A patient with Beta thalassaemia major presenting with cauda equine syndrome due to extramedullary haematopoiesis

Beta-thalassaemia major is a hereditary haematological disorder characterized by anomalies in the synthesis of the beta chains of hemoglobin resulting in anaemia requiring repeated blood transfusions. Inadequately transfused patients commonly present with growth retardation, hepatosplenomegaly, leg ulcers and skeletal changes resulting from expansion of the bone marrow. Cauda equina syndrome or spinal cord compression by extramedullary haematopoiesis has also rarely been reported due to development of masses. 
We report a case of 16 year old female with beta-thalassaemia major who presented with bilateral lower limb paralysis secondary to cauda equina syndrome with extra medullary haematopoiesis.


Introduction
Beta thalassaemia major is an autosomal recessive haemoglobinopathy in which there is minimal to no beta globin chain synthesis, leading to profound transfusion-dependent anaemia [1]. Extramedullary haematopoiesis in thalassemia is usually secondary to undertreated severe anaemia.
Extramedullary haematopoiesis can occur in any organ that participates in haematopoiesis during fetal development. Paraspinal involvement leading to cauda equina syndrome has been reported in a few case reports [2].

Case presentation
A 16-year-old female with beta thalassaemia major on monthly blood transfusions with a history of splenectomy at the age of six years, was admitted with insidious onset bilateral lower limb weakness for seven days, worsening over three days. On admission, she was unable to walk even with support. There was no upper limb involvement. She had concomitant urinary retention with faecal incontinence. There was no history of a fall or trauma to the back.
On examination, she was moderately pale and had mild hepatomegaly. Neurological examination revealed bilateral asymmetrical lower limb flaccid paraparesis with right side being more affected (right side power 2/5, left side power 3/5). Both ankle and knee jerks were absent, bilaterally. The plantar reflexes were flexor. There was sensory impairment for both fine touch and pain in the lumbar (L)5 and sacral (S)1-3 areas in both limbs with right side being more affected. Proprioception was intact. Saddle anaesthesia (L5-S2) was noted with reduced anal tone. Upper limb examination was and there was no spinal tenderness. A diagnosis of cauda equina syndrome was made and she was started on intravenous (IV) dexamethasone 8mg 8 hourly.
The full blood count revealed a hypochromic microcytic anaemia (haemoglobin-6.2 g/dl). Inflammatory markers were normal. Urgent magnetic resonance imaging (MRI) of the lumbar sacral region was arranged which revealed an extradural lesion causing cauda equina compression at L2/ L3 levels most likely due to extramedullary haematopoeisis [ Figure 1]. Urgent laminectomy and spinal canal decompression was performed by the neurosurgical team. She was discharged three weeks after the surgery and was able to walk with support by then. With continued physiotherapy she was able to walk independently eight weeks after surgery.

Discussion
Extramedullary haematopoiesis is a well-recognized complication of conditions with ineffective haematopoiesis which results in production of blood elements outside the bone marrow.
Paraspinal involvement manifests with debilitating clinical consequences secondary to nerve compression. Various clinical presentations have been reported including back pain, paraesthesia, paraplegia and bladder and bowel involvement [3]. Early diagnosis of paraspinal involvement is important in reducing irreversible neurologic damage that may occur with prolonged undiagnosed cord compression. Currently, MRI is considered the method of choice for diagnosis [3].
According to published data, both transfusion and hydroxyurea therapy have a role in the prevention and management of paraspinal involvement with extramedullary haematopoiesis [4]. Surgical decompression also plays a role depending on the clinical severity [5].
A tentative diagnosis of cauda equina syndrome was made in our patient on admission and she was started on steroids in view of reducing the extent of permanent nerve damage. She was referred to the neurosurgical unit after confirming the diagnosis with MRI and laminectomy was performed which resulted in a dramatic response. This case highlights the importance of early diagnosis and treatment of paraspinal involvement due to extramedullary haematopoiesis in patients with beta thalassaemia.