The stiff limb syndrome--a new case and a literature review.

Abstract

Sirs: The stiff limb syndrome is a rare chronic movement disorder that involves one of the extremities. Symptoms include muscle stiffness and painful reflex spasms triggered by acoustic or tactile stimulation. It is characterized by continuous motor unit activity as well as abnormal exteroceptive reflexes in the EMG [1, 3, 6]. It has been suggested that the stiff limb syndrome differs from the stiff man syndrome in its clinical expression, laboratory findings and treatment response; however, the current diagnostic criteria and the clinical management have not been fully evaluated as only limited data are available [4, 8, 9]. Here, we report the case of a 69 year old woman with clinical, electrophysiological and laboratory findings consistent with a stiff limb syndrome of the right leg. Glutamic acid decarboxylase antibodies (GAD-Ab) levels were elevated in serum and cerebrospinal fluid (CSF). Both stiffness and spasms responded to intravenous and oral diazepam. In addition, we also summarized the published reports to date of stiff limb cases. The 69 year old woman had a five year history of progressive stiffness and rigidity involving her right leg. Initially she noted difficulty in walking due to slowing of the movements of the right leg on uneven surfaces. Climbing stairs became impossible in due course. The right ankle was also affected, leading to the foot being held in an abnormally plantar flexed and inverted posture. Walking was only possible on the ball of the right foot. She developed intermittent and painful spasms to sudden auditory or tactile stimuli as well as to emotional upset. Furthermore, she experienced action-induced spasms during walking that led to progressive gait instability. The stiffness deteriorated for the first 3 years but then stabilized. Two years after onset of the symptoms the patient underwent a spinal disc operation at the L4/5 level that did not affect the progression of the stiffness. Her past medical and family history were unremarkable, as was a review of systems. On neurological examination there was abnormal posturing of the distal right leg. The right foot was plantar flexed and inverted with hyperextension of the toes. Furthermore the right knee was held fixed in extension. She had a wide based gait with a shortened stride length and circumduction of the right leg. Onset of the stance phase was performed with the right forefoot. Standing on her right heel was not possible. Tendon reflexes were symmetrically normal and the plantar responses were flexor. The rest of the neurological examination was unremarkable with no clinical evidence of extrapyramidal or brain-stem dysfunction. No sensory abnormalities, motor deficits, or cognitive deficits were observed. Laboratory findings: The routine laboratory tests showed normal hematological and biochemical findings, normal blood glucose levels, HbA1c, protein electrophoresis, treponemal serology, vitamin B12 and folic acid levels. The immunological profile showed elevated serum levels for GAD-Ab (204.400 mU/ml; normal values < 70 mU/ml), whereas tests for anti-amphiphysin-, anti-islet cell-, thyroid microsomal-, thyreoglobulin, TSHreceptor-, gastric parietal cell-, smooth muscle cell-, acetylcholinreceptor-, anti-nuclear(ANA, ANCA), anti-Hu-, Yo-, Ri-autoantibodies were negative. GAD-Ab could be qualitatively detected in the CSF. Protein, immunoglobulin level, cell count including histology and microbiological study were within normal ranges. No oligoclonal bands were detected in the CSF. Electrophysiology: The needle EMG performed in the M. vastus lateralis, M. tibialis anterior and ischiocrural muscles showed continuous motor unit activity (CMUA) in the affected limb. Synchronized potentials were absent. There were no signs of neuromyotonia or dystonia. Myography of the paravertebral muscles from the spinal levels T12 to L2 revealed normal findings. Motor and sensory nerve conduction velocities were normal. Central and peripheral motor conduction times (MEPs) in all limbs, as well as limb somato-sensory evoked potentials (SSEPs) were within the normal range. EEG showed no abnormal findings. MRI of the brain and the entire spinal cord was normal. The patient was treated with clonazepam (5 mg over 6 days; p. o.) and intravenous cortisone (prednisolone, 1.000 mg over 5 days) which had no effect on the stiffness. A sustained effect was observed after intravenous and oral application of diazepam (5 mg/d) with a marked improvement of mobility and partial relief of the spasms. The described gait disorder associated with stiffness of the right leg and painful spasm to sudden auditory or tactile stimuli is consistent with a stiff limb syndrome [3, 4, 8]. Corresponding to the clinical LETTER TO THE EDITORS