Comment-Patients with normal and abnor¬ mal EEGs were similar in age, sex, and immuni¬ zation history at the time of onset of symptoms. The severity of their disease did not vary, nor did the level of measles antibody or the length of survival. One patient had well-developed myoclonus at the time his EEG was normal. One pa¬ tient in each group was admitted with chorioretinitis and three are still living one to seven years after onset of the disease. The significance of measles immunization in these patients is uncertain. Since six of them also had an antecedent history of natural measles, this may not have been the primary an¬ tigenic exposure. There is nothing unusual about the clinical course or EEGs in the patients re¬ ported to date who have been given vaccine.3 We are aware of only two reports of SSPE in which the initial EEG was normal and two of the three cases converted to a periodic pattern.*s We have no satisfactory explanation for this unex¬ pectedly high incidence of normal EEGs at a time when clinical disease was moderately advanced. It is not because the cases were recognized early. When the EEGs were obtained, most of the patients had prominent personality changes and school problems and, on the average, had been symptomatic for six months. It is not surprising that the EEG in SSPE should vary markedly in different patients and

during the course of disease, since the pathologic process is variable, involving gray and white matter at all levels of the neuraxis. Presumably the patients with normal EEGs have primary subcortical disease, but even this is uncertain.

Elevated Serum Creatine Phosphokinase Levels in

tivities. The results are summarized in the Table. The girls were active in sports (basketball and gym), but none of their values fell outside the normal range for our laboratory (0 to 108 international units [IU]). (Details of methodology available on request.) Their mean value (59 IU) was comparable to a larger multi-aged control group. Seventeen of the 28 values obtained in boys were elevated, and two boys had consistently elevated determinations. Although no quantitative measurement of exercise was made, it was not possible to relate CPK values to the gross level of

Healthy Teen-aged Boys During

study carried out at the Montreal Children's Hospital involving measurement of serum creatine phosphokinase (CPK) levels in healthy children, it was found that some teenaged boys had elevated values. We then studied a group of teen-aged children at least five times over a seven-week period to estimate the normal intrapatient and interpatient variation in CPK levels. There was no restriction of sporting aca

Serial CPK Values Obtained in Sex

M M

M§ M§ M

Age, 15 15 15 15 15 16 15 15 13 15 14

yr

59 89 82 83 69

41 43 63 102 59

88t 911 584t 257t

106f 82t 272t 101t

55 67

72 74

As the disease advances and brain function is progressively compromised, the myoclonic activ¬ ity becomes less and the periodic complexes on EEGs often disappear.2 At this time, the EEG usually shows excessive background slowing and often is asymmetrical, indicating structural brain disease. The inflammatory reaction in ad¬ vanced disease is minimal; the brain shows ex¬ cessive gliosis and virus is difficult to detect in the lesions and rarely can be rescued from the tissues in the laboratory. The recognition that EEGs can be normal when SSPE is moderately advanced is a stimulus to obtain CSF measles antibody titers when this condition is suspected clinically. The EEG nor¬ mality in no way indicates a better prognosis for these patients, only possible subcortical local¬ ization of their primary abnormality, which in time will progress to produce an obviously abnor¬ mal tracing. Sttmmcm/.-Six of 11 patients with moderately advanced SSPE had normal EEGs when first evaluated. The EEGs in five subsequently re¬ verted to a classical periodic pattern. These pa¬ tients could not be distinguished clinically from

Teen-aged School Children* CPK Values, IU 40 38 45 51 60 57 63 55 60 55

79f

63f

36 53 82 58 43

91t

306

128

263t 150t

2911 275t

247t 155t

75 120

86 109

236

63

Normal overall range: 0 to 108 IU; range for girls: 36 to 102 IU; range for boys: 55 to 584 IU; mean for boys: 191 IU. *

t Played hockey on day prior to test. t Had intramuscular injection on day prior to test. § Brothers.

191t mean

those with abnormal EEGs, nor were there sub¬ stantial differences in the laboratory values. When SSPE is suspected clinically, CSF antimeasles antibodies should be determined even when the EEG is normal. This investigation was supported in part by a Special from the National Traineeship Award (5F11-NSO2620) Institute of Neurological Disease and Stroke (Dr. Sisk). Dr. Griffith is an Investigator of the Howard Hughes

Medical Institute.

Michael A. Sisk, MD John F. Griffith, MD Dept of Pediatrics Duke Univ Med Center Durham, NC 27710 1. Fenyo E, Hasznos T: Periodic EEG complexes in subacute panencephalitis. Electroencephalogr Clin Neurophysiol 16:446-458, 1964. 2. Cobb W: The periodic events of subacute sclerosing panencephalitis. Electroencephalogr Clin Neurophysiol 21:278-294, 1966. 3. Jabbour JT, Duenas DA, Sever JL, et al: Epidemiology of subacute sclerosing panencephalitis. JAMA 220:959-962, 1972.

4. Freeman JM: The clinical spectrum and

early diagnosis of Dawson's encephalitis. J Pediatr 75:590-603, 1969. 5. Ibrahim MM, Jeavons PM: The value of electroencephalography in the diagnosis of SSPE. Dev Med Child Neurol 16:295-307, 1974.

sporting activity on the day prior to the morning test (see Table) or to any evidence of trauma. Markedly abnormal values were obtained in the

absence of sports, and normal values were ob¬ tained even after vigorous activity. Although elevated CPK levels may occur in a number of circumstances,' and sporadically in normal persons,2 they seem to be almost characteristic of teen-aged boys. This may reflect a muscle that is susceptible to the release of CPK because of a high level of growth and activity. That the two boys with consistently elevated levels were brothers may reflect a genetic component, or simply the fact that they were the most muscu¬ lar of the group. Griffiths commented on the pos¬ sible lability of CPK levels in children.3 These findings caution against attaching too much im¬ portance to the isolated finding of an elevated CPK in a teen-aged boy. A. Hunter, MD Health Sciences Children's Center Genetics Dept Winnipeg, Manitoba R3E OW1 Canada

108Î 338t 120

for girls: 59 IU;

1. Kyei-Mensah K, Tyrrell JH, Sumner DW: Clinical and genetic aspects of malignant hyperpyrexia. Proc R Soc Med 66:63-66, 1973. 2. Perry TB, Fraser FC: Variability of serum creatine phosphokinase activity in normal women and carriers of the gene for Duchenne muscular dystrophy. Neurology 23:1316-1323, 1973. 3. Griffiths PD: Serum levels of ATP: Creatine phosphotransferase (creatine kinase): The normal range and effect of muscular activity. Clin Chim Acta 13:413-420, 1966.

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