1053 HIV SEROPREVALENCE AMONG PROSTITUTES she had visual field defects and radiological studies (CT and cistemography) revealed sagging of the chi...

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she had visual field defects and

radiological studies (CT


cistemography) revealed sagging of the chiasm into the sella. The chiasm was explored and the sella was plugged with muscle. There was some chiasmal arachnoiditis. Visual fields improved and there

significant relation between non-intravenous use of cocaine and crack and seropositivity (table). In a log-linear analysis of different models of causality (eg, type of prostitution, use of condoms, drug use patterns, and seroprevalence) the only significant relation was between any drug use and rates of HIV infection. The full analysis will be published elsewhere. The striking finding is that non-intravenous drug use (cocaine and crack) is associated with at least as high levels of seropositivity as intravenous drug use. These fmdings, and other observations, indicate that it is the number of sexual encounters that places female (and male) crack users at risk. Typically, female users trade sexual favours for crack, and during one night they may have sex with many partners. Although my survey was in prostitutes, the implication is that many women who use crack but who would not define themselves as prostitutes may also be at increased risk of HIV infection. Current prevention efforts have been concentrated on intravenous drug users and on prostitutes as potential risk groups, so female cocaine users who do not see themselves as belonging to one of these groups may be less likely than intravenous drug users to develop strategies to protect themselves and to modify their behaviour. Drugs may affect the immune system directly--eg, in laboratory animals cocaine may weaken the immune system.’1 HIV prevention efforts should concentrate not only on intravenous drug users but also on cocaine/crack users, and health authorities must correct the impression that among drug users it is only those who share needles who are at risk of HIV infection. I thank Dr Charles Denk and Dr William Komblum of the CUNY Graduate School for their help. Center for Social Research, CUNY Graduate School, New York, NY 10036, USA, and Narcotic and Drug Research, Inc, New York City

has been no further visual deterioration. The cause of the long-term increase in intracranial pressure has not been determined. A case of pituitary apoplexy similar to that of Montalban et al has been followed up for 40 years. A radiologist had acute headache at the age of 41 in 1942, diagnosed as subarachnoid haemorrhage at a local hospital. A week later he vomited and became blind. Surgical exploration of the pituitary was proposed as the plain X-ray had shown a grossly enlarged sella on the tenth day after the headache. However, that day vision began to recover and rapidly returned to normal without any treatment. He complained to me at the age of 80 of visual difficulties which proved to be refractive problems. His vision was normal with no field defect, as were his general examination and endocrine screening tests. X-rays of the sella gave an anterio-posterior diameter of 24 mm and CT scanning revealed an empty sella. Montalban et al also refer to ESS in patients with functioning pituitary adenomas mistakenly reporting this as "pituitary aneurysm".2 Two such cases have been seen recently with a radiological ESS (hypersecretion of prolactin in one case and of ACTH in the other). Such cases are extremely rare. Pituitary aneurysms are also very rare, and used to pose a lethal trap when pituitary surgery was done in the past without preceding angiography. In this context I mention two recent cases with a radiological ESS, one of whom had an unruptured internal carotid aneurysm and the other an unruptured middle cerebral artery aneurysm. Are these coincidences? Clinical Neurosciences Department, Western General Hospital, Edinburgh EH4 2XU 1. 2

E. H.


Foley KM, Posmer JB. Does pseudotumour cerebri cause the empty sella syndrome? Neurology 1975; 25: 565-69 Bjerre P, Lindholm J, Videbaek H The spontaneous course of pituitary adenomas and occurrence of an empty sella in untreated acromegaly J Clin Endocrinol Metab 1986, 63: 287-91


SIR,-Dr Mauch and colleagues (April 9, p 521) present results substantiating the value of nuclear magnetic resonance imaging in the diagnosis of multiple sclerosis in patients with myelitis. Caution is, however, required in interpreting the apparently higher rate of positive brain scans than in other series,’ especially as only 10 of their 18 patients had other evidence of multiple sclerosis. Multiple foci of high signal intensity on T2-weighted spin-echo images are common findings in elderly patients.2,3The incidence in the normal population over the age of 60 years is about 25 %.’Many pathological processes have been suggested to account for this finding, the most convincing being small vessel disease. In addition, even in patients with a clinical picture consistent with multiple sclerosis, conditions such as acute disseminated encephalomyelitis, sarcoidosis, and vasculitis can cause identical appearances on T2-weighted images. Unfortunately multiple lesions in the cerebral white matter cannot be regarded as diagnostic of multiple sclerosis, particularly in patients aged above 50. The technique is highly sensitive, but, with current knowledge, non-specific. further

I Van Dyke C, 1387-90.


al. Cocaine


natural killer cell activity

J Clin Invest 1986, 77:


SIR,-Dr Montalban and colleagues (April 2, p 774) report three patients with apoplexy affecting pituitary tumour at presentation who were treated medically and progressed to hypopituitarism with the radiological appearances of an empty sella at follow-up over six to eighteen months. I would add that an empty sella is often an insignificant finding when computerised tomography (CT) of the head is done in patients who do not have pituitary or parapituitary symptoms, and in whom the sella looks normal on plain X-rays. Pathological significance should be given to the CT finding of an empty sella together with plain X-ray changes of the sella suggesting either erosion of clinoids from raised intracranial pressure or enlargement of the sella by an intrasellar tumour. Montalban and colleagues refer to this development of the empty sella syndrome (ESS) as a consequence of raised intracranial pressure. One such case has been followed up in this department for a long time. At the age of 51 a woman was found to have papilloedema when she complained of deteriorating vision in 1971. Air encephalography and angiography were normal and she improved on symptomatic treatment with dexamethasone. In 1976, when her condition worsened, an air encephalogram showed an empty sella. She was treated with prednisolone. In 1978 her visual acuity dropped. She now had optic atrophy and her cerebrospinal pressure was 290 mm H20. In 1980, despite more corticosteroid therapy, after which cerebrospinal fluid pressure became normal,

Lysholm Radiological Department, National Hospital, London WC1N 3BG


WI, Blumhardt LD, et al Magnetic resonance imaging in isolated noncompressive spinal cord syndromes. Ann Neurol 1987, 22: 714-23. 2. Zimmerman RD, Fleming CA, Lee BCP, et al. Periventricular hyperintensity as seen by magnetic resonance: Prevalence and signficance AJNR 1986; 7: 13-20. 3 Awad IA, Spetzler RF, Hodak JA, et al. Incidental subcortical lesions identified on MRI in the elderly I- Correlation with age and cerebrovascular risk factors Stroke 1986; 17: 1084-89, 4. Bradley WG, Waluck V, Brandt-Zawadski M, et al. Patchy, periventricular white matter lesions in the elderly a common observation during NMR imaging. Noninvasive, Med Imag 1984; 1: 35-41. 1. Miller DH, McDonald