Recurrent painful ophthalmoplegic neuropathy (RPON), previously known as ophthalmoplegic migraine (OM), is a rare neurological disorder that is characterized by repeated headache attacks and reversible ipsilateral paresis of one or more ocular cranial nerves (CN). Oculomotor nerve (CNIII) is by far the most common cranial nerve involves in RPON, while abducens nerve (CNVI) and trochlear nerve (CNIV) involvements are also reported. Globally, RPON was estimated to have an annual incidence rate of 0.7 per million as of 1990, no further epidemiological studies have been conducted. It occurs more often in children and females.Although the etiology of RPON is unknown owing to the rarity of this disease, various potential theories including migrainous and neuropathic mechanisms have been developed. Diagnosis is based on physical examination, magnetic resonance imaging (MRI), and ruling out other possible causes. Despite the fact that there are currently no evidence-based treatment guidelines for RPON, the most commonly used medications are corticosteroids that have been proven effective in alleviating the symptoms. As for people who are unresponsive to steroids, other treatments, such as anti-migraine drugs, botulinum toxin injection and strabismus surgery, may be utilized. For prevention, several medications including calcium channel blockers may be used. However, none have been proved consistently effective. RPON has a good overall prognosis as a result of the self-limiting nature of the condition, but permanent neurological damage may accumulate over repeated episodes. Signs and symptoms
The typical symptoms of RPON are recurrent headaches and ipsilateral paralysis of the extraocular muscles (ophthalmoplegia) that are responsible for controlling eye movements.
During the formative phase, X-ray images typically reveal calcium deposits with uniform density and a clear margin. In the more painful resorptive phase, deposits instead appear cloudy and with unclear margins. By arthroscopy, formative stage deposits appear crystalline and chalk-like, while resorptive stage deposits appear smooth resembling toothpaste. Ultrasound is also used to locate and assess calcium deposits. In the formative stage, deposits are hyperechoic and arc-shaped; in the resorptive stage deposits are less echogenic and appear fragmented. Treatment
The first line of treatment for calcific tendinitis is typically nonsteroidal anti-inflammatory drugs to relieve pain, rest for the affected joint, and sometimes physical therapy to avoid joint stiffness. For those with severe pain direct injections of steroids to the affected site are often effective for pain relief, but may interfere with reabsorption of the calcium deposit. For those whose pain doesnt improve with medication and rest, the deposit can be dissolved and removed with techniques called "ultrasound-guided needling", "barbotage", and "US-PICT" (for "ultrasound percutaneous injection in calcific tenditis"). In each, ultrasound is used to locate the deposit and guide a needle to the affected site. There saline and lidocaine are injected to dissolve the deposit, then removed to wash it away. Another common treatment is extracorporeal shockwave therapy, where pulses of sound are used to break up the deposit and promote healing. There is little standardization of energy levels, duration, and time interval of treatment; though most studies report positive outcomes with low- to medium-energy waves (below 0.28 mJ/mm2).