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Brainstem auditory evoked responses in jnad.

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eases including dermatomyositis, polyarteritis nodosa, and
SLE [l. 2, 41. Second, painful ophthalmoplegh is sometimes associated with serological abnormalities such as the
LE cell phenomenon and andnuclear antibodies without
other evidence of systemic disease [31.
References
1. Brenner BH. Shock JP:Proptwir secondary to systemic lupus
erythemntosus. Arch Ophthdmol 91:81-82, 1974
2. Burkhalter E: Unique presenauon of systemic lupus erythemamsus. Archrids Rheum 16428, 1973
3. Mnthew NT, Chandy J: Painful ophthnlmopkgh J Neurol Sci
11~243-2S6,1970
4. Wilkinmn LS, Panush RS: Exophthahos associated with systemic lupus ergthemorus. Arthritis Rheum 18:188-189,
1975
Brainstem Auditory
Evoked Restmnses in
JNAD
L
Keith H. Chiappa, MD,Sam K. Choi. MD,
and Robert R.Young, MD
In the paper by D o r f m et al (Dorfman LJ, Pedley TA,
Tharp BR,et al: Juvenile neuronxonal dystrophy: clinical,
elecuophysiological, and neuropathological features. Ann
Neurol 3:419-428, 1978) there are some unusud features
concerning brainstem auditory evoked responses in
juvenile neuroaxonal dystrophy WAD). The configuntion of the entire group of waveforms is not what one
usually sees, especially with a high-pass filter setting of 30
Hz.Waves I through 111 usually ride on an ascending
baseline slope that leads up to the even hlgher waves 1V
and V; in their Figure 5 (p 424), waves I through 111 progressively descend. Also, the shape of the IV-V complex is
unusually rounded and “humped.”
If one inverts the polarity of chat figure, as reproduced
here, the waves assume a much more normal configuration
and the interwave latencies remain normal. The only
Rmersd of po&rity of FigurP 5 , CZ positive up, showing
brainstem auditory far-firldevokedpotentialr in a patient with
JNAD, fmm the article DorfiAIln et a[.
s
1
problem, then, is that the absolute latency of wave I is too
short. We wonder whether a presweep delay was used,
especially since no stimulru artifact is visible in the
trace-or was this edited out? If the polarity in Figure 5 is
incorrectly oriented, the waves are incorrectly named and
the latencies wrong. There is reasonable debate concerning
the true polarity of cenain of the click-induced far-field
potentials because their source is not absolutely defined;
there should be no controversy about whether they are
relatively positive or negative at CZ compared with the ear.
Reply
Leslie J. Dorfman, M D
The polarity in the figure is correct. The initial 0.1 msec of
each trace, containing the stimulus artifact. was edired out
of the illustration (as indicated by the stimulus arrow) but
was included in the latency measurements. Inverting the
traces would not only be erroneous, it would also give
unreasonably short latencies [I, 21 for all five of the early
inverted wave peaks, including a“wave v’ latency of 4.50
rnsec. This poinn out one potential pitfall in overemphasizing interwave latency differences without due regard
for the absolute values of the individual wave latencies.
The minor variations in confqguation of the evoked potentials which disturb Dr Chiappa and his colleagues could
be due to abnormal impulse transmission in the brainstem
of this patient with JNAD. However, it seems unwise to
ascribe much significance to such slight variations without
better evidence. More likely, these merely represent contributions to the evoked potentials from pathological
low-frequency background electroencephalographic noise,
readily apparent in Figure 2 of our paper (p 422), in a
recording system with relatively generous high-pass characterisacs.
Rrfwrnces
1 . Rowe MJ: Normal variability of the brain-stem auditory
evoked response in young and old adult subjects. Electmencephalogr Clin NeurophyioI44:4S9-470, 1978
2. S k y A, McKean CM: Postnntal development of human
brniartem p o t e n d s during the first year of life. E l m
encephdop Clin Neurophysiol 40:418-426. 1976
From the Laboratory of Elecuomyography and Applied Clinical
Neurophysiologg, Stanford University Medical Center, Stanford
CA 94305.
BAER
(left ear)
I
11 111
1v-v
v1
v11
From the Lpbonuory of Clinical Neurophysiologg, Mpuochusem
Genelsl Hospitpl, Boston. M A 02 114.
Notes and Letters
585
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