LAUSR

Recently, increased attention has been given to polyneuropathy in Parkinson’s disease (PD), with a possible causative role of levodopa (L-dopa) metabolic pathway [1, 2]. Oral L-dopa was mostly associated with a large predominance of slowly progressive mild or subclinical peripheral neuropathy (PNP), whereas levodopa/carbidopa intestinal gel (LCIG) showed an acute or subacute onset in one-third of cases. Moreover, the vast majority of PNP under L-dopa treatment in PD patients showed predominantly sensory axonal impairment. We here report a parkinsonian patient who receivedmoderate dosage of oral L-dopa but developed acute severe predominantly motor axonal PNP. Cerebrospinal fluid (CSF) examination exhibited increased protein content with normal cell counts and was originally considered Guillain-Barré syndrome (GBS). Immuno-modulatory therapy with intravenous immunoglobulins (IVIg) was given but did not improve motor symptoms. This patient was a 65-year-old lady with a 4-year history of rigidity-dominant PD with mild motor fluctuations and occasional freezing. Daily oral dopaminergic medication consisted of 300 mg levodopa in combination with 0.75 mg pramipexole. When waking up in one morning, the patient suddenly developed weakness in her limbs and could not stand up. She was initially hospitalized at a local hospital and considered motor complications associated with PD. Adjusted dopaminergic medication was given but invalid whereas weakness of both legs was progressive. After enrolled in our hospital, neuronal physical examination revealed paresis of the upper extremities (British Medical Research Council (BMRC) scale grade 4/5) and severe flaccid paralysis of the lower extremities (BMRC scale grade 0/5) with absent reflexes in both legs, whereas sensitivity (touch, vibration, pain, and temperature) and deep tendon reflexes did not show abnormalities. Additionally, cranial nerves and higher cortical functions were normal. Magnetic resonance scans of the brain and whole spinal cord showed no obvious abnormalities. Needle electromyographic examination showed reduced compound muscle action potential (CMAP) amplitudes with normal motor conduction velocities (MCVs), whereas sensory action potential (SAP) amplitudes and sensory conduction velocities (SCVs) were normal (Table 1). Biochemical tests demonstrated vitamin B12 365 pmol/L (138–658), folate 7.9 μmol/L (7–46.4), and homocysteine (Hcy) 7 μmol/L (5– 15 μmol/L). Lumbar puncture showed an albuminocytological dissociation with elevated protein levels (1200 mg/L). Anti-ganglioside antibodies, autoimmune disease–related antibodies, and paraneoplastic syndrome– related antibodies were all negative. A provisional diagnosis of GBS was made and the patient was treated with IVIg (25 g per day for 5 days), and with vitamin B12, B1, and folate supplementation. All treatments did not improve motor symptoms. During the following 6 months, motor symptoms recovered minimally. Except for one study [3] and a case series [4] showing subacute onset cases of PNP associated with oral L-dopa treatment, the majority of cases of PNP associated with oral Ldopa showed a chronic onset, with slowly progressive axonal impairment selectively involving the sensory fibers. Interestingly, our present case firstly presented the clinical profile that acute motor axonal PNP occurred in one parkinsonian patient receiving moderate dosage of oral L-dopa. Indeed, even in the LCIG-treated patients, predominant motor axonal impairment has not been reported, whereas the great majority of PNP under LCIG treatment were generally a sensorimotor PNP with subacute or chronic onsets. Although some studies have shown that high dosage and long duration of L-dopa could increase risk of PNP [2], our Zhou Ou and Liujun Xue contributed equally to this work.