This Month in The Archives of Neurology

Thomas H. Glick, MD, reappraises the value and utility of the sleep-deprived electroencephalogram (EEG). He has surveyed the knowledge and practice of nonneurologists in a community teaching hospital, local and national neurologists and epileptologists, and EEG laboratory protocols, as well as textbook accounts and recommendations related to the value of the sleep-deprived EEG. This review offers insights and recommendations for the clinical use of the sleep and sleep-deprived EEG with a new perspective.

Gogtay et al describe recent advances in magnetic resonance imaging for measuring brain development in healthy, hyperactive, and psychotic children. Specific and characteristic developmental defects are described in the brains of children with attention-deficit/hyperactivity disorder and in child-onset schizophrenia. Advances in magnetic brain imaging thus have the potential to supplement preclinical and postmortem data on normal and abnormal brain development.

Diederich et al have determined whether there is progressive, longitudinal deterioration of color discrimination and contrast sensitivity in patients with Parkinson disease. Of great interest, they found deterioration of both color discrimination and contrast sensitivity, and that both deficits correlated with age; the chromatic deficit additionally correlated with greater impairment of motor functions. These observations expand considerably our understanding of visual deficits in Parkinson disease.

Editorial perspective is provided by Ivan Bodis-Wollner, MD, DSc.

Luchsinger et al have examined the association between caloric intake and the occurrence of Alzheimer disease (AD). In a thorough and precise study, they found that a higher intake of calories and fats may be associated with a higher risk of AD in individuals carrying the APOE ϵ4 allele. These findings support the theory that caloric restriction modifies age-related conditions in humans and suggests caloric restriction and low-fat diets in individuals carrying APOE ϵ4.

Buerger et al have studied to what extent cerebrospinal fluid (CSF) levels of phosphorylated tau protein at threonine 231 (p-tau₂₃₁) distinguish Alzheimer disease (AD) from control subjects and from patients with other dementias. They find that mean CSF levels of p-tau₂₃₁ are significantly elevated in patients with AD compared with all other groups. p-tau₂₃₁ discriminated with a sensitivity of 90.2% at a specificity of 80% between subjects with AD and those without AD. This study shows that increased CSF levels of p-tau₂₃₁ may be a useful, clinically applicable biological marker for the differential diagnosis of AD, particularly for distinguishing AD from frontotemporal dementia.

Louis et al have compared body mass index (calculated as weight in kilograms divided by the square of height in meters) in patients with essential tremor with controls and found, in general, that body mass index was lower in patients with essential tremor than in controls. It is of interest that these data support the view that lower body mass index may be due to increased energy expenditure in patients with essential tremor.

Muellbacher et al describe deafferentation produced by a new technique of regional anesthesia of the upper arm during hand motor practice, which dramatically improved hand motor function, including some activities of daily living, in patients recovering from stroke. The improvement was associated with an increase of transcranial magnetic stimulation–evoked motor output to the practice hand muscles. This is a novel therapeutic strategy that improves hand function in patients with chronic weakness after stroke and may develop into a practical new clinical therapy.figure 1

Grewal and colleagues have described their experience with spinocerebellar ataxia (SCA) type 10 caused by a large expansion of an unstable ATTCT pentanucleotide DNA repeat. Ataxia was the initial symptom in 21 of 22 patients studied, and seizure disorders developed in 11. Although anticipation was apparent in both families, only family 1 showed a strong inverse correlation between age of onset and pentanucleotide repeat expansion. Thus, seizures represent an integral part of the SCA10 phenotype, but family-dependent factors may alter the frequency of the seizures' phenotype and the pattern of intergenerational DNA repeat size expansion. Here is an interesting example of a unique and complex genotype-phenotype correlation study.

Brkanac et al have mapped the gene for a new autosomal dominant spinocerebellar ataxia to chromosome 19q13.4-qter in a single family. This is a 4-generation American family of Dutch and English ethnicity with a "pure" cerebellar ataxia.

Theodosopoulos et al describe their extensive experience in patients who underwent posterior exploration in the treatment of idiopathic trigeminal neuralgia. Postoperatively, trigeminal pain had lessened in 98% and completely resolved in 88% of patients. This is an extensive and comprehensive clinical survey demonstrating the effectiveness of posterior fossa exploration as therapy for idiopathic trigeminal neuralgia.

Brickman and colleagues have determined the longitudinal course of dependence in patients with Alzheimer disease (AD). They demonstrate the validity of their Dependence Scale and that dependency in AD significantly declines with time, independent of global cognition of other self-care deficits. Their scale may indeed be of value for outcomes research, efficacy trials, and behavioral research in AD.