis
    • longitudinal prospective studies have shown that some of the early abnormalities are transient, whereas new endocrine dysfunctions become apparent in the post-acute phase. There remains a high frequency of hypothalamic-pituitary hormone deficiencies among long-term survivors of TBI, with approximately 25% patients showing one or more pituitary hormone deficiencies

Reference:

• (1) Muneer A et al. Erectile dysfunction. BMJ. 2014;348:g129
• (2) European Association of Urology (2014). Guidelines on Male Sexual Dysfunction: Erectile dysfunction and  premature ejaculation
• (3) Behan LA et al. Neuroendocrine disorders after traumatic brain injury. J Neurol Neurosurg Psychiatry. 2008 Jul;79(7):753-9