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Course and outcome of acute cerebellar ataxia.

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Course and Outcome
of Acute Cerebellar Ataxia
Anne M. Connolly, MD,” W. Edwin Dodson, MD,” Arthur L. Prensky, MD,” and Robert S. Rust, MD?$
We report a study of 73 consecutive children with acute cerebellar ataxia, representing all of the children evaluated
at St. Louis Children’s Hospital during a 23-year-period to whom this diagnosis could appropriately be assigned.
Twenty-six percent had chickenpox, 52% had other illnesses that were presumed to be viral, and in 3% the ataxia
was related to immunization. Nineteen percent had no definite prodrome. Sixty children were followed for 4 months
or longer after onset of their ataxia (mean, 7.4 f 6.0 years). Ninety-one percent (55160)of these, including all children
with chickenpox, recovered completely from ataxia. Eighty-nine percent (39/44)of the children with non-varicellarelated ataxia recovered completely from the ataxia, a much better rate of recovery than what was found in prior
large studies. One fifth of the children followed for more than 4 months experienced transient behavioral or intellectual
difficulties, but only 5 of the 60 children demonstrated sustained learning problems. This study represents the largest
reported series of acute cerebellar ataxia and the most complete characterization of the clinical features and outcome
of this illness.
Connolly AM, Dodson WE, Prensky AL, Rust RS. Course and outcome of
acute cerebellar ataxia. Ann Neurol 1994;35:673-679
Acute cerebellar ataxia (ACA) is a sudden disturbance
of gait and balance that may develop in children after
a wide variety of illnesses, usually viral and most commonly varicella. Batton’s initial account ( 1705) described the usual clinical course: “A child perfectly
healthy and of good intellectual development is taken
ill with some acute febrile disease. The child is kept in
bed and seems to be making a normal convalescence.
When, however, the child is sat up in bed it is found
that he is unable to maintain his balance” [l). Between
1920 and 1757 the clinical appearance and outcome of
ACA were characterized in a series of articles [2-71,
culminating in Weiss and Carter’s classic study (81. The
prognosis varied considerably in these reports. Weiss
and Carter documented permanent neurological in jury
in one third of non-varicella-related ACA, but smaller
studies that included post-varicella ACA suggested a
better prognosis [4-6, y}. We undertook a comprehensive study of children with ACA in a major urban
teaching hospital in order to address the following two
questions: (1) What is the long-term morbidity of
ACA? (2) Are there any clinical or laboratory predictors of outcome?
Materials and Methods
The medical records of all children evaluated for ataxia at
the St. Louis Children’s Hospital between January 1, 1967
From the *Depanments of Pediatrics and Neurology, Washington
University Schbol of Medicine, St. Louis; the tDep2ments of Neurology and Pediatrics. University of Wisconsin, Madison, W1; and
the iMcDonnel1Center for Studies of Higher Brain Function, Washington University, Sr. Louis, hI0.
and December 31, 1989 were reviewed. The diagnosis of
ACA was assigned to 74 children who had an acute onset of
gait ataxia but no evidence, after a thorough evaluation, for
tumor, abscess, polyneuritis, meningitis, intoxication, metabolic disease, or familiaVdegenerative disorders as the cause
of t h e ataxia. ACA was disringished from other forms of
viral-associated, presumed central nervous system (CNS) inflammation (encephalitis, acute disseminated encephalomyelitis) by the absence of prominent meningismus or neurological abnormalities not referable to the rhombencephalon. N o
patients with seizures or significant alteration in mental status
were included. In patients in whom ataxia recurred, extensive
metabolic evaluations were undertaken and the findings were
negative. We excluded 1 patient with probable varicellarelated, bilateral gait ataxia that improved but was complicated by the onset, some months later, of a pseudorecurrence
emphasized in one upper extremity; cerebellar astrocytoma
was diagnosed. No other unexpected illnesses were diagnosed on follow-up.
Follow-up information was obtained for 66 children at intervals ranging from 1 to 273 months after the onset of ataxia.
Forty-seven (71F) returned for an interim history and complete examination. An additional 19 (29%) had telephone
interviews and/or physical examinations by a local physician.
