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.