AIDS dementia complex complicated by cytomegalovirus encephalopathy

J Neurol (1993) 240 : 223-231

Journal of

Neurology © Springer-Verlag1993

AIDS dementia complex complicated by cytomegalovirus encephalopathy Milan Fiala 1'3, Elyse J. Singer 2, Michael C. Graves 1, Wallace W. Tourtellotte 2, John A. Stewart 4, Charles A. Schable 4, Roy H. Rhodes 5, Harry V. Vinters 6 ~Department of Neurology, UCLA School of Medicine, Reed Building, 710 Westwood Plaza, Los Angeles, CA 90024, USA 2Department of Neurology, Wadsworth Veterans Administration Center, Los Angeles, California, USA 3AIDS Education and Teaching Center, Charles R. Drew University of Medicine and Science, Los Angeles, California, USA 4Viral Exanthems and Herpes Viruses Branch, and Retrovirology Branch, Communicable Disease Center, Atlanta, Georgia, USA 5Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA 6Department of Pathology (Neuropathology) and Brain Research Institute, UCLA School of Medicine, Los Angeles, California, USA Received: 28 April 1992 / Received in revised form: 23 July 1992 / Accepted: 31 July 1992

Abstract. We have studied longitudinally ten patients with AIDS encephalopathy with respect to pathogenetic roles of human immunodeficiency virus (HIV) and cytomegalovirus (CMV). Three patients manifested typical AIDS dementia complex (ADC) (initially without retinitis and with slowly progressive cognitive, motor and behavioral abnormalities which were zidovudine-responsive, and relatively preserved CD4 + T cells), and seven patients presented with AIDS dementia complex complicated by CMV encephalopathy (ACE) (with CMV retinitis, peripheral neuropathy, altered sensorium, and rapidly declining clinical and immunological status). Whereas only HIV antibody was elevated in the spinal fluid of patients with ADC, both virus infections were active in the central nervous system of patients with ACE as shown by HIV p24 antigenemia and antigenrrhachia, elevated HIV and CMV antibody in the spinal fluid, disseminated CMV infection with retinitis, and basilar ventriculoencephalitis with multinucleated cytomegalic cells containing CMV and HIV proteins and CMV DNA. The recognition of A D C and ACE is important, since some patients with ACE may respond to ganciclovir or foscarnet. Key words: Acquired immunodeficiency syndrome (AIDS) - AIDS dementia complex - Human immunodeficiency virus - Cytomegalovirus (CMV) retinitis - CMV encephalopathy

Introduction AIDS dementia complex (ADC) has been described as a syndrome which initially presents with cognitive dysfunction (deficits in memory, attention, and concentration) Correspondence to: M. Fiala, Department of Neurology, UCLA School of Medicine, Reed Building, 710 Westwood Plaza, Los Angeles, CA 90024, USA

and behavioral changes (social isolation and apathy), and progresses to include motor signs (tremor, incoordination, leg weakness, and spasticity) [24]. A D C is attributed to human immunodeficiency virus (HIV) infection of the central nervous system (CNS) [10, 12, 14, 17, 34]. The exact neuropathophysiology of ADC is unclear; HIV infection has been found predominantly in subcortical areas [3, 32] in endothelial cells, monocyte/macrophages, and multinucleated cells [10, 14, 31, 42], with rare infection of astrocytes [31, 33, 42]. Neuronal infection by HIV is rare in vivo, although it has been demonstrated in vitro [18]. Various hypotheses have been proposed to explain the etiology of ADC, including (a) the ability of HIV to enhance release of tumor necrosis factor alpha or other inflammatory cell products by monocyte/macrophage cells [13, 19, 22, 29]; (b) dysfunction of the bloodbrain barrier resulting from HIV infection [30, 31]; (c) cytopathic or metabolic alterations of astrocytes [5, 6, 15, 30, 31]; (d) toxicity of HIV envelope peptide gpl20 for neurons either via direct gp120 neurotoxicity [7] or by interference with binding of the neurotransmitter vasoactive intestinal peptide [27]; (e) autoimmune damage due to crossreacting antibodies against HIV and HIV-like normal CNS determinants [31, 38]; and (f) neurotoxicity due to high cerebrospinal fluid (CSF) levels of quinolinic acid [11], an excitatory neurotoxin. A role for other opportunistic agents, in particular cytomegalovirus (CMV) (which had been documented within the brain since the neurological complications of AIDS were first described [26, 37], has been proposed in some patients [25]. Although neuropathological studies have revealed a spectrum of CMV- and HIV-related pathology [23], and although isolated cases of CMV encephalitis have been noted in living AIDS patients [9, 20], there has been little appreciation of the role of CMV in the later stages of AIDS CNS disease. It is our hypothesis, documented by the evidence presented herein, that patients infected in the CNS by HIV alone display ADC as described by Navia

