The question asks which of the given signs are suggestive of Parkinson's disease. Parkinson's disease is a chronic neurodegenerative disorder caused by loss of dopaminergic neurons in the substantia nigra, leading to the cardinal motor features of rigidity, bradykinesia, resting tremor, and postural instability.

Analysis of Each Statement

• 1. Lead pipe rigidity: This is a uniform, continuous resistance felt throughout the range of passive movement of a limb, without the ratchet-like interruptions. It is one of the classic forms of rigidity seen in Parkinson's disease and is correct.
• 2. Cog wheel rigidity: This is a jerky, ratchet-like resistance to passive movement, produced by rigidity superimposed on an underlying tremor. It is a hallmark, highly specific sign of Parkinson's disease and is correct.
• 3. Festinating gait: A characteristic gait abnormality in Parkinson's disease consisting of stooped posture, short shuffling steps, reduced arm swing, and an involuntary tendency to accelerate (festination). This is correct and one of the most recognizable clinical features of the disease.
• 4. Romberg test positive: A positive Romberg sign reflects loss of proprioceptive or vestibular input (e.g., sensory ataxia, posterior column disease, vestibular disorders) rather than an extrapyramidal movement disorder. Parkinson's disease causes postural instability due to loss of postural reflexes, but this is tested clinically by the "pull test," not the Romberg test, and Parkinson's patients are typically Romberg-negative since their proprioceptive pathways are intact. This statement is incorrect.

Conclusion

Lead pipe rigidity, cog wheel rigidity, and festinating gait (statements 1, 2, and 3) are all well-established signs suggestive of Parkinson's disease, while a positive Romberg test (statement 4) is not a feature of Parkinson's disease and instead points toward a sensory or vestibular deficit.

Hence, the correct answer is 1, 2 and 3.