Ascending sensory motor polyradiculoneuropathy with cranial nerve involvement following administration of intrathecal methotrexate and intravenous cytarabine in a patient with acute myelogenous leukemia: a case report*

Anterior lumbosacral polyradiculoneuropathy following intrathecal methotrexate administration: a case report and literature update

INTRODUCTION

We describe a case of intrathecal methotrexate toxicity and perform a literature review of existing cases.

CASE PRESENTATION

A 23-year-old man who received diagnosis of acute lymphoblastic leukemia and started chemotherapy according to the LAL1913 protocol underwent CNS prophylaxis with intrathecal methotrexate. About 1 month after, he developed a flaccid paraparesis. CSF analysis showed albumin/cytological dissociation. Spinal MRI showed thickening of the ventral roots of the cauda equina with contrast enhancement. Nerve conduction studies showed severe lower limb motor axonal neuropathy. Needle examination showed acute denervation involving L3-S1 roots. Methotrexate was stopped, and the patient was treated with intravenous immunoglobulins, followed by high-dose intravenous methylprednisolone, with a gradual improvement. Three months later, the spine MRI was normal. Electrophysiological and imaging findings were indicative of pure motor L3-S1 polyradiculopathy.

DISCUSSION

Literature review of existing cases confirm the relatively selective involvement of lumbosacral ventral roots in intrathecal methotrexate toxicity. Pathophysiologic mechanisms suggest either a direct toxicity with localized folate deficiency or an immune-mediated mechanism, the latter consistent, in our patient, with the albumin/cytological dissociation and response to immunomodulatory treatments. Pure motor polyradiculopathy of the lower limbs is rare but predictable complication of intrathecal methotrexate, which can benefit from early withdrawal and immunomodulatory treatments.

Acute myeloid leucaemia presenting as a rapidly progressive polyradiculoneuropathy

Neurological involvement at onset in acute myeloid leucaemia (AML) is rare, with only a few isolated case reports. We present the case of a 46-year-old man with rapidly progressive polyradiculoneuropathy as the presenting feature of AML. The proposed mechanism for this is postulated to be direct intraneural infiltration, although a paraneoplastic, autoimmune-related phenomenon could be possible. Despite chemotherapeutic intervention, the patient died 1 month after initial presentation. Although rare, neurological manifestations of AML do occur and it is important to include haematological malignancies in the differential diagnosis in patients presenting with neurological symptoms.