According to Vilanora and Raventos, in 1954, a fourth group called pseudodiphallia is added.The current widely accepted classification, introduced by Aleem in 1972, classifies double penis into two groups: true diphallia and bifid phallus. True diphallia is caused by cleavage of pubic tubercle; bifid phallus is caused by separation of pubic tubercle. Each of these two groups is further subdivided into partial or complete. True diphallia is where each phallus has two corpora cavernosa and a single corpus spongiosum containing a urethra. True diphallia can be either complete with both penises similar in size, or partial when one of the phallia is smaller in size or immature, though structurally same as the larger phallus. In bifid phallus, each phallus has only one corpus cavernosum and one corpus spongiosum containing a urethra. Separation of penises down to the base of the penile shaft is complete bifid, whereas to glans is partial bifid. For complete bifid phallus associated with anomalies, the anterior urethra is absent from each penis and the prostatic urethra is situated in the skin between the two penises. In partial bifid phallus, the duplication of urethra, corpora cavernous and corpus spongiosum in one penis is incomplete, and there is only a corpus cavernosum and a spongiosum surrounding the functioning urethra in the other penis. Notable clinical cases
Diphallia is usually accompanied by systemic anomalies; their extent varies, ranging from no associated anomaly to multiple anomalies including urogenital, gastrointestinal and musculoskeletal systems. Penile duplication also varies from a single penis with double glans to complete double penises.
The canonical definition of this disorder precludes permanent weakness in the definition of this disorder. In practice, however, this has not been strictly adhered to in the literature. Pathophysiology
Paramyotonia congenita (as well as hyperkalemic periodic paralysis and the potassium-aggravated myotonias) is caused by mutations in a sodium channel, SCN4A. The phenotype of patients with these mutations is indicated in Table 1. These mutations affect fast inactivation of the encoded sodium channel. There are also indications that some mutations lead to altered activation and deactivation. The result of these alterations in channel kinetics is that there is prolonged inward (depolarizing) current following muscle excitation. There is also the introduction of a "window current" due to changes in the voltage sensitivity of the channel’s kinetics. These lead to a general increase in cellular excitability, as shown in figure 1. There has been one study of a large number of patients with paramyotonia congenita. Of 26 kindreds, it found that 17 (71%) had a mutation in SCN4A while 6 (29%) had no known mutation. There is no large difference between these two groups except that patients with no known mutation have attacks precipitated less by cold but more by hunger, are much more likely to have normal muscle biopsies, and show less decreased compound muscle action potentials when compared to patients with known mutations. Diagnosis
Diagnosis of paramyotonia congenita is made upon evaluation of patient symptoms and case history. Myotonia must increase with exercise or movement and usually must worsen in cold temperatures.