Dropped Head Syndrome associated with Motor Neurone Disease

Original Editor - Eugenie Lamprecht Top Contributors - Eugenie Lamprecht and Kim Jackson  

Introduction

Dropped head syndrome (DHS) is a rare condition characterized by severe weakness of neck extensors and may associate with weakness of shoulder girdle and proximal arm muscles. This occurs as a result of several neurological, neuromuscular, muscular, and other causes.

Neurological conditions that may lead to DHS include;

• • amyotrophic lateral sclerosis (ALS),
  • Parkinson disease
  • multiple system atrophy,
  • cervical dystonia,
  • postpolio syndrome,
  • cervical myelopathy,
  • chronic inflammatory polyneuropathy (CIDP),
  • neuromuscular causes include myasthenia gravis (MG),
  • Lambert-Eaton myasthenia syndrome (LEMS),
  • muscular causes include primary inflammatory such as polymyositis,
  • Scleromyositis,
  • isolated inflammatory axial myopathy,
  • primary non-inflammatory conditions (nemaline myopathy, mitochondrial myopathy, and congenital myopathy)
  • isolated neck extensor myopathy (INEM).

Clinical presentation

The typical clinical presentation of DHS refers to a “chin on chest” posture due to neck extensor muscular weakness. This makes it difficult for individuals diagnosed with DHS to keep their head in an upright position while walking, standing, and talking. Many individuals use their hands to support their chin as a result.

This may also lead to dysphagia, dysarthria, and social implications.

Pathological Process: DHS and Amyotrophic lateral sclerosis

The dropped head syndrome occurs among 1-3% of individuals diagnosed with ALS. Even though this is quite a rare manifestation of ALS but bears a poor prognosis. Dropped Head Syndrome is commonly also associated with bulbar palsy and/ or weakness of the upper limbs.

Research suggests that the development of DHS in ALS may be due to the degeneration of paraspinal anterior horn cells leading to atrophy of affected muscles. It is also progressive of nature and easy to diagnose, as widespread denervation is evident on EMG and mild CK elevation is common.

Difficulty with swallowing, speaking and/ or breathing has also been associated with individuals with DHS and ALS. Individuals may also struggle with neck pain and impairment in ADLs such as dressing, eating, showering, etc.

Diagnostic Procedures

In order to diagnosed dropped head, the healthcare professional should rule out structural causes of the cervical spine first.

It is also important to distinguish between neuromuscular causes and non-neuromuscular causes;

• • NM causes: a significant weakness of neck extensors.
  • Non-NM causes: dystonic anterocollis developing due to an imbalance of neck muscle tone producing neck flexion as a result of repetitive muscle contractions.

Previous medical & family history:

• • Any previous onset or occurrence of isolated/ diffused neck weakness.
  • Any cranial and/ or bulbar muscle involvement.
  • Any respiratory muscle weakness or symptoms.
  • Family and developmental Hx.

Physical examination:

• • Upper and/ or lower motor signs
  • Muscle atrophy
  • Skin changes
  • Ocular or bulbar weakness
  • Facial weakness
  • Selective weakness patterns
  • Pelvic girdle weakness.

Imaging:

• • X-rays to rule out fractures, arthritis and kyphosis.
  • MRI & CT scan to review soft tissue, fatty infiltration, oedema, inflammation and muscle atrophy.
  • Needly study of facial -, tongue -, sternocleidomastoid -, trapezius -, cervical and thoracic spinal muscles.