2. Boyd WD, Graham-White J. Blackwood G, et al: Clinical effects of choline in Alzheimer senile dementia. Lancet 2:7 11, 1977 3. Iversen SD: Temporal lobe amnesia, in Whirry CWM, Zangwill OL (eds): Amnesia. Iondon. Butterworth, 1977, pp 136-182 4. Mishkin M: Memory in monkeys severely impaired by com-
bined but not by separate removal of amygdah and hippocampus. Science 273:297-298, 1978 5 . Penfield W, Mathieson G: Memory. Arch Neurol3 1: 145-154, 1974
6. Smith CM, Swash M: Possible biochemical bask of memory
disorder in Alzheimer disease (hypothesis). Ann Neurol 3:471-473, 1978
House Dogs and Multiple Sclerosis Luis Garcia-Buiiuel, MD The paper by Dr Stuart Cook and his associates (Further evidence of a possible association between house dogs and multiple sclerosis. Ann Neurol 3:141-143, 1978), postulating a relationship between ownership of indoor dogs and multiple sclerosis, reports an unusually high incidence of neurological illness among dogs owned by both patients with multiple sclerosis (18%) and controls (1 1%). In a survey of our outpatients, none of 17 patients with multiple sclerosis had owned a dog with signs of neurological disorder, and of 65 individuals with other problems, only 1 (1.5%) could recall ever having a dog so afflicted. The high incidence of neurological illness among the dogs from the control group in the study by Cook e t al suggests the possibility that these dogs, as well as those from the multiple sclerosis group, had increased exposure to some environmental factor. Because the controls were selected from households in the same neighborhoods as their multiple sclerosis counterparts, the implication might be that these areas represented clusters of increased exposure for both the dogs and their owners and that shared exposure to a similar agent occurred, rather than transmission from dog to human.
Postirradiation Myelopathy in Children -
Larry E. Kun,
MD
The suggestion of Sundaresan et al (Radiation myelopathy in children, Ann Neurol 447-50, 1978) that children demonstrate low spinal cord tolerance to irradiation may be seriously questioned. O n e must cautiously analyze developments following radiotherapy with regard to the specific details of treatment. All 3 patients presented by Dr Sundaresan were treated with craniospinal irradiation, o n e of the most complex treatment techniques in the radiotherapeutic armamentarium. Usually such patients are treated with at least three fields: two opposed lateral fields encompassing the cranium and upper cervical cord in continuity and a single posterior field that includes the lower cervical through sacral spinal canal. The technique requires immobilization in the prone position and daily reproducibility of treatment fields; furthermore, the joining of the two lateral fields with the posterior field may invite potential “overlap” or “skip” volumes due to the dosimetry involved. Careful review of the details of treatment for the reported patients is imperative before one assumes that the doses listed in the radiation therapy summary accurately reflect the doses delivered in specific areas of the spinal cord. Indeed, the level of myelopathy reported in the first 2 patients strongly suggests potential overlap or junctional overdosage in the midcervical spine where the lateral fields adjoin the posterior spinal field. The third patient, who had overt central nervous system leukemia, signs of methotrexate encephalopathy, and fungal meningitis at autopsy, showed so many variables that any conclusion as to the cause of her neurological signs is only speculative. Postirradiation myelopathy is a well-documented entity in which numerous studies have shown a frequent but not constant relationship to excess dose or reduced fractionation [2]. Although analysis of the treatment techniques is always difficult, it must be attempted when multiple fields and possible junctional factors may potentially account for doses far in excess of the accepted tolerance of the spinal cord [l].
Refnences From the Neurology Service, Veterans Administration Hospital, Portland, OR 97201.
1. Lunbert PM:Radiation myelopathy of the thoracic spinal cord in long term survivors treated with radical radiotherapy using conventional fractionation. Cancer 41:1751-1760, 1978 2. Wara WM,Phillips TL,Sheline GE, et al: Radiation tolerance of the spinal cord. Cancer 35:1558-1562, 1075
From the Department of Radiation Therapy, The Medical College of Wisconsin, 8 7 0 0 W Wisconsin Ave. Milwaukee. W I 53226.
