| Discussion: Differenital: Nerve
Tumor (Neuroblastoma, ganglioneuroma,
etc.) Lympadenopathy Extramedullary
Hematopoesis
Opsoclonus
myoclonus
is a rare neurological disorder characterized by unsteady gait,
intention tremor (rhythmic, involuntary motions of the limbs during
voluntary movements), myoclonus (brief, shock-like muscle spasms), and
opsoclonus (irregular, rapid, horizontal and vertical eye movements).
Other symptoms may include dysphasia (difficulty speaking), dysarthria
(poorly articulated speech), mutism (inability to speak), hypotonia
(decreased muscle tone), lethargy, irritability, or malaise (a vague
feeling of bodily discomfort). Opsoclonus myoclonus may occur in
association with tumors or viral infections. A full oncologic
evaluation should be undertaken in all children with OMA because the
paraneoplastic syndrome may precede the appearance of a systemic
neoplasm.
The minimum
requirements for staging include:
Bilateral iliac crest bone marrow aspirate and biopsy; core biopsies
must contain at least 1 cm of marrow, excluding cartilage, to be
considered adequate Bone radiographs and either technetium
radionuclide scan or MIBG scan Abdominal imaging by CT or MRI scan with
three-dimensional tumor measurements
Chest radiograph (anteroposterior [AP] and lateral); chest CT or MRI
are necessary only if the chest radiograph is positive or if abdominal
mass or lymph node disease extend into the chest Head CT is not necessary unless clinically
indicated
MIBG
is a chemical analog of norepinephrine that is selectively
concentrated in sympathetic nervous tissues such as neuroblastoma. It
can be labeled with radioactive iodine
and imaged by scintigraphy. The MIBG scan is both sensitive and
specific for neuroblastoma, and is recommended at diagnosis and repeat
evaluations of the tumor. Because radioactive iodine is used, the
thyroid gland must be protected by the simultaneous administration of
non-radioactive iodine (eg, potassium iodide). Despite prophylaxis,
thyroid dysfunction becomes a potential complication in up to 64
percent of patients. The addition of thyroxine and methimazole
to potassium iodide, and continuation of thyroid protection for four
weeks after the last dose of radiolabeled MIBG, may be more effective
in preventing thyroid dysfunction. |