Sixty of the children were thoroughly reevaluated at more
than 4 months after the onsct of their ataxia and constitute
the outcome subgroup. The demographic and clinical characteristics studied included sex, race, age at presentation, duration of hospitalization, presence or absence of prodromal
Received -Tul 3.. 1993. and in revised form Oct 2 5 . AcceDted for
publication Oct 27, 1993.
Address correspondenceto Dr Rust, Universiry of Wisconsin School
h.ledicine,Departme,lt of Neurology--HG,54b,
Highland
Avenue, Madison, WI 53792.
of
Copyright 0 1994 by the American Neurological Association
673
Table 1 . Clinical Characterzstics at Onret of
n (% totabb
Age (yr)
Latency (days)
Latency range (days)
Fever (Fc)
Gait ataxia (average)
Severity = 3 ( 2 )
Severity = 2 (F)
Severity = 1 ((3)
Dysmetria ( 2 )
Truncal ataxia (%j
Nystagmus (q)
hute
Certbellar Ataxia bj SubguoupJ"
Varicella
"Viral"
Epstein-Barr
Virus
19 (26)
36 (49)
4.9 2 3.5
9.3 k 5.8
1-21
2.8
2.0 t 0.8
30.6
36.1
33.3
58.3
61
11.0
2 (2.6)
17.8 4.5
17.5 2 4.9
14-21
0
2.5 f 0.7
50
50
0
100
100
50
4.6 t 2.6
10.8 2 9.8
2-2 1
5.3
2.4 ? 0.8
56.6
31.6
15.8
68.4
74
10.5
"See text for definitions of subgroups.
'Parenrherical expressions in
row refer
to
Vaccine
Idiopathic
2 (2.6)
12.9 t 12.3
11.0 2 4.2
8-14
0
2.5 2 0.7
50
50
*
14 (19.2)
5.1 2 3.3
0
0
0
1.9 ? 0.7
21.4
50
28.6
71.4
78.6
21.4
0
100
50
0
percentage of entire p(Ipulation. Other percenrage expressions retier ro subgroups only.
illness, latency between prodrome and onset of ataxia, presence of fever at presentation, truncal ataxia, gait ataxia, nystagmus, cranial nerve palsy, and long-tract signs. Gait abnormality was judged as mild (unsteady or poor tandem gait),
moderate (unable to perform tandem gait), or severe (unable
to walk). Laboratory variables included blood cell count, cerebrospinal fluid (CSF) protein concentration and cell count,
IgG index, neuroimaging results, anti electroencephalographic (EEG) results. Outcome measures included presence
or absence of ataxia, recurrence of symptoms, time of recovery of normal gait and of fine motor skills, school problems,
behavioral problems, and speech or hearing difficulties. Correlation of data was established using a x' test for all categorical variables and linear regression (nonparametric statistics)
with a two-tailed Student's t test for continuous variables.
Given the large number of correlations, a Bonferroni correction was applied with significance assigned where p 5 0.004.
Results
Presentation
The 73 children who satisfied our entry criteria represented approximately 0.4% of all patients evaluated
for neurological problems during the 23-year study interval. The clinical features at onset are detailed in Table 1. The mean age at presentation was 5.37 k 4.00
years; the distribution of ages (Fig 1) was clearly
skewed, with 60% of children 2 to 4 years old at onset.
The age distribution was quite similar for ACA occurring after vaxicella, after viral syndromes, or without
prodrome. Epstein-Barr virus (EBV) and vaccinationrelated ACA were found in older children. The youngest child developed ACA after varicella at the age of
1.1 years and the oldest had well-documented ACA
after mononucleosis at the age of 21 years. Fifty-seven
percent were boys and 43($ were girls. Seventy percent were white and 30%: black, almost exactly the
typical racial mixture of our inpatient service. Age,
race, and sex showed no significant correlation with
674 Annals of Neurology Vol 35 No 6 June 1994
1z
L
I
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
FIR. 1 . Distrzbution of patient age ut the on.ret of-ataxia
clinical presentation (except as noted below) or
outcome.
Prodromal illnesses were identified in 57 children
( 7 8 q . ; 26q had chickenpox and 52% had other presumed viral illnesses). Among 36 children with presumed viral illnesses other than varicella, 5 had gastrointestinal and 3 1 had upper respiratory symptoms.
Twenty-four had viral cultures performed and/or titers
measured, and EBV was the only specific agent identified (n = 2). Two patients developed ataxia after immunization, one for smallpox and one for measles; 14
children (19.2%) had no recognized prodrome.
