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1098

12. Tolge CF, Factor S. Focal dystonia secondary to cerebral toxoplasmosis in a patient with AIDS. Mov Disord 1991;6:69-72.
13. Metzer WS. Movement disorders with AIDS encephalopathy: case
report. Neurology 1987;37:1438.
14. Lee MS, Marsden CD. Movement disorders following lesions of
the thalamus or subthalamic region. Mov Disord 1994;9:493-507.
15. Mooro Y, Hirayama K, Kojima S. Involuntary movements caused
by thalamic lesion. Rinsho Shinkeigaku 1994;34:804-811.
16. Lee MS, Lee SA, Heo JK, Chor IS. A patient with resting tremor
and a lacunar infarction at the border between the thalamus and the
internal capsule. Mnv Disord 1993;8:244-246.
17. Chika J, Bogousslavsky J, Henderson J, et al. The "jerky dystonic
unsteady hand": a delayed motor syndrome in posterior thalamic
infarctions. J Neurol 1994;241:537-542.
18. Miwa H, Hatori K, Kondo T, Imai H, Mizuno Y. Thalamic tremor:
case reports and implications of the tremor-generating mechanism.
Neurology 1996;46:75-79.
19. Navia BA, Petito CK, Gold JWM, et al. Cerebral toxoplasmosis
complicating the acquired immune deficiency syndrome: clinical
and neuropathological findings in 27 patients. Ann Neurol 1986;
19:224-238.

Delayed Onset Postural Tremor Caused by
Parietal Lesion

Postural tremor stemming from a focal brain lesion was
originally described by Benedikt (1) and Holmes (2) as being
caused by a lesion of the midbrain and was recently reported as
being associated with lesions of the thalamus (3-5). In this

A videotape accompanies this article.
Received February 8, 1996; revision received June 25, 1996. Accepted January, 1997.
Address correspondence and reprint requests to Dr. I. Moroo at
BiotechnologyLaboratory, Room 237, Wesbrook Building, University
of British Columbia, 6 174 University Boulevard, Vancouver, BC, V6T
123 Canada.

brachii
b 'ceps

report, we describe a patient suffering from tremor of the same
character, but after a lesion in the parietal lobe.

Case Report
A 56-year-old right-handed man was referred to our hospital
for tremor in his right arm. At age 43 (13 years prior to this
referral), he had developed sudden right-sided hemiparesis and
sensory disturbances associated with paraphasia and alexia.
Within several days, his ability to speak and read had improved, but his motor and sensory disturbances continued for
months. Six months after the onset of his stroke, when his
hemiparesis had improved, he first noticed tremor in his right
arm. For the 13 years between its appearance and his referral,
the tremor neither worsened nor improved. On examination, he
was fully oriented and had neither aphasia nor alexia. His muscular tone and strength of his right arm and leg were normal.
The tendon reflexes were generally diminished, with no plantar
responses. He had diminished senses of touch, pain, and vibration on his right side, prominently at the distal ends of his limbs
but sparing the medial part of his face.
Discriminative senses of position and weight were impaired
in his right arm. The tremor was characterized as follows: when
lifting his right arm to the horizontal, particularly when his
elbow joint was flexed, his forearm moved up and down around
his elbow joints. No involuntary movements were observed
when his arm was at rest. Surface electromyography recorded
from the muscles of the upper right limb showed regular grouping discharge at a rate of 5 Hz (Fig. 1). Magnetic resonance
imaging showed a circumscribed lesion in the white matter of
the left inferior parietal lobule (Fig. 2). No thalamic, brainstem,
or cerebellar lesion was identified. Signal intensity was low in
the T1-weighed image and high in the T2-weighed image,
which was compatible with infarction. Somatosensory evoked
potentials following median nerve stimulation showed disappearance of late cortical components after right stimulation
(Fig. 3).

