Dropped head in Parkinson's disease

A propensity to bend the trunk forward and "the chin is now almost immovably bent down upon the sternum" were described by James Parkinson in patients with Parkinson's disease (PD). The term "dropped head" was first reported in "Gerlier disease" in Switzerland and 'kubisagari' in Japan and since then also reported in myositis, myopathy, myasthenia gravis, amyotrophic lateral sclerosis, neuropathy, and hypothyroidism. Disproportionate antecollis occurs in about half cases of multiple system atrophy (MSA) and is considered dystonic in nature. Dropped head is considered rare in PD, both in advanced and early stages of PD. However, it is known to progress subacutely over a period of several days. In my experience, dropped head is relatively common in PD. The mechanism of dropped head in PD is either dystonia of flexor neck muscles or weakness of extensor neck muscles. The response of dropped head to various anti-parkinsonian medications is rather inconsistent. Levodopa is reported to induce amelioration in some patients while dopamine agonists can cause deterioration. Muscle afferent block with lidocaine and ethanol is reported to be effective, while the effect of botulinum toxin injection into the affected muscles is limited. The effect of stereotaxic neurosurgery on dropped head is controversial. Early diagnosis and prompt treatment is necessary to prevent muscle damage associated with long-term overstretch of extensor neck muscles.