Fever was present at the onset of ataxia in only 2
patients (2.7%), one with varicella and one with a viral
syndrome. The latency from prodromal illness to the
onset of ataxia averaged 9.9 k 7.9 days (range, 1-43
days) for all patients with identifiable causes or prodromata. Latency was somewhat longer after EBV infection than after other known or presumed viral illnesses
or immunizations. Ataxia was strongly emphasized or
Table 2. Laboratoq Vahes ut Onset of Acute Cerebellar Ataxia, b j Subgroups
WBC x 103(X ir SD)
WBC Range ( x 10 ’)
WBC > 10 X 10”(g)
Lymph Seg > 1 0 (VY
CSF protein (pg/dl) (n)
CSF protein range (kg/dl)
CSF protein > 40 (%)
CSF WBCimm’ (X -t SD)
CSF WBCimm’ range
CSF WBC > 6;mm3 (%)
’Lymph: Seg
WBC
=
3>
Varicella
“Viral”
8.0 ? 2.:
4.5-13.0
23
100
21 2 13 (18)
10.6 ? 3.6
5.8-22.0
7-49
6
17 -_fr 26
0-107
50
Epstein-Barr
Virus
49
92
31 2 25 (34)
10-99
26.5
14 t 23
0-99
46
6.8 i 0.6
6.4-7.2
0
100
Vaccine
Idiopathic
-
9.9 ? 2.0
6.8-15.8
36
100
21 ? 12 (14)
7-4 j
7.1
0
-
29 f 11 ( 2 )
36 (1)
36
21-36
0
0
0
22.1
1-2
-
0
0
7’9
0- 107
29
1 . 0 (c$) indicates prrcenr of subgroup with preponderance of lymphocytes in WHC differential.
white blood cell; CSF = cerebrospinal fluid; SD = standard deviation.
confined t o ataxia of gait. The severity of gait ataxia
(see above) was judged to be mild in 26% (19/73j,
moderate in 4057, (29/71), and severe in 347{ (25173)
of children. I t was worse in patients with ataxia related
to varicella, EBV, and vaccination, as 57r4 (lii2.3) of
these children were unable to walk. Only 3 1 (1 1i 3 6 )
of children with an unspecified viral illness and 21%
(3114) of children without a prodrome had such a severe gait abnormality.
Associated neurological findings were frequently encountered. Truncal ataxia and dysmetria were the most
common signs, present in 7 0 9 and 63% of all patients,
respectively. In most, truncal ataxia was emphasized
during walking as compared to sitting, thus representing a manifestation of gait ataxia. It was somewhat less
common after occurrence of a nonspecific viral prodrome or vaccination than in ACA following varicella,
EBV infection, or no prodrome (see Table 1). Dysmetria was present in all patients with EBV- or vaccination-related ataxia and about two thirds of those with
ACA from other etiological categories (see Table I).
Nystagmus (usually gaze-paretic) was present in 13.7%;
cranial nerve palsies (abducens, facial and/or glossopharyngeal), in 6.8%; and corticospinal tract signs, in
5.4%. Eighty percent (16120) of the children with nystagmus or cranial nerve palsies were boys. Two had
mild meningismus and 1 had mild bilateral footdrop.
The laboratory data are shown in Table 2. White
blood cell (WBC) counts were usually normal (mean,
9.0 ? 4.5 x lo3), but were elevated in roughly half
of the patients wirh “postviral” ataxia. Four children
had WBC counts higher than 15,000. In nearly every
patient the WBCs showed lymphocytic predominance.
Sixty-nine children had lumbar punctures. The CSF
protein concentration averaged 24
19 pg/dl (range,
7-99 pgidl) and tended to be higher in those with
nonvaricella postviral disease. The CSF protein level
was higher than 40 pgidl in 26.5% of these patients,
+
and was higher in children with neurological signs
other than ataxia (mean, 32 ? 19 kg/dl); 309? of these
children had CSF protein values above 45 kg/dl.
