doi:10.1136/jnnp.2003.027912
J. Neurol. Neurosurg. Psychiatry 2005;76;143-144
F Nejat, S Zabihyan Sigarchi and M IzadYar
trauma
Congenital dumbbell neuroblastoma mimicking birth

Stiff person syndrome with eye movement abnormality, myasthenia gravis, and thymoma Stiff person syndrome (SPS) is a rare disorder of the central nervous system characterised by progressive fluctuating rigidity and painful spasms of the body musculature. We describe a patient with SPS with positive glutamic acid decarboxylase (GAD) antibodies who developed diplopia. Thymoma was detected by computed tomography (CT), and after thymectomy his symptoms improved. One month after thymectomy, he tested positive for antiacetylcholine receptor (AchR) antibodies.
Case report A 45 year old man presented with a four week history of back pain and stiffness of his trunk causing difficulty in bending forward and turning over while lying down, which he attributed to a minor injury sustained while playing squash. He later developed asymmetrical stiffness of the legs and difficulty walking. His past medical history was notable for an episode of dysphagia (two weeks’ duration) associated with heartburn six months ago; a gastroenterological evaluation and an endoscopy at that time were normal. He recovered spontaneously and there was no recurrence. On examination his mental status, speech, and cranial nerves were normal. He had exaggerated lumbar lordosis. Neurological examination showed normal bulk with increased tone of the flexors and extensors of the knee and ankles. Power and coordination were normal, deep tendon reflexes were
brisk, but he had flexor plantar responses. There was no evidence of fatigable muscle weakness. Sensory examination was normal. A chest radiograph and magnetic resonance imaging (MRI) of the brain and the spinal cord were normal. He was anti-GAD antibody positive at 3.4 U/ml (radioimmunoassay; normal 0–1 U/ml). Full blood count, vitamin B12, folate, thyroid function tests, liver function tests, urea, electrolytes, glucose, cortisol, immunoglobulins, and electrophoresis were normal. Antinuclear antibody and smooth muscle, mitochondrial, parietal cell, gliadin, reticulin, microsomal, thyroid peroxidase and antineutrophil cytoplasmic antibodies were negative. Cerebrospinal fluid (CSF) examination revealed 9 lymphocytes/ mm3. CSF protein and glucose were normal at 0.31 g/l and 3.1 mmol/l, respectively and oligoclonal bands were absent. The spasms were controlled with diazepam, but his symptoms recurred on reducing the dose. A diagnosis of SPS was made. Treatment with intravenous immunoglobulins (400 mg/kg per day for five days) was not beneficial. He later improved on baclofen 20 mg/day and clonazepam 0.5 mg at bedtime.
Four months after the onset of stiffness, he developed diplopia. Visual acuity was 6/4 in both eyes. He had variable alternatingesotropia of up to 10 prism dioptres at distance and esophoria at near. Eye movement examination showed bilateral mild abduction deficit, variability of horizontal and vertical saccades with a tendency to be slow, and slight endpoint nystagmus. There was no ptosis or weakness after sustained upgaze for one minute. Eye movement recordings, obtained with a high resolution video pupil tracker (EyeLink, Sensomotoric Instruments, Berlin, Germany; sample rate 250 Hz) confirmed the clinical findings (fig 1, top panel). Anti-AChR antibodies were negative. The neurological findings were unchanged. Motor and sensory nerve conduction studies and ulnar and radial repetitive nerve stimulation were normal. Concentric needle electromyography (EMG) showed sporadic fasciculation potentials in the tibialis anterior. Single fibre EMG from 34 potential pairs from the orbicularis oculi revealed only one site with definitely abnormal jitter. A chest CT scan revealed a thymic mass. Histological examination confirmed thymoma with minimal involvement of the perithymic fat. His symptoms improved over a month after thymectomy. One year from the onset of symptoms, one month after thymectomy, he tested positive for anti-AChR antibodies (44610210M/l) radioimmunoassay in the same laboratory, normal 0–5610210 M/l) and remained positive for anti-GAD antibodies (2.0 U/ml). His eye movements improved significantly after thymectomy as evidenced by eye movement recordings that showed less variability ofsaccadic velocity (fig 1, bottom panel). Eighteen months after the onset of symptoms he is off medications and back to his normalroutine. He has mild intermittent stiffness of his back, precipitated by anxiety. Occasional mild diplopia at far distance persists.