Final answer:
The absence of Hoffmann's reflex cannot definitively rule out cervical spondylotic myelopathy (CSM); it's a false statement. Other findings like the Babinski sign and clasp-knife response should be considered for a complete assessment.
Step-by-step explanation:
The statement 'Hoffman's reflex = significant if present; absence means that you can confidently rule out CSM' is false. Hoffmann's reflex, a neurological exam finding, is of a finger flicking movement that may indicate an upper motor neuron (UMN) lesion, such as cervical spondylotic myelopathy (CSM). However, its absence does not definitively rule out CSM. In a neurological exam, the absence of this sign must be interpreted within the context of other clinical findings.
The presence of a positive Hoffmann's reflex suggests UMN disease but must be corroborated with other signs such as the Babinski sign, check reflex, and clasp-knife response, which are also indicators of UMN lesions. For instance, the clasp-knife response is characterized by resistance in muscle movement that suddenly gives way, similar to the mechanism of a pocketknife closing. The Babinski sign involves the dorsiflexion of the foot and extension and splaying of the toes in response to plantar reflex which is controlled by corticospinal input, and is indicative of UMN disease when it persists beyond early childhood.