Option A is correct: Left optic tract
Explanation:
1. A positive Hoffmans sign is a sign of upper motor neuron dysfunction and points to a disease of the central nervous system – in this case from the history degenerative cervical myelopathy [DCM] affecting the cervical spinal cord is most likely.
2. To elicit it, the examiner should flick the patient's distal phalanx (usually of the middle finger) to cause momentary flexion.
3. A positive sign is exaggerated flexion of the thumb.
4. DCM is often missed initially and there is a delay in the diagnosis of this condition by >2 years in some studies.
5. This is a problem as delayed treatment limits recovery.
6. It is most commonly misdiagnosed as carpal tunnel syndrome and in one study, 43% of patients who underwent surgery for degenerative cervical myelopathy, had been initially diagnosed with carpal tunnel syndrome.
7. DCM is therefore an important differential in patients suspected to have Carpal Tunnel Syndrome [CTS].
8. CTS is a disease of the peripheral nervous system, resulting from median nerve compression at the wrist inside the carpal tunnel.
9. It therefore affects only the aspects of the hand innervated by the median nerve: Sensation; Thumb / Index / Middle Finger.
10. This typically manifests as intermittent pain or paraesthesiae.
11. Motor; LOAF Muscles (lateral lumbricals, opponens pollicis, abductor pollicis brevis and flexor pollicis brevis).
12. Motor signs are less commonly seen with presentations of CTS, but wasting of the thenar eminence may be present.
13. Tinels test and Phalens test can be positive, but not always.
14. Both tests aim to increase the pressure within the carpal tunnel, to try to exacerbate symptoms; Tinels test via tapping on it and Phalens test by sustained full flexion of the wrist.
15. In focal central nervous system disorders, like DCM, examination features are known to have low sensitivity but high specificity.
16. As a disease of the cervical spinal cord, DCM can affect the sensory, motor and autonomic nervous systems from the neck downwards.
17. Motor signs will be upper motor neuron signs such as increased toned, hyper-reflexia and pyramidal weakness.
18. Note that the neurological signs of DCM are often subtle initially and easily missed, but as a progressive condition they are likely to get worse.
19. Therefore, detecting early DCM can be challenging.
20. A high index of suspicion, alongside a comprehensive neurological examination and monitoring for progression is required.