Discussion
This patient had postural tremor and disturbances of discriminative senses that were most likely caused by a parietal

~~~~

FIG. 1. Surface electromyograph recorded at right biceps brachii, triceps
brachii, flexor carpi ulnarlis, and extensor carpi radialis shows reciprocal discharges between extensor and flexor
muscle groups.

Movement Disorders, Vol. 12, No. 4 1997

CLINICAUSCIENTIFIC NOTES

I099

proposed that thalamocortical fibers are one of the neural structures maintaining the rhythmic thalamic discharges. The absence of late cortical components on the affected site, in spite
of the presence of preserved early cortical components, suggests that the sensory system was disturbed after reaching the
potentials of the primary sensory cortex. Magnetic resonance
imaging shows the subcortical white matter of the inferior parietal lobule located in the associated sensory area.
The clinical feature of sensory disturbance, the abnormality
of the somatosensory evoked potentials, and the magnetic resonance imaging findings all suggest that this case primarily involves the associated sensory area. We suspect that the parietal
subcortical lesion influences the neural circuit of the tremor,
thereby inducing the thalamus to generate rhythmicity. In this
way, the disturbance of thalamocortical fibers could elicit a
postural tremor similar to that from a thalamic lesion. We also
think that the time gap between the onset of stroke and the
occurrence of tremor reveals that the tremor is not the symptom
of a simple defect of neuronal circuitry, but the result of secondary repairing of the nervous system, for example, sprouting.

Legend to the Videotape
FIG. 2. Axial T2-weighted magnetic resonance image (TR = 2,080,
TE = 80) at the level of centrum semiovale, showing increased signal
intensity at the left inferior parietal lobule (arrowhead) compatible with
infarction extending to white matter.

lobe infarction. It is noteworthy that there was a delay between
the stroke and the onset of tremor, because this delay is also
seen in cases of tremor caused by rubral or thalamic lesions.
Such tremor is very rare among patients with a focal parietal
lesion. In 1982, Andrews et al. (6) reported delayed-onset
tremor of a similar character following infarction in the white
matter of the parietal lobe, but did not refer to sensory disturbances accompanied by parietal lesion. According to the presumed mechanism that lesions involving the dentatorubrothalamic pathway induce tremor, it is difficult to explain the relationship between the tremor and the lesion. Ohye (7)

When the patient stretches his arm to the front of his body,
a flexion-extension movement emerges at the wrist joint of his
right hand. The tremor does not appear during action and goaldirected movements, but does emerge when the patient reaches
his finger to his nose. The tremor is characterized by flexionextension movement of the forearm and is most prominent
when the patient puts his forefingers close together in front of
his face.

Iku Moroo
Keizo Hirayama
Masashi Nakajima
Department of Neurology
School o j Medicine
Chiba University
Chiba, Japan

C’3 - A1 +A2
If. sum.

c5

C’3 - A1 +A2

C6

rt. stlrn.

c7

C’4 - A I + A 2
It. stim.

C8

c‘4 - A 1 +A?
r t stlm.

50msec

FIG. 3. Alternative stimulation of bilateral median
nerves’ somatosensory evoked potentials recorded at
C’3 and C’4. Right stimulation shows a small delay of
N19 (20.0 ms) compared with left stimulation (18.6 ms).
N33 was clearly identified at C’4 by left stimulation, but
by right stimulation N33 failed to form a clear peak at
C’3 (urrowhead). P40 and N60 were absent on the left
cortex by right stimulation, whereas an apparent wave
was detected on the right cortex by left stimulation.

1 OOmsec

Movement Disorders, Vul. 12, No. 6, 1997

CLINICAUSCIENTIFIC NOTES

1100

References
1. Benedikt M. Tremblement avec palalyie croisee du moteur oculaire commun. Bull Med 1889;3:.547-548.
2. Holmes G. On certain tremors in organic cerebral lesions. Brain

1904;27:327-375.
3. Kim JS. Delayed onset hand tremor caused by cerebral infarction.
Stroke 1992;23:292-294.
4. Mossuto-Agatiello L, Puccetti G, Castellano AE. “Rubral” tremor
after thalamic haemorrhage. J Neurol 1993;241:27-30.
5. Miwa H, Hatori K, Kondo T, Imai H, Mizuno Y. Thalamic tremor:
case reports and implications of the tremor-generating mechanism.
Neurology 1996;46:15-79.
6. Andrews J, Fowler CJ, Harrison MJG, Kendall BE. Post-traumatic
tremor due to vascular injury and its treatment by stereotactic
thalamotomy. J Neurol Neurosurg Psychiatry 1982;45:560-562.
7. Ohye C. Neurons of thalamic ventralis intermedius nucleus: their
special reference to tremor [in Japanese]. Shinkei Kenkyu N o
Shinpo 198.5;29:222-23 1.

Sustained Effect of High-Dose Intrathecal Baclofen
in Primary Generalized Dystonia: A 2-Year
Follow-Up Study

Baclofen is a muscle relaxant and antispastic agent with selective agonist action on GABA-B receptors. In dystonia its
mechanism of action remains speculative: At the central level,
