In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Predominantly sensory , though also motor and autonomic , peripheral neuropathy started in her feet , ascended proximally to the mid - thoracic region , and eventually included her distal upper extremities .
### Output Text:
Predominantly sensory , though also motor and autonomic , peripheral neuropathy started in her feet , ascended proximally to the mid - thoracic region , and eventually included her distal upper extremities . 