The regulation of serum sodium after replacing carbamazepine with oxcarbazepine.

PURPOSE: To evaluate changes in serum electrolyte balance and underlying regulatory mechanisms in 10 male patients with epilepsy 2 and 6 months after replacing long-term carbamazepine (CBZ) monotherapy with oxcarbazepine (OCBZ) monotherapy. Arginine vasopressin (AVP) is thought to be most important underlying mechanism of CBZ-related hyponatremia via direct or kidney tubular mechanisms. Furthermore, AVP is as well hormonally regulated by the renin-angiotensin-aldosterone system and atrial natriuretic peptide (ANP). METHODS: The medication of the patients was changed from CBZ to OCBZ. Serum electrolytes, creatinine, albumin, aldosterone, and the N-terminal fragment of ANP (NT-proANP) concentrations were measured before and 2 and 6 months after the change in the medication. RESULTS: The mean serum sodium level diminished after the medication was changed. Serum sodium levels decreased below the reference range in two (20%) patients during OCBZ medication. Serum sodium levels decreased altogether in four patients, and remained unaltered in six patients. Serum aldosterone levels increased in the six patients whose serum sodium concentrations did not decrease, but no increase was found in the patients with decreased sodium levels during OCBZ medication. Serum NT-proANP levels decreased in all patients. CONCLUSIONS: Serum sodium levels decrease after replacing CBZ with OCBZ. The low serum NT-proANP concentrations appear to reflect the decreased serum sodium levels, but a compensatory aldosterone response may prevent the development of hyponatremia in some patients during OCBZ medication.

Motor nervous pathway function is impaired after treatment of childhood acute lymphoblastic leukemia: a study with motor evoked potentials.

BACKGROUND: The objective was to evaluate whether motor nervous pathways are affected when patients are treated for childhood acute lymphoblastic leukemia (ALL). PROCEDURE: Thirty-two children with ALL were studied at the end of treatment by means of motor evoked potentials (MEPs) elicited by magnetic stimulation (MS) transcranially and peripherally and underwent a detailed neurological examination. Thirty-two healthy children matched with them for age, sex, and height served as a control group. RESULTS: The latencies of the MEPs were significantly prolonged along the entire motor nervous pathway in the patients with ALL compared with the healthy controls, indicating demyelination in the thick motor fibres. The MEP amplitudes of the distal extremities elicited by stimulation at the brachial plexus and LV spinal level were significantly lowered in the patients treated for ALL, also indicating anatomical or functional loss of descending motor fibres and/or muscle fibres. The MEP amplitudes elicited by cortical MS showed wider variation and no clear abnormalities were found. Neurological signs and symptoms were common after treatment: 41% of the patients had depressed deep tendon reflexes, 31% had fine motor difficulties and 63% gross motor difficulties, and 34% had dysdiadochokinesia. The conduction delay within the peripheral nerve was related to the post-therapeutic interval after administration of vincristine and the lesions within the CNS to the number of injections of intrathecal methotrexate. CONCLUSIONS: The present results show adverse effects of the ALL treatment on the entire motor nervous pathways. In our experience, the measurement of MEPs by MS provides an objective, painless, and practical tool for assessing the treatment-related neurotoxicity in both the CNS and the peripheral nerves. These disturbances in the motor nervous pathways at the end of treatment raise the question of the long-term effects of ALL treatment on the motor nerve tracts, and have led us to employ MEPs to study these effects in long-term survivors of ALL.