An implantable apparatus can comprise an electrical test energy delivery circuit configured to provide an electrical test signal to a cervical location in a patient body. A detector circuit can use the electrical test signal to detect cervical impedance and generate a cervical impedance signal representing fluctuations in the detected cervical impedance. The implantable apparatus can comprise a therapy delivery circuit, such as configured to provide electrical neural modulation therapy using a neural modulation timing parameter, and a processor circuit that can be coupled to the electrical test energy delivery circuit, the detector circuit, and the therapy delivery circuit. The processor circuit can be configured to determine a pulsatile signal or pulse pressure signal, such as using the cervical impedance signal, identify a characteristic of the pulsatile signal or pulse pressure signal, and control a neural modulation therapy using the timing parameter and the identified pulse pressure signal characteristic.