The mean WBC count in the CSF was 10.8 i 16.6
WBCsimrnj (range, 0- 107imm’). Pleocytosis (> 5
WBCs/mm’) was present in approximately half of the
children. Seventy-six percent of children had roughly
equal numbers of granulocytes and lymphocytes, 20%
had a lymphocytic predominance, and only 1 child
( 3 5 ) had granulocytic predominance. The CSF IgG
ratio (11 = 14) was elevated i n 7 q and the CSFiserum
IgG index (n = 8 ) was elevated in 5057, when compared to normal childhood values 1l0j. Oligoclonal
bands were present in 10 to 17%. All bacterial (n =
69) and viral (n = 21) CSF cultures were negative.
Brain imaging was performed in 52 children (71%
of the entire group). Thirty-seven had coniputed tomograms, 9 had magnetic resonance (MR) scans, 8 had
radionuclide studies, and 6 had pneumoencephalograms. All of these studies were normal with the exception of one MR scan. This scan showed an area of
increased T2-weighted resonance in the left cerebellar
hemisphere, which persisted but had improved somewhat on a repeat scan 1 month later. This child had
symmetrical, moderate ataxia of gait at presentation
and was normal on follow-up.
EEGs were obtained for 26 children and the findings
were abnormal in 12 (46%). Nine children had mild
slowing and 3 exhibited frank electrographic epileptogenic activity. No patients were observed to have clinical seizures.
Oatcome
Sixty children (82%) were followed for 4 months or
longer (mean, 7.38
6.0 years; range, 0.4-22.6 years)
and constitute our outcome study group. The outcome
data are shown in Table 3. The duration of follow-up
is depicted graphically in Figure 2. Fifty-three of these
*
Connolly et al: Acute Cerebellar Ataxia
675
Table 3, Clinical Follow-np Data (4-2.35 Month), by Subgroup3
Epstein-Barr
n
Mean follow-up (yr)
Follow-up range (yr)
Mean time to nl gait (mo)
> 2 mo to nl gait (q)
Mean time to nl FM (rno)
> 2 mo to nl FM (%)
Behavioral abnormalities”(a)
Hearing abnormalities”(%)
Speech abnormalities”(%>)
Varicelta
“Viral”
16
9.1
1.8
29
Virus
2
5.3
7.2 ? 6.1
?
19.6
1.8
0.4 f 22.6
*
2.1
18
1.2 f 0.4
3.3
33
?
3.4
1.8
%
1.4
0
31
6
14
24
19
14
2
7.0
*
1.9
5.7 2 8.3
2.0 f 0
0
1.0 2 0
0
50
0
0
7
Vaccine
Idiopathic
2
8.5
11
7.0
0.5
3.2
50
1.7
%
9.1
%
15.3
-
40
0
0
0
18
0
18
2.8
&
?
?
7.8
20.9
2.0
* 2.0
‘Abnormalities as defined in text.
nl = normal; FM
loo
=
fine motor.
A
80
8
20
I
O
5 10 20
40
60
L
80 100 120 140 160
180 200
L
220 240 260 280 300
Followup (mos.)
40
20
0
4
Duration of Ataxia (mos.)
Fig 2. Duration OffOLlow-up.
Fig 3. Duration of gait ataxia.
patients recovered completely from ataxia, including
all children whose ataxia followed varicella, EBV infection, or vaccination. The time to recovery or normal
gait was determined in 45 children and is shown in
Figure 3. Full gait recovery required an average of
slightly more than 2 months in children with ataxia
related to varicella or EBV, but 18% of these children
required 3 months or more to return to normal (range,
2-108 weeks). Although maximal gait dysfunction was
generally less severe, children with nonspecific viral
prodromata, and especially those who did not have any
prodromal illness, required more time for gait recovery
(averaging 3.2 months; range, 1 week-7 years; p <
0.004) than did children with ataxia associated with
varicella. Half of the children with ACA but no definite
preceding viral illness required more than 3 months to
recover.
Among children followed for 4 months or more,
prolonged or permanent gait dysfunction (follow-up >
4 months) was found only in children without a preceding viral illness or children whose preceding illness
constituted a nonspecific respiratory or gastrointestinal
illness presumed to be caused by a virus (Table 4).
Mild or moderate gait abnormalities were found in
10.3% (3/29) of children with a nonspecific viral illness. These abnormalities persisted for 2.7 years or
more in 2 of these children. Among children without
a preceding illness, 18.29 (2111) had persistent gait
abnormalities; in 1, these abnormalities were of moderate severity and were still present more than 20 years
after onset. Six children were followed for only 1 to 4
months. Four of them recovered completely; 2 (1 with
n o prodrome and 1 with a nonspecific viral illness)
had mild gait abnormalities at final follow-up. Seven
children were lost to follow-up at discharge, which occurred 2 to 13 days after admittance (Table 5). Two
recovered completely and the rest recovered substantially and were able to walk at the time of discharge.
