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Abstract
Onset of dementia before 65 years of age is termed as
young-onset dementia (YOD). Very little literature exists
regarding the clinical features and diagnoses of dementia
in younger individuals. We present a case series of four
patients of age 10 to 23 years with severe dementia within
18 months of clinical onset (rapidly progressive dementia).
Three patients had generalised periodic complexes typical
of subacute sclerosing panencephalitis (SSPE) on
electroencephalogram (EEG). All patients had elevated
cerebrospinal fluid (CSF) IgG measles antibodies. Our case
series highlights that SSPE is an important cause of rapidly
progressive YOD in developing countries like India.
Keywords: Young-onset dementia, Subacute sclerosing
panencephalitis, Electroencephalogram.
Introduction
Subacute sclerosing panencephalitis (SSPE) is caused by a
mutated measles virus and is characterised by cognitive
deterioration, motor decline and myoclonus.
1
The onset is
between 5 and 15 years of age with a progressive
downhill course leading to death within two to four years.
Though the incidence of SSPE has declined substantially
after the introduction of an effective measles vaccine, the
annual incidence of SSPE is still quite high but variable in
developing countries.
2
Rapidly progressive global
cognitive decline leading to severe dementia or death is a
frequent presentation of SSPE. Severe dementia or death
within 18 months of clinical onset is termed rapidly
progressive dementia.
3
We present a profile of four
patients of SSPE presenting as rapidly progressive young-
onset dementia (RP-YOD). SSPE is an important cause of
RP-YOD in developing countries as opposed to other
causes seen in the developed countries.
Case-1
A 23-year-old carpenter presented with progressive
cognitive decline for the preceding two years, change in
personality since one year, disinhibited behaviour since
six months and getting lost in familiar surroundings since
three months. The patient was in his usual state of health
two years ago when his relatives noticed that he had
become apathetic, did not interact with relatives and had
become inattentive. He was not able to calculate money
and render appropriate change. He could not use tools
and, hence, was not able to work and had given up his job.
There were episodes when he would come out of the
bathroom without clothes. Before presenting, he was not
able to reach his home and was found wandering in the
market. There was no history of forgetfulness, language
disturbances, delusions, hallucinations, myoclonic jerks,
Vol. 63, No. 7, July 2013
921
CASE SERIES
Subacute sclerosing panencephalitis presenting as rapidly
progressive young-onset dementia
Rahul Tryambak Chakor, Nandanavana Subbareddy Santosh
Department of Neurology, Topiwala National Medical College, BYL Nair
Charitable Hospital, Mumbai Central, Mumbai, India.
Correspondence: Rahul Tryambak Chakor. Email: drchakorrt@yahoo.com.in
Figure-1: Flair axial magnetic resonance imaging of Case-1 showing confluent
symmetrical white mater hyperintensity in bilateral periventricular region reaching up
to the subcortical regions. It appears equally predominant in the anterior as well as
posterior regions. The ventricles appear a little prominent.
fever, headache, vomiting or head injury. There was no
family history of similar complaints. He had measles at
four years of age and had not received any vaccination.
His general physical examination was unremarkable.
Higher mental function (HMF) examination revealed poor
attention, impaired abstract thinking and judgment. Mini-
mental status examination (MMSE) score was 16/30 (lost
six points in orientation, five in calculations, and one point
each in reading, writing and construction). Frontal
assessment battery (FAB) score was 8/18 (lost three points
each in similarities and lexical fluency, one point each in
motor programming and conflicting instructions, and two
points in go-no go test). He had difficulty in clock drawing.
There was ideational and ideomotor apraxia. He had
alexia, agraphia, acalculia but no finger agnosia,
prosopagnosia, or visual agnosias. Cranial nerve
examination revealed right hemianopia. Rest of the
neurologic examination was normal. Magnetic resonance
imaging (MRI) of the brain revealed symmetric T2 and Flair
hyper-intense areas in the bilateral frontal and parieto-
occipital white matter (Figure-1). Electroencephalogram
(EEG) showed periodic lateralised epileptiform discharges
(PLEDs) from the left temporo-parietal region (Figure-2).
Cerebrospinal fluid (CSF) IgG measles antibody was 4.350
IU /ml (N < 0.08).
