Mohammed T. Abou-Saleh

CJD AND OTHER DEGENERATIVE CAUSES OF DEMENTIA 279absent, the patient presenting with a triad of symptomscomprising dementia, gait dyspraxia and urinary incontinence.Cerebral atrophy is seen on CT scan, but the condition may besuspected when the ventricles are disproportionately large incomparison with the degree of sulcal widening. Unfortunatelythere is no reliable diagnostic test, as evidenced by recent reportsin the literature 29 . Some claims have been made for isotopecisternography, which shows delayed passage of radioactivityfrom the ventricles to the area surrounding the cerebralconvexities. Treatment is by the insertion of a CSF shunt, andin some cases this has even been used as the definitive diagnostictest. No cause has been found to account for the condition,although in some cases a ‘‘secondary’’ form is recognized as beingdue to previous meningeal inflammation or head injury andsubsequent impairment of CSF uptake.POST-TRAUMATIC DEMENTIADementia pugilistica in boxers presents as a progressive neurologicaldisease with involvement of pyramidal, extrapyramidaland cerebellar systems, in addition to memory loss and personalitychange. The onset may be many years after the cessation of aboxing career. The pathological appearances resemble those ofAlzheimer’s disease, but neurofibrillary tangles predominate, withan absence of plaques 30 .HUNTINGTON’S DISEASEThis autosomal dominant inherited condition, with an onsetusually after the age of 30 and rarely after the age of 70, haschoreiform movements and dementia as its most commonpresenting features. Diagnosis can now be confirmed by analysingthe huntingtin gene on chromosome 5 for CAG triplet repeats inexcess of 35. Atrophy of the caudate nucleus may be seen intypical cases on CT or MRI scan. The dementia does differ fromthat of Alzheimer’s disease by virtue of the fact that there is moredifficulty with tests of letter fluency and the copying of geometricfeatures 31 , indicating that the dementia is of the subcortical type.FAMILIAL SPASTIC PARAPARESIS, ORSPINOCEREBELLAR ATROPHY ASSOCIATEDWITH DEMENTIAThese conditions are considered together as both may produce adementing-type illness which is in itself indistinguishable fromother forms of dementia, but is set apart by the presence of othersigns, such as a spastic paraparesis or a cerebellar syndrome. Inboth, the dementia advances only slowly, and may only be aminor feature of the illness, although recent work has shown thatthe cognitive impairment may be subclinical in some kindreds andoverlooked with routine clinical screening tests 32 .PROGRESSIVE SUBCORTICAL GLIOSISThis condition, described in 1967, presents as a dementing processwith subcortical features and may mimic Alzheimer’s disease.Infrequent findings are signs of extrapyramidal involvement, andcases with supranuclear gaze palsy have been described 33 . Theclinical course extends over years, often with a final akinetic mutestage. The cardinal pathological feature is intense gliosis andastrocytic hyperplasia affecting the subcortical structures of thethalamus, basal ganglia, brainstem grey matter and ventral hornsof the spinal cord.CORTICO-BASAL DEGENERATIONThe more prominent signs of extrapyramidal dystonias, corticalsensory loss, dyspraxia, myoclonus (often focal) and the ‘‘alienhand’’ sign, tend to obscure a slowly developing dementia which isusually cortical in nature. The presence of ideomotor dyspraxiamay help to distinguish this extrapyramidal syndrome fromdisorders such as PSP 34 . The mean age of onset in a series of 15patients was 60 years 35 . No investigation is diagnostic, andconfirmation of the diagnosis is by finding nerve cell loss andgliosis in the frontoparietal cortex and extrapyramidal system.DEMENTIA LACKING SPECIFIC HISTOLOGICALFEATURESAs well as being without specific histology, the pattern ofdementia is unremarkable, being of a frontal lobe type moreclosely resembling Pick’s disease, with many cases also showingextrapyramidal features. The pathological features are corticalvacuolation and astrocytosis in the deeper layers, withoutneurofibrillary tangles, plaques or Pick or Lewy bodies.REFERENCES1. Creutzfeldt HG. Uber eine eigenartige herdformige Ekrankung desZentralnervensystems. Z Ces Neurol Psychiat 1920; 57: 1–18.2. Jakob A. Uber eigenartige Erkrankungen des Zentralnervensystemsmit bemerkenswertem anatomischen Befunde (spastichePseudosclerose-Encephalomyelopathie mit disseminiertenDegenerationsherden). Z Ces Neurol Psychiat 1921; 64: 147.3. Gajdusek DC, Gibbs CJ Jr, Alpers M. 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