224 et al. [24] and Price a n d B r e w [28], w h e r e a s a subgroups of patients who are superinfected in the CNS by C M V manifest a s y n d r o m e of A D C c o m p l i c a t e d b y C M V e n c e p h a l o p a t h y ( A C E ) , w h i c h is clinically m o r e f u l m i n a n t t h a n A D C .

Patients and methods We have evaluated 60 patients admitted with AIDS to Eisenhower Medical Center (EMC), Rancho Mirage, California, by neurological and ophthalmological examinations as described previously [9]. When examined on the first or second admission, 24 (40%) of these 60 patients had CMV retinitis. Four (11%) of the 36 patients without retinitis manifested an encephalopathic condition compatible with ADC [28] and 3 were included in this study. Sixteen (67%) of the 24 patients with retinitis succumbed to a more Iulminant encephalopathy with clinical and virological features resembling the condition described herein as ACE, and 7 of these 16 are the subject of this study. The remaining 9 encephalopathic patients also manifested retinitis, altered sensorium and seizures and all had CMV viremia; however, detailed neurological and neuropathological studies could not be, performed. Two patients with ADC were also tested using a standard battery of neuropsychological tests devised for a longitudinal study of ADC at the West Los Angeles Veterans Administration Medical Center. In patients admitted to EMC for the first time with the diagnosis of AIDS, CMV retinitis was recognized in the following proportion (%) of cases. 1985-7/10 (70%); 1986-12/30 (40%); 19875/30 (17%); 1988-3/37 (8%); 1989-6/38 (16%); 1990 (January to August)- 4/23 (17%).

Immunological, viral, and serological studies All patients were HIV antibody positive. Lymphocyte subsets reacting to OKT4+ and OKT8+ antibodies (Coulter, Hialeah, Fla.) were assayed by flow cytometry on the Coulter Epic 5 apparatus. A corrected ratio of CMV antibodies in CSF and serum (CSF/serum antibody ratio) was calculated as a ratio of CSF antibody titer divided by CSF IgG (mg/dl), and of serum antibody titer divided by serum IgG (mg/dl). CMV antibody titers were measured by the CDC enzyme immunoassay (EIA) [40]. In this assay the AD-169 strain of CMV was used to sensitize 96-well microtitration plates. After incubation with serum samples, bound antigenantibody complex was detected with goat antihuman IgG conjugated with alkaline phosphatase and p-nitrophenyl phosphate substrate. Color development was read at 405 nm with the Dynatech MR600 microplate reader. The net absorbance value for each serum sample was determined by subtracting the control well values from the CMV well values. The final EIA value was determined by a calibration procedure using three standard sera on each plate and linear regression analysis. This EIA value is proportional to the amount of CMV antibody in the test serum; increases of 60% or more between any two serum specimens indicate recent CMV infection, reinfection, or reactivation. HIV antibody was assayed by Western blot and EIA (Genetic Systems Corporation, Seattle, Wash.). HIV p24 antigen was assayed by enzyme-linked immunoassy (Abbott Lab, North Chicago, Ill. or Coulter, Hialeah, Fla.). CMV viremia was detected and quantitated in human foreskin fibroblasts, inoculated with 105 or 106 leukocytes, by a microplaque assay as described [8].

Neuropathological study Brain specimens were examined following routine fixation (10-14 days) in neutral buffered formalin. For case 5, only fragments of the brain were available for examination, whereas for case 4, the gross brain specimen was available for evaluation. Routine tissue blocks v~ere embedded in paraffin and histological sections made using standard techniques [39].

