The use of prostaglandin E1 is contraindicated in patients with predisposition to priapism (e.g., those with sickle cell anemia), anatomical deformity of the penis, or penile implants. Phentolamine (2 mg) is often added. Visual and tactile stimulation produces better results. Some authors recommend the use of sildenafil by mouth to replace the injectable drugs in cases of contraindications, although the efficacy of such medication is controversial.Before the injection of the chosen drug, the flow pattern is monophasic, with low systolic velocities and an absence of diastolic flow. After injection, systolic and diastolic peak velocities should increase, decreasing progressively with vein occlusion and becoming negative when the penis becomes rigid (see image below). The reference values vary across studies, ranging from > 25 cm/s to > 35 cm/s. Values above 35 cm/s indicate the absence of arterial disease, values below 25 cm/s indicate arterial insufficiency, and values of 25–35 cm/s are indeterminate because they are less specific (see image below). The data obtained should be correlated with the degree of erection observed. If the peak systolic velocities are normal, the final diastolic velocities should be evaluated, those above 5 cm/s being associated with venogenic ED. Other workup methods
Penile nerves function
Tests such as the bulbocavernosus reflex test are used to ascertain whether there is enough nerve sensation in the penis. The physician squeezes the glans (head) of the penis, which immediately causes the anus to contract if nerve function is normal.
A parapharyngeal abscess is a deep neck space abscess of the parapharyngeal space (or pharyngomaxillary space), which is lateral to the superior pharyngeal constrictor muscle and medial to the masseter muscle. This space is divided by the styloid process into anterior and posterior compartments. The posterior compartment contains the carotid artery, internal jugular vein, and many nerves. Signs and symptoms
Symptoms include fever, sore throat, painful swallowing, and swelling in the neck. An anterior space abscess can cause lockjaw (spasm of jaw muscle), and hard mass formation along the angle of the mandible, with medial bulging of the tonsil and lateral pharyngeal wall. A posterior space abscess causes swelling in the posterior pharyngeal wall, and lockjaw is minimal. Other structures within the carotid sheath may be involved, causing rigors, high fever, bacteremia, neurologic deficit, or a massive haemorrhage caused by carotid artery rupture. Cause
Infection can occur from:

Pharynx: acute and chronic infection of tonsil and adenoids
Teeth: dental infection occurs from lower last molar tooth
Ear: Bezolds abscess and petrositis
Other space: infection of parotid retropharyngeal space
External trauma: penetrating injuries of neck, injection of local anaesthetic

Epidemiology
Parapharyngeal abscess is more common in male than the female gender. Any age group can develop a parapharyngeal abscess but it is most commonly seen in children and adolescents. Adults who are immunocompromised are also at high risk. == References ==