Discussion
Extramedullary hematopoiesis is a rare manifestation of thalassemia that
was first described by Guizetti during an autopsy in 1912 (16). Gatto
was the first to describe spinal cord compression from the
extramedullary overgrowth of the hematopoietic tissue(17).the diagnosis
of the disease depends on symptoms which is confirmed by MRI finding .
the male-to-female ratio for spinal cord compression by extramedullary
mass was 5:1. Thoracic cord compression was seen primarily in the lower
thoracic spine(11). Extramedullary hematopoiesis occurs in multiple
blood disorders including thalassemia. The usual organ involvement
includes the liver, spleen, bone marrow and lymph nodes. The onset of
neurologic symptoms in a patient with such underlying blood dyscrasias
should prompt a high clinical suspicion for cord compression or thecal
sac compression by an extramedullary hematopoietic process. The
treatment modalities available to such patients are limited.
Intervention options have included multiple blood transfusions to
downregulate erythropoietin production, radiation therapy to stop the
production of overgrown marrow tissue, surgical decompression or a
combination of any of the above(11)(18). The relative benefit of one
treatment over another has not been clearly established due to the
infrequency of this disorder. The risks of surgical treatment include
excessive bleeding in a patient with a low hemoglobin and difficulty in
transfusion due to antibodies and cardiopulmonary stress. The benefit of
surgery includes immediate resolution of compression and its symptoms
upon decompression. Surgical decompression also provides a good
histologic diagnosis. Lau et al, report the case of a 28-year-old woman
with cord compression in the thoracic spine who underwent surgical
decompression with immediate postoperative recovery of weakness. A
complete resolution of symptoms had occurred at 2 months follow-up.
Multiple transfusions were also required to maintain the hemoglobin
above 10 g/dl(18).our patient was reviewed by neurosurgery initially but
as mentioned before , surgery was decline and he offered low dose
radiotherapy instate . The risks of radiotherapy in the treatment of
cord compression in such patients include the lack of any tissue for
histological diagnosis and the risks involved with radiation exposure.
The benefits include ready availability, effectiveness in the resolution
of symptoms in a short period of time and reduction of local
recurrence(19). Abassioun and Amir-Jamshidiin 1982 reported the case of
a 15-year-old female who was paraparetic with long tract signs(20). The
patient’s symptoms resolved after 1500 cGy of radiation in five
treatments with only residual right sustained clonus. Kaufman et al also
reported two patients with thalassemia who underwent radiation therapy
with resolution of symptoms in 3–7 days(19). Singhal et al in a review
of the literature argue that radiation therapy should be the primary
modality for treatment, and surgical intervention and transfusion should
be reserved for the recurrent cases post-radiation(21). The radiation
dosage used mostly in different treatment protocols included a range
between 1000 and 3000 cGy. Our patient received 2000 cGy for ten
sessions with good response evident by resolution in his symptoms and
with no complications.