106 Annals of Neurology Vol 5
No 1 January 1979
bined but not by separate removal of amygdah and hippocampus. Science 273:297-298, 1978 5 . Penfield W, Mathieson G: Memory. Arch Neurol3 1: 145-154, 1974
6. Smith CM, Swash M: Possible biochemical bask of memory
disorder in Alzheimer disease (hypothesis). Ann Neurol 3:471-473, 1978
House Dogs and Multiple Sclerosis Luis Garcia-Buiiuel, MD The paper by Dr Stuart Cook and his associates (Further evidence of a possible association between house dogs and multiple sclerosis. Ann Neurol 3:141-143, 1978), postulating a relationship between ownership of indoor dogs and multiple sclerosis, reports an unusually high incidence of neurological illness among dogs owned by both patients with multiple sclerosis (18%) and controls (1 1%). In a survey of our outpatients, none of 17 patients with multiple sclerosis had owned a dog with signs of neurological disorder, and of 65 individuals with other problems, only 1 (1.5%) could recall ever having a dog so afflicted. The high incidence of neurological illness among the dogs from the control group in the study by Cook e t al suggests the possibility that these dogs, as well as those from the multiple sclerosis group, had increased exposure to some environmental factor. Because the controls were selected from households in the same neighborhoods as their multiple sclerosis counterparts, the implication might be that these areas represented clusters of increased exposure for both the dogs and their owners and that shared exposure to a similar agent occurred, rather than transmission from dog to human.
Postirradiation Myelopathy in Children -
Larry E. Kun,
MD
The suggestion of Sundaresan et al (Radiation myelopathy in children, Ann Neurol 447-50, 1978) that children demonstrate low spinal cord tolerance to irradiation may be seriously questioned. O n e must cautiously analyze developments following radiotherapy with regard to the specific details of treatment. All 3 patients presented by Dr Sundaresan were treated with craniospinal irradiation, o n e of the most complex treatment techniques in the radiotherapeutic armamentarium. Usually such patients are treated with at least three fields: two opposed lateral fields encompassing the cranium and upper cervical cord in continuity and a single posterior field that includes the lower cervical through sacral spinal canal. The technique requires immobilization in the prone position and daily reproducibility of treatment fields; furthermore, the joining of the two lateral fields with the posterior field may invite potential “overlap” or “skip” volumes due to the dosimetry involved. Careful review of the details of treatment for the reported patients is imperative before one assumes that the doses listed in the radiation therapy summary accurately reflect the doses delivered in specific areas of the spinal cord. Indeed, the level of myelopathy reported in the first 2 patients strongly suggests potential overlap or junctional overdosage in the midcervical spine where the lateral fields adjoin the posterior spinal field. The third patient, who had overt central nervous system leukemia, signs of methotrexate encephalopathy, and fungal meningitis at autopsy, showed so many variables that any conclusion as to the cause of her neurological signs is only speculative. Postirradiation myelopathy is a well-documented entity in which numerous studies have shown a frequent but not constant relationship to excess dose or reduced fractionation [2]. Although analysis of the treatment techniques is always difficult, it must be attempted when multiple fields and possible junctional factors may potentially account for doses far in excess of the accepted tolerance of the spinal cord [l].
Refnences From the Neurology Service, Veterans Administration Hospital, Portland, OR 97201.
1. Lunbert PM:Radiation myelopathy of the thoracic spinal cord in long term survivors treated with radical radiotherapy using conventional fractionation. Cancer 41:1751-1760, 1978 2. Wara WM,Phillips TL,Sheline GE, et al: Radiation tolerance of the spinal cord. Cancer 35:1558-1562, 1075
From the Department of Radiation Therapy, The Medical College of Wisconsin, 8 7 0 0 W Wisconsin Ave. Milwaukee. W I 53226.
106 Annals of Neurology Vol 5
No 1 January 1979
