Perhaps you should try some spelling variations:
"motor neurone disease" » "motor neuronal disease", "motor neuroe disease", "motor neuronale disease"
"motor neuron disease" » "motor neuro disease", "motor neuronal disease"
"motor neurons disease" » "motor neuros disease", "motor neuronals disease", "motor neuronal disease"
"motor neuros disease" » "motor neuro disease"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("motor neurone disease") or ((((("motor neuron disease") OR ("motor neutron disease"))) or ((("motor neurons disease") or ("motor neuros disease"))))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("motor neurone disease") OR ((((("motor neuron disease") OR ("motor neutron disease"))) OR ((("motor neurons disease") OR ("motor neuros disease")))))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"motor neurone disease\") or (((((\"motor neuron disease\") OR (\"motor neutron disease\"))) or (((\"motor neurons disease\") or (\"motor neuros disease\"))))))".
• Removing quotes may allow a broader search: (( motor neurone disease ) or ((((( motor neuron disease ) OR ( motor neutron disease ))) or ((( motor neurons disease ) or ( motor neuros disease )))))).
• Adding a wildcard symbol may retrieve word variants: (("motor neurone disease") or ((((("motor neuron disease") OR ("motor neutron disease"))) or ((("motor neurons disease") or ("motor neuros disease"))))))*.