The patient’s symptoms and clinical course are progressive with new symptoms occurring as additional structures in the nervous system are being affected. This temporal profile and clinical course is most consistent with a mass lesion most likely neoplastic although vascular malformation or focal infection like an abscess would need to be considered.

Pain localizing to the neck is the first symptom suggesting the anatomical location of the lesion. The pain may be from pain sensitive structures in the neck region that are adjacent to the spinal cord or it could be from nerve root irritation.

The patient’s principle findings are weakness and sensory without any findings suggesting supratentorial (cerebral hemispheres) or infratentorial (brainstem and cerebellar)   involvement.

To understand her weakness, one has to decide if the weakness is from an upper motor neuron lesion (from the lateral corticospinal tracts) or lower motor neuron lesion (final common pathway including the anterior horn cell or ventral nerve root) or a combination of both. In her case, she has findings that suggest both upper and lower motor neuron involvement which definitely helps in localization to the spinal cord.

Upper motor neuron findings including hyperreflexia and mild weakness are found in the right upper extremity as well as hyperreflexia at the right knee jerk. This indicates involvement of the right lateral corticospinal tract at or above the C6 level.

The patient has muscle wasting of the intrinsic hand muscles and significant weakness of the muscles innervated by right C8-T1 nerve roots. She also has dense sensory loss of all sensory modalities in the right C8-T1 dermatome distribution so this, along with the motor findings, suggests that there is lesion of the right C8-T1 spinal roots or nerves in addition to the lesion of the lateral corticospinal tract above this level.

But how do we explain the diminished right ankle jerk, profound weakness of the ankle muscles, foot drop, and no Babinski? We can’t with a lesion of the cervical cord. These findings suggest another lesion in the right lower lumbar-sacral spinal cord.

There are also upper motor neuron findings in the left lower extremity but not in the left upper extremity so we would have to postulate a lesion in the upper thoracic cord on the left affecting the lateral corticospinal tract on that side or a lesion lower down in the lumbar-sacral spinal cord affecting the lateral corticospinal tracts. Lesions below L1 typically are not associated with a Babinski so this is less likely.

Now, let’s go back to the sensory findings and see how we can explain them. As noted above, she had loss of all sensory modalities in the right C8-T1 dermatomes suggesting spinal nerve or root involvement. Her other sensory findings included a sensory level on the left at T2-3 (diminished pain and temperature at and below this level) and diminished but not absent vibratory and position sense in the right lower extremity. The sensory level is one or two spinal cord segment levels below the actual anatomical cord lesion because the spinothalamic axons ascend several spinal cord levels prior to crossing so the anatomical lesion accounting for the left T2-3 sensory level would be at the right C8-T1 cord level. The diminished vibratory and position sense in the right lower extremity could be from a spinal nerve root problem but the loss is not dense and pain and other sensory modalities are not affected so it is most likely from a dorsal column lesion which is probably located in the right lower cervical-upper thoracic spinal cord region.