The internal urethral sphincter (smooth muscle tissue) or the external urethral sphincter (striated muscle), levator ani (especially the pubococcygeus) muscle area, or some combination of the above, may be involved. It is possible that there is an inhibition of the detrusor command through a reflex pathway as well. The pontine micturition center (Barringtons nucleus) also may be involved, as its inhibition results in relaxation of the detrusor and prevents the relaxation of the internal sphincter. Diagnosis
The condition is catered for in the rules for mandatory urine testing for drugs in UK prisons, and UK Incapacity Benefit tribunals also recognise it. It is listed in the NHS on-line encyclopaedia of conditions and disorders. It is now reported to have been accepted as a valid reason for jury service excusal. From 1 August 2005, the guidance on the rules relating to the testing of those on probation in the UK cites paruresis as a valid reason for inability to produce a sample which is not to be construed as a refusal.The condition is recognised by the American Urological Association, who include it in their on-line directory of conditions.Paruresis was described in section 300.23 of the DSM-IV-TR as "performance fears . . . using a public restroom" but it was not mentioned by name.
Brachioradial pruritus (sometimes abbreviated BRP) is an intense itching sensation of the arm usually between the wrist and elbow of either or both arms. : 36   The itch can be so intense that affected individuals will scratch their own skin to a bleeding condition. The condition is becoming increasingly common, presenting in patients who are usually fair skinned and middle aged and indulge in golf, tennis, outdoor table tennis, sailing,  or other leisure outdoor activities in sunny climates. : 64 : 402 The cause is not known, although there are a few lines of thought on what causes it. No cure has been found, but depending on severity, good control with treatment can be achieved. For milder cases, the intense itch/scratch cycle can be broken by applying a topical skin coolant gel containing menthol, camphor, or other topical coolant to affected itchy areas, and then consistently applying 100+SPF sunscreen to affected skin of arms, shoulders, neck, etc., whenever they are expected to be exposed to the sun. A unique prescription topical combination of ketamine .5% and amitriptyline hydrochloride 1% has shown immediate and long term relief with no serious adverse events in at least one severe case. [1]
Many different medications and types of topical creams have been experimented with, but few seem to make any difference, except for the above. The application of ice packs to the affected area can also diminish the itch short-term. Causes
Brachioradial pruritus (BRP) is a localized pruritus of the dorsolateral aspect of the arm.