You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
oral contraceptive pills ( ocps ) are commonly used for contraception , polycystic ovarian syndrome , amenorrhea , menorrhagia , dysmenorrhea , endometriosis , etc .
, common side effects of ocps include nausea , vomiting , headache , bloating , breast tenderness , swelling of the feet , weight gain , breakthrough bleeding , and venous thromboembolism .
neurological adverse effects associated with ocps are migraine , depression , psychosis , and cerebral infarction .
chorea caused by ocps is extremely rare and only very few cases are reported in the literature .
the onset of chorea usually varies from few weeks to several years after starting therapy . here
, we report a case of chorea developing within 1 week of initiating ocps in an adolescent girl with polycystic ovarian disease .
a 17-year - old non - obese , unmarried girl presented to our hospital with irregular cycles and hirsutism for 2 years duration .
investigations revealed raised lh : fsh ratio ( 3:1 ) and a slightly raised serum testosterone level .
she was diagnosed to have polycystic ovarian disease and was prescribed ocps for treatment of irregular cycles .
the ocps contained a combination of ethinyl estradiol 0.035 mg and cyproterone acetate 2 mg , which was prescribed once daily for 21 days .
the patient presented with complaints of abnormal movements of right extremities within 1 week of starting therapy .
there was no previous history suggestive of streptococcal infection , rheumatic fever or drug therapy . on examination ,
investigations revealed normal blood counts , erythrocyte sedimentation rate , serum electrolytes , renal , liver , and thyroid function tests .
she was diagnosed to have ocps induced hemichorea after ruling out other common causes of chorea .
neurological side effects of ocps have been linked to alterations in coagulation pathways and secondary vascular complications .
chorea is an abnormal involuntary movement disorder characterized by brief , semi - directed , irregular movements that are not repetitive or rhythmic , but appear to flow from one muscle to the next .
the first description of chorea associated with ocps was reported by fernando in 1966 and subsequently few similar published reports established ocps as a cause of chorea .
no particular oral contraceptive preparation was consistently associated with chorea , and both low and high - dose preparations can cause this movement disorder .
it has been well - established that estrogens have a definite but complex modulatory action in dopaminergic systems .
hence , the estrogenic component of ocps is most likely the causative factor in the chorea induced by these agents . some cases of ocps induced chorea are caused by reactivation of sydenham 's chorea seen in rheumatic fever . however , ocps induced chorea have no clear relationship with sydenham 's chorea , or streptococcal infection have also been reported , similar to our case .
the onset of chorea varies widely from few weeks to several years ( average duration : 9 weeks ) .
the shortest time interval between ocp intake and development of chorea reported in the literature is eight weeks in the patient with no significant medical history . in most cases , symptoms subside promptly after withdrawing the offending drug , usually within a period of 23 months . in this index case ,
causality assessment by naranjo adverse drug reaction probability scale got a score of 6 , suggesting a  probable  relationship between the reaction and the drug .
prior knowledge of this rare adverse effect and high index of suspicion can help in early diagnosis and discontinuation of therapy .
chorea is a neurological adverse effect of oral contraceptive pills ( ocps ) . 
 the onset of chorea following ocps usage varies widely from few weeks to several years . 
 we report a rare case of chorea which developed within a week of starting ocps in an adolescent girl with polycystic ovarian disease .