Coat Hanger Pain
"Coat-hanger pain", also known as "coat-hanger ache," has two meanings. It can refer to a topographical distribution of pain and a distinct clinical syndrome related to orthostatic hypotension (OH). The name comes from the area of involvement following the outline of a coat hanger when looking posteriorly - the neck and bilateral trapezius regions.
Anatomy
The coat hanger region describes the anatomical area encompassing the posterior neck, upper shoulders, and superior aspect of the upper back, a distribution that visually resembles the shape of a coat hanger. The primary muscular structures defining this region include the large, superficial trapezius muscle, particularly its upper fibers which extend from the occiput and cervical spinous processes to the clavicle and acromion. Deep to the trapezius lie other critical muscles, including the levator scapulae, splenius capitis, semispinalis capitis, and the suboccipital muscles, all of which contribute to head and neck posture and movement.
The trapezius muscle receives its primary motor supply from the spinal accessory nerve (cranial nerve XI). However, it also receives significant contributions from the ventral rami of the second, third, and fourth cervical nerves (C2-C4), which provide both motor and sensory fibers. The deeper muscles of the neck are innervated by the dorsal rami of the cervical spinal nerves.
The vascular supply to these muscles originates primarily from branches of the subclavian and vertebral arteries, placing them superior to the heart. This anatomical position makes these muscles particularly vulnerable to reductions in perfusion pressure
Pathophysiology
The pathophysiology of true coat hanger pain is intrinsically linked to disorders of autonomic regulation that result in orthostatic intolerance.
The hypoperfusion hypothesis is a prominent theory which states that there is inadequate blood flow to the tonically active anti-gravity postural muscles of the neck and shoulders (e.g. trapezius and splenius capitis) during gravitational stress. These anti-gravity muscles are in a constant state of partial contraction in the upright position requiring a robust oxygenated blood supply. With these muscles being located superior to the heart in the upright position, they are vulnerable to reductions in perfusion pressure.[1]
This leads to one theory in that the pain is ischaemic in nature. One study compared patients with multiple system atrophy (MSA) who have coat hanger pain with controls. They found that the muscle membranes in MSA patients become progressively depolarised with standing. There was no difference between MSA patients and controls in the supine position. The depolarisation is thought to be due to muscle ischaemia.[2]
Another theory is that the reduction in blood flow results in a reduction in muscle tone, neck flexion, and subsequent non-physiological stretching of cervical musculoskeletal structures such as the facet joints and ligaments which are richly innervated with nociceptors.[3]
Associated Conditions
Primary neurodegenerative disorders characterised by autonomic failure have a remarkably high prevalence of coat hanger pain. These include Multiple system atrophy (MSA) and pure autonomic failure (PAF) which are synucleinopathies that cause profound neurogenic orthostatic hypotension due to the degeneration of central and peripheral sympathetic pathways.[3]
One landmark study reported neck pain in 93% of patients with PAF and 51% of patients with MSA. The authors noted that the frequency of neck pain was directly related to the severity of the orthostatic hypotension; patients with PAF, who typically experience a greater postural blood pressure fall than those with MSA, also had a significantly higher frequency of coat hanger pain.[4]
Spinal cord injury, especially at the cervical or high thoracic levels, disrupts the descending sympathetic pathways necessary for peripheral vasoconstriction, frequently resulting in severe neurogenic OH. Studies in this population have documented a high prevalence of both OH (57.1%) and coat hanger neck pain (53.6%). The association is statistically significant, with 75% of SCI subjects with OH reporting the characteristic neck pain, compared to only 25% of those without OH.[1]
Parkinson's disease can lead to autonomic failure and neurogenic orthostatic hypotension, triggering pain via the hypoperfusion pathway.[5] Simultaneously, the cardinal motor symptoms of Parkinson's disease, such as rigidity and postural instability, can cause direct mechanical strain, spasm, and pain in the cervical and paraspinal musculature.
A wide range of conditions can cause pain in the coat hanger region (e.g. fibromyalgia), but would be less likely to be relieved rapidly by lying down.
Finally there is an association with orthostatic headache, which is defined as a headache that worsens within 15 minutes after sitting or standing and improves within 15 minutes of recumbency. This is syndrome has a large number of potential causes outside of the classic intracranial hypotension.[3]
Clinical Features
While many conditions can cause pain in the coat hanger region, the term "coat hanger pain" in its strictest clinical sense refers to a specific syndrome strongly associated with autonomic nervous system dysfunction.
The cardinal feature of true coat hanger pain is that it is provoked or significantly worsened by assuming an upright posture, such as standing or prolonged sitting, and is characteristically and often rapidly relieved by recumbency (lying flat). This postural dependency is the key distinguishing characteristic from other causes of pain in the same region.
The pain may induced by other factors that exacerbate OH such as morning timing (reduced blood volume from nocturnal diuresis), food (from splanchnic vasodilation) and warm environment (from cutaneous vasodilation).[3]
Orthostatic hypotension, clinically defined as a sustained drop in systolic blood pressure of at least 20 mm Hg or diastolic blood pressure of 10 mm Hg within three minutes of standing. There is a positive correlation between the magnitude of blood pressure drop and intensity of neck pain.[1]
Treatment
If the patient fits the classic clinical syndrome of coat hanger region pain that is relieved by recumbency and there is evidence of orthostatic hypotension, then a test of treatment for the orthostatic hypotension should be considered.
References
- ā 1.0 1.1 1.2 Cariga, P; Ahmed, S; Mathias, Cj; Gardner, Bp (2002-02). "The prevalence and association of neck (coat-hanger) pain and orthostatic (postural) hypotension in human spinal cord injury". Spinal Cord (in English). 40 (2): 77ā82. doi:10.1038/sj.sc.3101259. ISSN 1362-4393. Check date values in:
|date=(help) - ā Humm, A. M.; Bostock, H.; Troller, R.; Z'Graggen, W. J. (2011-12-01). "Muscle ischaemia in patients with orthostatic hypotension assessed by velocity recovery cycles". Journal of Neurology, Neurosurgery & Psychiatry (in English). 82 (12): 1394ā1398. doi:10.1136/jnnp-2011-300444. ISSN 0022-3050.
- ā 3.0 3.1 3.2 3.3 Khurana, Ramesh K (2012-07). "Coat-hanger ache in orthostatic hypotension". Cephalalgia (in English). 32 (10): 731ā737. doi:10.1177/0333102412449932. ISSN 0333-1024. Check date values in:
|date=(help) - ā Bleasdale-Barr, K M; Mathias, C J (1998-07). "Neck and other muscle pains in autonomic failure: their association with orthostatic hypotension". Journal of the Royal Society of Medicine (in English). 91 (7): 355ā359. doi:10.1177/014107689809100704. ISSN 0141-0768. Check date values in:
|date=(help) - ā Lei, Lucy Y.; Chew, Derek S.; Raj, Satish R. (2020-11). "Differential diagnosis of orthostatic hypotension". Autonomic Neuroscience (in English). 228: 102713. doi:10.1016/j.autneu.2020.102713. Check date values in:
|date=(help)
