Slowly progressive sensory hemisyndrome: unusual presentation of paraneoplastic sensory neuronopathy

Dear Editor, A 59-year-old woman complained of slowly progressive unsteadiness, gait difficulties, and a left sensory hemisyndrome. She had smoked heavily until 2004. In October 2006, she complained of diffuse muscle pain and fever, and a chest computed tomography (CT) scan was normal. Four months later, right pulmonary arterial thromboembolism was diagnosed at repeat CT scan. Symptoms disappeared after anticoagulants and steroids. In May 2007, she started complaining of progressive sensory loss, pain, and paraesthesias of the left lower limb. A CT scan in August 2007 was normal. Later, sensory loss and paraesthesias involved the left cervico-occipital region, then the left hand and forearm (September 2008) and eventually the right toes (November 2008), while the gait became ataxic. In December 2008, neurological examination showed an ataxic gait with left lower limb incoordination, left limb pseudoathetosis, superficial and deep sensory loss, severe in the left lower limb, with touch allodynia, moderate in the left hand, and mild in the right foot and left occipital region. Deep tendon reflexes were reduced on the left and absent at both ankles. Sensory action potentials were absent on the left and normal or only mildly decreased in amplitude on the right side (Table), with normal motor conduction studies. Somatosensory evoked potentials revealed markedly decreased amplitudes and mild latency prolongation of all left limb waves, with absent left P37 cortical wave, whereas right limb responses were normal, apart from mild prolongation of P37 wave (Table 1). Skin biopsies, performed bilaterally at proximal thigh and distal leg, showed decreased intraepidermal nerve fiber density and sweat gland denervation, consistent