The time required for recovery of fine motor skills
was ascertained in 39 of 48 children who exhibited
abnormalities, and averaged 1.7 I
1.3 months. Recovery was faster in those with ACA related to varicella
or EBV (averaging 1 month, none more than 2
months) than in those with ACA related to a nonspe-
676 Annals of Neurology Vol 35 No 6 June 1994
Table 4. Summary of Children with Disabilitya
Patient No.
Age (yrj
1.4
1
2
3
4.5
5. I
4
7.2
5
10.3
RaceiSex
Prodrome
Gait-Onset
Gait FU (DOFj
Other Deficits
WIM
WIF
Bi M
BIF
WIM
NSV
Severe
Severe
Severe
Mild
Severe
Mild (2.74 yrj
Moderate ( 1 1 yr)
Moderate (20.64 yr)
Swallowing
Reading
Articulation
NSV
None
None
N SV
Mild (13 mo)
Mild (4.5 mo)
'See text for definition of ataxia severity. None of these patients had recurrences.
NSV = nonspecific illness, presumed viral; Gait-Onset
duration of follow-up.
Tuble 5 . Children with N o Follow-up i n
Patient
No.
6
Age
(vr)
?
1.3
1.6
8
2.2
9
4.5
6.1
7.3
10
11
12
12.0
Ataxia
URI
Severe
Severe
Moderate
Severe
Moderate
Mild
Moderate
URI
upper respiratory illness; VAR
testinal iiiness.
~
gait disturbance at presentation; Gait FU
7)
Condition at Discharge
(Day of Discharge)
Prodrome
VAR
GI
VAR
URI
URI
None
=
=
=
Walking (7)
Walking (13)
Normal (4)
Walking ( 6 )
Walking (9)
Normal (2)
Walking ( 4 )
varicella; GI
:
gastroin-
cific viral cause (averaging nearly 2 months, 1 4 q requiring G months or more; p < 0.005) or children
without prodrome (averaging nearly 3 months, 40%)
requiring 6 months o r more; p < 0.003).
Behavioral changes coincident with the ataxia and
noted by the parents included marked irritability, hyperactivity, and social withdrawal. These changes persisted for up to 1 year in 2 children and did not resolve
in a third child (Patient 2, see Table 4 ) who had persistent gait disturbance and mental retardation 4.5 years
after onset of ACA. Subtle behavioral changes (mild
irritability, moodiness, whining) were noted for weeks
to months after the onset of ACA in 18 to 505? of
children, including 3 1% of children with varicellarelated ACA. Approximately 20% of the children experienced minor transient school difficulties after
ACA, on the basis of either behavioral or learning difficulties. Nonetheless, most children achieved average
or above-average grades. Hearing problems were
found in 6% of children with ACA associated with
varicella and 7% of those with nonspecific prodromata
on follow-up. Speech difficulties including articulation
problems (7 children) and stuttering (2 children) were
found in 15%, with a similar frequency in each of the
larger etiological groups. One child developed common migraine shortly after onset of ACA.
Four children (2 girls and 2 boys) experienced recurrences, usually after another presumed viral illness.
None had evidence, after extensive evaluation, for
=
gait disturbance at follow-up; DOF
=
metabolic disea5es known to produce recurrent ataxia.
The youngest was a 2.8-year-old girl who experienced
three episodes of moderate ataxia, each separated by
approximately 1 year of normal function. Four years
after her last recurrence she had attention deficit/
hyperactivity disorder and was failing third grade. Two
children (a 4.7-year-old boy and a 7.3-year-old girl)
had mild or moderate ACA that resolved in a week
but recurred 1 month later; recovery required a week
in 1 but 12 months in the other. Both were normal
.08 to 12.5 years later.
An 8.8-year-old boy developed severe ACA that resolved in a few weeks; he experienced six mild episodes (clumsy gait and hand tremulousness) over the
ensuing 14 months. Evaluation 2 years after the last
recurrence showed hypotonia and mild right appendicular dysmetria. Nothing in the presentation or initial
recovery period distinguished children who experienced recurrences from those who did not except for
a longer latency between the prodrome and development of the initial attack of ataxia. Thus, the longer
the latency, the more likely the children were to have
a recurrence ( p 5 0.0001).