Immune staining for CMV antigen was done by an immunoperoxidase technique using the mouse monoclonal antibody MABS10 (1:500; Chemicon, Temecula, Calif.) against CMV immediate early antigen of 72kDa, and avidin-biotin-peroxidase complex (Vectastain Elite ABC Kit; Vector Laboratories, Burlingame, Calif.) activated by 3,3'-diaminobenzidine (DAB) and H202, as described previously [30], Immune staining for HIV employed this technique with monoclonal anti-gp41 (1:750; Genetic Systems, Redmond, Wash.). In situ hybridization for CMV was performed on 8-gm paraffin sections mounted on poly-L-lysine-coated glass slides after drying in a 60°C oven for 60 min, removal of paraffin and incubation in 3% H202 in phosphate buffered saline (PBS) for 4min. Rinsed sections were digested for 60 min at 37°C with proteinase K (10 gg/ ml) in PBS, washed with PBS-EDTA (Pathogene Kit; Enzo Diagnostics, New York) and air dried. Biotinylated DNA prob6 reagent for CMV (Pathogene Kit) was applied to each section, a coverglass was placed, and the slides were heated at 92°C for 10 rain. Hybridization was then allowed to proceed at room temperature for 20 min and the coverglass was removed. The sections were covered with post-hybridization reagent (Pathogene Kit) for 10min, rinsed with PBS, incubated with ABC from the Elite Kit for 20 min, rinsed, incubated with DAB-H202 substrate for 20 min, rinsed, counterstained briefly with hematoxylin, dehydrated, and mounted with Permount.

Results

Clinical observations P a t i e n t s with A D C (case 1 - 3 ) h a d a m i l d e r a n d m o r e slowly p r o g r e s s i v e c o u r s e w h e n c o m p a r e d with t h o s e with A C E (case 4 - 1 0 ) , a n d seizures, c o m a , retinitis, C M V v i r e m i a a n d virus infection of C S F w e r e e n c o u n t e r e d o n l y a m o n g A C E cases, as s e e n in t h e following case h i s t o r i e s ( T a b l e 1).

ADCcases Case 1. A 5 4 - y e a r - o l d b i s e x u a l m a l e p o d i a t r i s t n o t e d g r a d u a l o n s e t o f m e m o r y loss, s t u m b l i n g , a n d a l t e r e d h a n d w r i t i n g in M a r c h 1987. I n A u g u s t 1987, he was adm i t t e d to E M C with d i s o r i e n t a t i o n a n d d e h y d r a t i o n a n d his C D 4 + c o u n t was 0.158 × 109/1. N e u r o l o g i c a l e x a m i n a t i o n was r e m a r k a b l e for slow s a c c a d e s , t h e i n t r u s i o n of s a c c a d e s o n t o s m o o t h p u r s u i t s a n d m i l d facial h y p o m o t i l i t y . N e u r o p s y c h o l o g i c a l testing r e v e a l e d t h a t his p e r f o r m a n c e was m o r e t h a n two s t a n d a r d d e v i a t i o n s below t h e m e a n o n a s t a n d a r d i z e d test b a t t e r y . Z i d o v u d i n e was a d m i n i s t e r e d at 1200 m g / d a y a n d has b e e n c o n t i n u e d until t h e p r e s e n t t i m e . D i d e o x y i n o s i n e was a d d e d at 54 m o n t h s . Sixty m o n t h s a f t e r t h e diagnosis, t h e p a t i e n t is alive a n d t r a v e l l i n g i n d e p e n d e n t l y . Case 2. A 3 1 - y e a r - o l d h o m o s e x u a l m a l e p r o p e r t y m a n a g e r e x p e r i e n c e d t h e o n s e t of l o w - g r a d e fever, l y m p h a d e n o p a t h y , d i a r r h e a , d e p r e s s i o n , a n d anxiety. I n N o v e m b e r 1987, h e r e p o r t e d m e m o r y loss, difficulty with c a l c u l a t i o n s a n d w o r d - f i n d i n g , left leg w e a k n e s s , a n d int e r m i t t e n t p a r e s t h e s i a s in all e x t r e m i t i e s . N e u r o l o g i c a l e x a m i n a t i o n d e m o n s t r a t e d p o o r r e c e n t m e m o r y , gait ataxia, tremor, generalized hyporeflexia, hypoesthesia a n d w e a k n e s s in t h e left leg. A n e u r o p s y c h o l o g i c a l test b a t t e r y s h o w e d his p e r f o r m a n c e to b e at a level two start-

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