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Motor Neuron Disease

Short summary

71-year-old female developed progressive dysarthria and dysphagia. Her doctor describes her speech difficulty as “Spastic dysarthria with slow and nasal speech" and noticed decreased mobility in the tongue and palate. She underwent multiple investigations and started Rilutek. The differential diagnosis of isolated swallowing and speaking difficulties include: Early motor neuron disease, Cranial neuropathies, Myopathies, Neuromuscular junction disorders and Neurodegenerative movement disorders. Among the expert's recommendations are additional tests and speech and swallowing consultation and training.

Medical Background
Diagnosis: motor neuron disease.
The patient is a 71 year old lady who developed progressive speaking difficulties since June of 2008. More recently, she developed progressive swallowing difficulties as well.
In December of 2008 was seen by Dr. X, neurology specialist in Milan. He describes her speech difficulty as “Spastic dysarthria with slow and nasal speech”. He notices decreased mobility in the tongue and palate with no other neurological signs on exam.
Multiple investigations including blood work, brain MRI and electro diagnostic studies were performed, the results are summarized below.
Rilutek 50 mg twice a day was started on January 22nd 2009.
Previous investigations:
-       Blood work: Complete blood count, chemistry, glucose, CK levels, liver function tests, thyroid function tests, serum protein electrophoresis (SPEP) were all within normal limits. SPEP with immunofixation was performed, but the report is unclear.
-       Brain MRI (1/2008) revealed evidence of cortical cerebral atrophy with possible periventricular white matter changes. There were no other intracranial lesions. The actual MRI images were not available for review.
-       EMG (French) in January 2009: Nerve conduction studies revealed bilateral median neuropathy across the wrists, worse on the left. Ulnar sensory and motor responses were within normal limits on both sides. Tibial nerve motor responses were within normal limits on both sides. F-wave responses of right and left ulnar and tibial nerves were within normal limits. Repetitive nerve stimulation of the left spinal accessory and right facial nerves were within normal limits. Single fiber EMG was normal. Needle EMG study revealed abnormal spontaneous activity in the left orbicularis oris, right FDI and right biceps. It also revealed evidence of chronic denervation in the right and left tibialis anterior. Left FDI and Glossus muscles were normal.
-       Transcranial magnetic stimulation (French) in January 2009: within normal limits.
Past medical and family history is not available.
Social and occupational history is not available.
Current list of medication is not available.
Medical opinion
We assume that at that time of the neurological examination there was no limb muscle atrophy or weakness and that tone and reflexes were within normal limits in all four extremities.
71 year old lady has isolated progressive isolated dysarthria and dysphagia since June of 2008. The available reports show no clinical evidence of any upper or lower motor neuron involvement in the extremities. Limited EMG study did not fulfill the electro-diagnostic El Escorial criteria for a motor neuron disease. With the current available information she does not fulfill the clinical El Escorial criteria for possible, probable, or definite ALS. However, the clinical history is worrisome for very early motor neuron disease.
The differential diagnosis of isolated swallowing and speaking difficulties include, but not limited to:
-       Early motor neuron disease; detailed examination checking for jaw jerk, tone and reflexes would be helpful. Performing a detailed needle EMG study including the thoracic paraspinal and tongue muscles would be also beneficial. EMG should be repeated every 6 months or sooner if weakness or spasticity develops in the limb muscles.
-       Cranial neuropathies; MRI with concentration on the base of skull and the nasopharyngeal area, serum ACE levels, and a lumbar puncture would be reasonable.
-       Myopathies; less likely since CK levels are normal and there is no limb weakness. Certain muscular dystrophies, such as oculopharygeal muscular dystrophy has been described in Italian families and can cause weakness limited to the nasopharyngeal muscles and eyelids.
-       Neuromuscular junction disorders; although single fiber EMG is normal, checking anti Ach receptor and anti MuSK antibodies would be reasonable.
-       Neurodegenerative movement disorders such as progressive supranuclear palsy; less likely in the absence of other typical findings on exam.
1- Repeat detailed EMG study of bulbar muscles, limb muscles. It is important to also check thoracic paraspinal muscles and tongue muscles.
2- Brain MRI with and without gadolinium with focus on the base of the skull and the nasopharyngeal area.
3- Consider lumber puncture if EMG does not show more widespread motor neuron abnormalities.
4- Additional blood work: Vitamin B12, Folate, PTH, Copper, ACE levels, Anti Ach receptor antibodies, and anti MuSK antibodies.
5- Continue Riluzole 50 mg bid for now assuming early ALS, continue checking liver function tests every month for 3 months and then every three months. Consider stopping Riluzole if a diagnosis other than ALS has been confirmed.
6- Pulmonary function tests.
7- Baruim swallow study.
8- Speech and swallowing consultation and training to prevent aspiration.
9- Monitor and maintain weight.