The modern affliction of neck and shoulder pain with associated neurological symptoms into the upper or lower limbs is an all too common event following road traffic accidents. In previous generations and in other contemporary societies, whiplash injuries are almost unheard of indicating a significant psychological element to the declared pain, which is perhaps underpinned by the atmosphere of litigation.
Nevertheless within the neurosurgical world the symptoms caused by rapid forward flexion followed by posterior extension of the heavy human head on the slender cervical spine can cause damage to of muscle and ligamentous tissue; joint surfaces and even neurological elements of the cervical spine. It is unheard of for a whiplash injury to require neurosurgical attention in the form of surgery, but it is possible for symptoms of cervical spondylotic radiculopathy or indeed myelopathy to become manifest as a result of the energy imparted with the whiplash injury and even for a mild central cord syndrome to develop. In this chapter I shall discuss the pathophysiology of the whiplash injury; the symptoms and clinical signs; the diagnostic pitfalls and appropriate management for this difficult patient group from the neurosurgical perspective.
The human cervical spine has seven cervical vertebrae. These are relatively slender vertebrae, with no attached ribs, that classically have a bifid spinous process and a foramen in the transverse process. It is of note that almost all mammals have seven cervical vertebrae, only sloth’s and manatee’s are exceptions to this rule.
The two-toed sloth (Choloepus) have five to seven neck vertebrae while three-toed sloths (Paradypus) have eight or nine. The variation in cervical vertebrae coexists with rudimentary ribs in the long necked sloth, but complete ribs, fused to the sternum, in the short necked, which would appear to be linked to genetic changes (homeotic alteration). It is perhaps the slow lifestyle and low metabolic rate of these animals that has allowed evolution to alter the neck lengths without side effects such as thoracic outlet syndrome, still birth and cancer, which are commonplace if these variations occur in other mammals (Ref 1).
The evolution of the large Homo sapiens cranium protecting a heavy brain has posed a problem for the cervical spine, particularly as he has lived into middle and often old age. The wear and tear of the joints in the neck is commonplace as reflected in the covert incidence of cervical spondylosis (100% Ref.2).
Most natural flexion and extension, and forced flexion and extension, of the human neck is going to take place through the articulations of the disc and facet joints between C5/6 and C67. The articulations at the top of the neck, particularly between C1 and C2 (atlanto-axial) are mainly organised for rotation (Ref 3). All the segments from C3/4 down to C6/7 can move up to 15º in the sagittal plane. Lateral bending is performed by the lower cervical spine, but equal contribution to rotation occurs in the upper cervical spine to the lower cervical spine (70º each)
This is a traumatic event to the soft tissue structures in the region of the cervical spine including cervical muscles, ligaments, intervertebral discs and facet joints. This often happens due to hyperflexion (i.e. bending forwards) or hyperextension (bending backwards) or possibly rotational injury to the neck. In the absence of fractures, dislocations or intervertebral disc herniation it is the most common and non-fatal automobile injury. ( Reference 4&5). Symptoms may start immediately but more commonly are delayed several hours or days.
Whiplash has been graded from 0 to 4 (Michael Boynes):
0 – no complaints and no signs (not whiplash)
1 – neck pain or stiffness or tenderness but no signs (whiplash)
2 – the above symptoms with reduced range of motion or point tenderness (whiplash)
3 – the above symptoms with weakness, sensory deficit or absent deep tendon reflexes (whiplash).
4 – the above symptoms with fracture or dislocation (not whiplash).
Xrays and MR scans are required to confirm the diagnosis and exclude a fractured or herniated disc. In the absence of structural injury a “whiplash syndrome” will be diadnosed but there may well be pre-existing degenerative changes that may amplify and prolong symptoms.
Most treatments are symptomatic with topical applications, massage, physiotherapy and osteopathy.
There is no cure for whiplash but time usually heals.
In a study of 117 patients less than 56 years of age having whiplash injury due to automobile accidents (Switzerland Reference 6) recovery rate was as follows: –
3 months 56%
6 months 70%
12 months 76%
24 months 82% months
Only ¼ of the patients with symptoms at 2 years were restricted with regards to work. (¼ relates to 5 patients).
1. Irma Varela-Lasheras et al. Breaking evolutionary and pleiotropic constraints in mammals. On sloths, manatees and homeotic mutations. EvoDevo, 2011 in press.
2. FA Jenkins Jnr. Evolutionary development of the dens of the mammalian axis. Anatomical records 164:173-184 1969.
3. L.Penning. Whiplash. American Journal of Roentgenology, 130:317 to 326 1978
4. Hirsch S A, Hirsch P J, Hiramoto H, et al.: Whiplash syndrome: Fact or fiction? Orthop Clin North Am 19: 791-5, 1988
5. Riley L H, Long D, Riley Jr. L H: The science of whiplash, Medicine (Baltimore) 74:298-9,1995.
6. Radanov B P, Sturzenegger M, Di Stefano G: long-term outcome after whiplash injury. Medicine (Baltimore) 74: 281-97, 1995.