Five children followed longer than 4 months had
persistent gait disturbance. Their clinical histories are
summarized in Table 4. Each of the various outcome
variables was analyzed in relationship to presentation
variables in order to determine which might predict
persistent deficits. Covariation of outcome variables
was also analyzed. No child with ACA associated with
varicella had any motor disability at the final follow-up
evaluation, as compared to 13.6% of children with
ACA related to other illnesses ( p 5 0.01). Gait abnormalities ranged on follow-up from mild (n = 3 ) to
moderate (n = 2). One patient was mentally retarded
and 1 had significant mechanical speech difficulties on
follow-up, as noted above. Race, sex, fever, and laboratory values did not predict outcome.
Although truncal ataxia ( p 5 0.05) and nystagmus
(t) 5 0.01) were more common among patients who
subsequently had disability, they were not significant
predictors after Bonferroni correction was applied.
The severity of gait ataxia (but not the truncal ataxia)
Connolly et al: Acute Cerebellar Ataxia
677
at presentation correlated with the time required to
recover normal gait ( p 5 0.0004), but did not predict
disability in the 5 children who had persistent deficits.
The amount of time required for recovery of normal
fine motor skills correlated with behavior and speech
outcomes. h€ore prolonged recovery of fine motor
skills indicated a greater likelihood of behavioral problems on follow-up ( p 5 0.001) and speech difficulties
( p 5 0.003). This included most of the children who
had slower than average rates of recovery after varicella-related ACA. Slower gait recovery was also associated with an increased risk of hearing difficulties
( p 5 0.003), especially in the varicella subgroup
( p zz 0.0008). Several additional correlations were observed among outcome variables. Speech difficulties
correlated with degree of maximal gait disability ( p 5
0.001 ); speech and behavioral difficulties covaried ( p
5 0.004).
Discussion
Batton, in his important early review of ataxia in childhood [ 1], first recognized the clinical features of ACA.
H e described 5 children with a mean age of 4 years 9
months at the onset of gait ataxia. Two had whooping
cough, 2 had measles, and 1 had scarlet fever as prodromal illnesses. On follow-up, 4 were normal and 1
child, who was followed for just 3 months, was able to
walk only a few steps without help. In 1921 Griffith
131 reviewed the cases of 31 patients with what he
called “acute cerebellar encephalitis” and noted that
about one fourth of these patients had mental defects
on follow-up. However, two characteristics of this population should be noted. Nineteen of the 31 had disturbed mentation; I 2 of these children were comatose
(1 for 7 weeks). Ten of these patients were unlikely to
have had ACA either as described by Batton or according to our criteria and experience.
In 1044 Klingman and Hodges {4] documented
complete recovery in 5 and slight persistent incoordination in 2 children with ACA. Shanks [93 found incomplete recovery in 4 of 17 children with ACA ( 3
deteriorated or died, 4 improved somewhat); the duration of follow-up was not reported. K n g and coauthors
171 described 9 ataxic children, 5 of whom fit Batton’s
clinical criteria for ACA. One of these was mentally
retarded and had persisent ataxia 9 years after ACA.
Blaw and Sheehan [63 reported recovery in 6 of 8
children with ACA but the duration of follow-up was
very brief.
Analysis of these early studies of ACA is complicated by the lack of a consistent clinical definition and
by brief or uncertain follow-up intervals. In 1959
Weiss and Carter [S) presented their classic study of
18 children with well-defined ACA. They excluded
children with exanthem-related ACA, particularly
those with varicella. Irritability, the only disturbance of
678 Annals of Neurology Vul 35 No 6 June 1994
mental status noted, was found in G children. Six of
the children had experienced abnormally slow development prior to the onset of ACA. Five were noted to
have abnormal rhythmic eye movements immediately
preceding the onset of gait ataxia. O n follow-up, 6 children (33q.I had persistent gait disturbance.
Our series is the largest series, with the longest follow-up, of children with ACA that has been published.