Case-2
A 14-year-old student presented with deteriorating
school performance for three months, and aggressive
behaviour and getting lost in familiar environment since
one month. The patient was apparently normal three
months earlier when the teachers noticed deteriorating
scholastic performance. He could not do arithmetic
calculations, and was not able to answer simple
questions. He was not able to grasp lessons taught in the
class. Once he had lost way while going to school. His
friends complained that he had become aggressive and
would quarrel on petty issues. He used to forget where his
books were kept and had difficulty in passing on the
messages told to him. There was no history of language
disturbances, delusions, hallucinations, myoclonic jerks,
fever, headache, vomiting or head injury. There was no
family history of similar complaints. He had received
measles immunisation and did not have measles.
HMF examination revealed poor attention, impaired
abstract thinking and judgement. MMSE score was 14/30
(lost seven points in orientation, four points in calculation,
three points in recall, and one point each in construction
and writing). FAB score was 3/18 (lost three points each in
similarities, lexical fluency, motor programming,
conflicting instructions & go-no go test). Rest of the
neurological examination was normal. EEG showed
periodic discharges of slow waves intermixed with sharp
waves of 1-2 seconds' duration every 10 seconds without
clinical myoclonus (Figure-3). MRI of the brain was normal.
CSF IgG measles antibody was 4.88 IU /ml.
Case-3
An 18-year-old girl presented with apathetic behaviour
for six months, disinhibited behaviour and myoclonus
since three months. She was apparently normal six
months earlier when it was noticed that she had become
less interested in going to work and in doing household
chores. She was apathetic, less talkative and less
interactive with family members. Three months later, she
developed sudden jerky movements of hands with
objects dropping, and sudden turning of the head
occurring at regular intervals several times a minute.
Subsequently, she developed disinhibited behaviour and
inappropriate micturition. There was no family history of
J Pak Med Assoc
922 R. T. Chakor, N. S. Santosh
Figure-2: Electroencephalogram of Case-1 showing periodic lateralised epileptiform
discharges from the left temporo-parietal region.
Figure-3: Electroencephalogram of Case-2 showing periodic complexes of slow waves
intermixed with sharp waves every 10 seconds.
similar complaints. There was no history of forgetfulness,
language disturbances, delusions, hallucinations, fever,
headache, vomiting or head injury. She had measles at the
age of two, and had not received any vaccination.
HMF examination revealed poor attention span, impaired
judgement and abstract thinking. MMSE score was 8/30
(lost nine points in orientation, three points in recall, five
points in calculation, one point each in reading, writing
and construction, and two points in three-stage
command). FAB score was 2/18 (lost three points each in
similarities, lexical fluency, motor programming,
conflicting instructions go-no go and one point in
prehension behaviour). Other detailed lobar functions
could not be performed due to poor attention span. Rest
of the neurological examination was normal. She had
myoclonus time locked with EEG paroxysms of periodic
complexes of slow waves intermixed with sharp waves
every 5 seconds (Figure-4). MRI brain showed T2
hyperintensities in bilateral frontal and fronto-parietal
cortical and subcortical regions. CSF IgG measles
antibodies were 4.693 IU/ml.
Case-4
A 10-year-old boy presented with deteriorating school
performance for eight months, apathetic behaviour,
muttering to self, getting lost in familiar environment and
myoclonus since the preceding six months. He was
apparently normal eight months earlier, when it was
noticed that his school performance had deteriorated and
he could not answer simple mathematics which he was
able to do so earlier. The teachers also complained that he
was less attentive. Over the next two months, he became
less interested in going to school and used to get lost
while going to school. He became apathetic, used to
remain aloof and was found muttering to self. There was
no history of language disturbances, delusions,
hallucinations, fever, headache, vomiting or head injury.
There was no family history of similar complaints. He had
measles at the age of two, and had not received any
vaccination.
On examination, attention and comprehension were
severely impaired for detailed HMF testing and MMSE.