enhanced GABAergic output from the putamen may cause
thalamocortical inhibition, and at the spinal level GABAergic
receptor binding may decrease the release of neuroexcitatory
transmitters (1,2). Despite these uncertainties, it has been used
orally in the treatment of generalized dystonia, with a favorable
response in up to 30% of the patients (1). However, marked
sedation often precludes the use of therapeutic dosages. Intrathecal delivery of baclofen via an implanted pump (IT-B) could
be an alternative because it achieves higher cerebrospinal fluid
concentrations and diminishes systemic side effects (3,4). Earlier case reports on its use in dystonic syndromes of mixed
origin have given conflicting results. Many issues concerning
the method of the intrathecal loading trial, adequate maintenance dosage, and the long-term effect remain unresolved (2,
5-9).

Case History
A 32-year-old man had developed focal dystonia of the left
arm, appearing at age 13. Birth history and early developmental
milestones had been normal; prior exposure to neuroleptics was
absent. He later developed oromandibular dystonia. At the age
of 18, dystonia spread to the lower extremities. At the age of

A videotape accompanies this article.
Received June 19, 1996; revisions received February 2.5 and April
15, 1997. Accepted May 8, 1997.
Address correspondence and reprint requests to Dr. N. J. Diederich,
Department of Neurosciences, Centre Hospitalier de Luxembourg, 4,
rue Barblt, L-1210 Luxembourg.

Muvemenr Disorders, Vul. 12, Nu. 6, I997

25, the patient presented to our clinics, disabled by generalized
dystonia with features of spasmodic adductor dysphonia, oromandibular and pharyngeal dystonia, intermittent opisthotonus,
marked lordotic arching of the trunk, and dystonic movements
of all limbs, worse on the left. He could not lie on his back and
was mostly wheelchair-bound. Dystonic spasms produced severe muscular pains. His dysphagia and persistent muscle activity left him cachectic. Parkinsonian or spastic features were
absent, and the patient denied diurnal fluctuation of his symptoms.
His family history was remarkable for a 25-year-old sister
with moderate retrocollis and an 8-year-old nephew with mild
lordosis. Laboratory evaluations showed mild iron deficiency
anemia and normal values for thyroid, folic acid, B 12, cemloplasmin, prealbumin, retinol binding protein, VDRL, and porphyrins. Peripheral smear for acanthocytosis was negative. Results of cerebrospinal fluid (CSF) testing were normal. Duodenal biopsy, electroencephalography, computed axial
tomography with contrast, and psychometric tests also produced nonnal results.
Medical treatment with benzodiazepines at the age of 13
produced a transient amelioration. The addition of trihexyphenidyl 30 mg/day at the age of 18 was without benefit. The
patient failed to show sustained benefit from polytherapy over
the next 7 years, including different combinations of trihexyphenidyl (up to 50 mglday), diazepam (up to 30 mglday), oxazepam (up to 15 mglday), haldoperidol (up to 4 mg), and
levomepromazin (up to 50 mg/day). Oral baclofen was given
without sufficient effect up to a dosage of 150 mglday, at which
the patient suffered intolerable and dose-limiting tiredness.
After obtaining oral informed consent, an IT-B test infusion
was initiated. IT-B loading dose infusion of 42 yg/h was given
continuously during 24 h by an external micropump. Under
close supervision, the patient demonstrated a dramatic relief of
his dystonic movements at all levels within 12 h. Response was
complicated by marked but transient periods of somnolence,
without autonomic dysfunction. Upon completion of the infusion challenge, the patient was discharged to home. His dystonic symptoms returned to baseline. One year later, a programmable subcutaneous infusion pump (SynchroMed pump;
Medtronic, Minneapolis, MN, U.S.A.) and intrathecal lumbar
catheter were implanted for long-term continuous infusion after
written informed consent had been given by the patient. The
dystonic condition worsened during the immediate postoperative phase, causing suture disruption and dislodgement of the
catheter. Other acute complications included temporary catheter disconnection and leak of sterile CSF in the tissue. After
catheter revision and vancomycin treatment, baclofen infusion
was reinstituted, beginning at 150 pglday and increased to 900
yglday over a IS-month period. Oral trihexyphenidyl was substantially reduced, and the type of benzodiazepine was exchanged (see Table 1).
The patient was followed as an outpatient with the baclofen
pump for 23 months without further side effects or complications. Because of the marked benefit, the patient refused to
reduce the IT-B dose. Although the IT-B improved the axial
dystonia, cervical dystonia remained unchanged. Therefore, the
patient received injections of botulinum toxin into cervical
muscles. Five videotape segments were obtained before and
during IT-B treatment: The first two clips had been recorded 13
and 4 months before the pump installation and the three others