We designated ACA in children who were extensively
evaluated and to which rigorous exclusion criteria were
applied. The children retained in this study showed
remarkable clinical uniformity. The striking clinical
characteristic is acute ataxia emphasized in the gait (legs
and trunk). This suggests that the unknown dysfunction of chis illness is largely confined to the anterior
and posterior cerebellar lobes (or connections). Neocerebellar signs (especially dysmetria) were observed
in two thirds of the children, but were far less prominent than gait abnormalities. Vermal or paravermal
dysfunction was much less common. ACA is much
more likely to occur in young children, although it can
occur in older children or adults, particularly after EBV
infection or vaccination f 1I}.
Prior stuclies did not carefully determine rates of
recovery for each of the elements of dysfunction associated with ACA. The majority of our children recovered normal gait and fine motor control after 1 to 2
months but persistence of gait ataxia for 6 months did
not predict outcome and most of these patients also
recovered fully. A longer duration of the recovery
phase was found in patients with non-varicella-related
ataxia, especially after a nonspecific viral prodrome.
Patients with varicella-related ACA with slower rates
of recovery of fine motor skills were at higher risk for
mild behavioral abnormalities and hearing deficits. The
outcome in children followed for more than 4 months
was overwhelmingly fiavorable, with 9 1% recovering
completely. Among children followed for less than 4
months (n = 13), 6 showed complete recovery and 7
had substantially improved and were walking at the
time of final evaluation.
Several other findings in our study have not been
reported previously. It appears that boys are more
likely than girls to develop ACA, tend to have worse
gait dysfunction, and are at higher risk for associated
cranial nerve palsy andlor nystagmus. Patients with varicella-related ACA tend to have worse gait ataxia than
those with ACA after other illnesses, but these patients
show more rapid rates of recovery and virtually all appear to return to normal. Among the 14 children in
whom the determination was made, half showed evidence of CNS inflammation, with elevation of the
CSFiserum IgG index. Nonetheless, inflammatory
changes could be identified in the cerebellum in only
1 of 9 children who had MR scans, a finding that is
quite different from children with illnesses thought
to represent acute disseminated encephalomyelitis
(ADEM). Patients with ADEM usually demonstrate
areas of abnormally bright resonance on T2-weighting, often including the cerebellum { 12).
The more favorable outlook experienced by our patients, as compared to those of Weiss and Carter {S},
is in keeping with our clinical impression and is likely
to be related to at least three factors. First, most children are now protected by immunization from a number of childhood illnesses (especially measles and
whooping cough) that have been associated with more
severe forms of ACA. Second, in Weiss and Carter’s
series, 3 of the 6 patients who were disabled on followup were developmentally delayed prior to the onset of
ACA. Finally, we included patients with varicella into
our study and they experienced a uniformly good outcome, despite somewhat worse ataxia at onset. Nonetheless, even when this group is excluded, 88%) of children followed for more than 4 months recovered fully.
All children with EBV- or vaccination-related ACA
also recovered fully. Recurrences, seldom mentioned
in prior studies, were not rare in our series. All of
these children ultimately recovered normal gait; minor
abnormalities seen at follow-up in this group are detailed in Table 4.
Higher cortical dysfunction has not been very carefully investigated in studies of ACA. Maltz and Goldberg 1131 studied a select group of 15 children who
had recovered from ACA. Psychometric testing
showed no deficits of higher cognitive function at a
mean follow-up interval of 6 years. On the other hand,
fine motor coordination, as tested by the Purdue pegboard test, was poorer in patients than in control subjects. We documented mild speech and language difficulties in several of our patients. One patient was
mentally retarded on follow-up. A significant fraction
of our patients developed subtle changes in personality, behavior, and school performance after ACA.
These changes are reminiscent of the subtle changes
observed in some children after Sydenham’s chorea
[14}. As with Sydenharn’s chorea, some of our patients
had related difficulties prior to the onset of ataxia. In
others, ACA occurred at so young an age that premorbid behavioral and intellectual status could not accurately be evaluated. The possibility that ACA produces
higher cortical dysfunction remins a subject of important future consideration.
This study was supported in part by grants from the American Medical Association Education and Research Fund and the McDonnell
Center for Studies of Higher Brain Function (R.S.K.).
The secretarial assistance of Trisha Stanton and Therese Traut is
gratefully acknowledged.
Presented in part at the 17th meeting of the Child Neurology Society, Halifax, Nova Scoria, September 16, 1988.
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Connolly et al: Acute Cerebellar Ataxia 679
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