FAB score was 2/18 (lost three points each in similarities,
lexical fluency, motor programming, conflicting
instructions, go-no go and one point in prehension
behaviour). There were bilateral pyramidal signs on motor
examination. Rest of the neurological examination was
normal. He had myoclonus time locked with EEG
paroxysms of slow waves intermixed with sharp waves
every 3.5 to 4 seconds. On MRI brain, there were T2
hyperintensities in the right temporo-occipital and right
posterior parietal regions. CSF IgG measles antibodies
were 4.909 IU/ml.
Discussion
All the patients had rapidly progressive cognitive decline
with predominant frontal lobe dysfunction. Case 1
presented with cognitive decline interfering with his work;
cases 2 and 4 had deteriorating school performance; and
case 3 had initial apathetic behaviour followed by
disinhibited behaviour. All patients had an RP-YOD with
onset between 10 to 23 years of age (mean age 16.25±5.56
years). There was no family history of similar complaints.
Three of the four patients (75%) had history of measles and
only one (25%) patient had received immunisation. Three
(75%) patients had EEG with generalised periodic
complexes of slow waves intermixed with sharp waves
every 3 to 10 seconds characteristic of SSPE. Case one had
PLEDs, which are not specific to SSPE. Periodic complexes
in SSPE may be grossly asymmetrical and resemble PLEDs
in some montages. All patients had elevated CSF IgG
measles antibodies.
Vol. 63, No. 7, July 2013
Subacute sclerosing panencephalitis presenting as rapidly progressive young-onset dementia 923
Figure-4: Electroencephalogram of Case-3 showing periodic complexes of slow waves
intermixed with sharp waves every 6 to 7 seconds.
Figure-5: Electroencephalogram of Case-4 showing periodic complexes of slow waves
intermixed with sharp waves every 3 seconds.
Conventionally, dementia with onset before 65 years of
age is regarded as young-onset dementia (YOD).
4
Very
little literature exists regarding the clinical features and
diagnoses in younger individuals experiencing rapidly
progressive dementia, primarily due to the rarity of the
presentation. In a study of RP-YOD by Kelley et al, the age
of onset and presentation of dementia was after 20 years
of age.
3
There was no case of SSPE in their study. In
another study of YOD with onset between 17-45 years
Kelley et al found that the cause of dementia varied with
age with inborn errors of metabolism being more
common before age 30 years, and neurodegenerative
aetiologies being more common after age 35.
5
In their
study, the aetiology of YOD was neurodegenerative in
31.1%, autoimmune or inflammatory in 21.3%,
metabolic in 10.6%, unknown in 18.7% and infectious in
4.7%. Prion disease,
6
human immunodeficiency virus
(HIV) dementia,
3
progressive multifocal
leukoencephalopathy
2
were the various infectious
aetiologies.
5
They did not have any case of SSPE as a
cause of YOD. Our case series highlights that SSPE is an
important cause of YOD, especially RP-YOD, in
developing countries like India.
The existence of the SSPE in high number in India could
be multifactorial — improper vaccine coverage, failure of
cold chain maintenance or circulating atypical measles
virus strain can be the causes.
6
It is notable that only one
patient in this series had received immunisation.
Conclusion
In developing countries, RP-YOD should alert one for the
possibility of SSPE. Non-immunisation is an important
factor for the existence of SSPE in developing countries.
References
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subacute sclerosing panencephalitis: clinical profile of 39 patients
from a tertiary care centre. J Neurol Neurosurg Psychiatry 2006;
77: 630-3.
2. Garg RK. Subacute sclerosing panencephalitis. Postgrad Med J
2002; 78: 63-70.
3. Kelley BJ, Boeve BF, Josephs KA. Rapidly progressive young-onset
dementia. Cogn Behav Neurol 2009; 22: 22-7.
4. Rossor MN, Fox NC, Mummery CJ, Schott JM, Warren JD. The
diagnosis of young-onset dementia. Lancet Neurol 2010; 9: 793-
806.
5. Kelley BJ, Boeve BF, Josephs KA. Young-onset dementia:
demographic and etiologic characteristics of 235 patients. Arch
Neurol 2008; 65: 1502-8.
6. Mishra B, Kakkar N, Ratho RK, Singhi P, Prabhakar S. Changing
trend of SSPE over a period of ten years. Indian J Public Health
2005; 49: 235-7.
J Pak Med Assoc
924 R. T. Chakor, N. S. Santosh
