Patients with hydatid disease usually present with symptoms caused by spinal cord or nerve root compression (Akhan et al. 1991; Pandey and Chaudhari 1997; Işlekel et al. 1998; Hilmani et al. 2004; Layadi et al. 2005; Adilay et al. 2007; Gopal et al. 2007; Kaen et al. 2009; Limaiem et al. 2010). Hydatid disease can be seen at any level of the spine (Bouras et al. 1984; Mathuriya et al. 1985; Göçer et al. 1994; von Sinner and Akhtar 1994; Pandey and Chaudhari 1997; Turgut 1997; Singh et al. 1998; Layadi et al. 2005; Adilay et al. 2007; Song et al. 2007; Arif and Zaheer 2009; Senoglu et al. 2009), but thoracic vertebrae are more commonly involved (Polat et al. 2003; Gopal et al. 2007), sometimes misleading to the diagnosis of Pott’s disease (Bouras et al. 1984; Turgut 1997; Song et al. 2007) and mimicking tuberculous spondylodiscitis (Tabak et al. 2007). Intradural hydatid at the foramen magnum was reported with all features of spinomedullary compression including respiratory distress, so hydatid disease should be considered in the differential diagnosis of compressive lesions at the foramen magnum (Mathuriya et al. 1985).

Hydatid cysts were classified according to their relationship with the dura mater, spinal canal, and spinal cord (Pamir et al. 1984; Fahl et al. 1994; von Sinner and Akhtar 1994; Berk et al. 1998; Turgut 2002; Polat et al. 2003; Adilay et al. 2007; Gopal et al. 2007; Arif and Zaheer 2009; Güneş et al. 2009) as intramedullary hydatid cysts, intradural extramedullary hydatid cysts, extradural-intraspinal hydatid cysts (Fig. 12.2), hydatid cysts of the vertebrae (Figs. 12.3, 12.4, 12.5, 12.6, and 12.7), and paravertebral hydatid cysts (Figs. 12.4, 12.8 and 12.9) (Polat et al. 2003). Intradural hydatid cysts are rare (Pamir et al. 1984; Kahilogullari et al. 2005; Arif and Zaheer 2009; Güneş et al. 2009).

Lack of osteoporosis and sclerosis in involved bone, absence of damage to intervertebral disk spaces and vertebral bodies, paraspinal extension, and (in the thoracic spine) involvement of contiguous rib are the most common features of spinal hydatid disease (Polat et al. 2003). Hydatid disease of the spine usually begins in the vertebral body. The cysts show slow growth in the direction of least resistance (Polat et al. 2003; Phatak 2006). With time, the parasite replaces the osseous tissue and destroys the cortex. It then spreads from bone to surrounding tissue such as muscle and the spinal cord (Polat et al. 2003). Extension into the spinal canal results in spinal cord and neural compression (Gopal et al. 2007). Hydatid cysts that lack the typical radiographic appearance may be mistaken for arachnoid cysts (Secer et al. 2008).

Plain X-rays are routinely obtained as a part of initial imaging but radiographic findings of spinal hydatid disease are nonspecific (Fig. 12.3). Plain X-rays may show bone destruction (Fig. 12.4) and sometimes abnormal soft tissue masses in the paravertebral region (Phatak 2006). However, they may show no bony abnormalities (Gopal et al. 2007; Arif and Zaheer 2009). It should be remembered that, radiographically, no sclerosis or periosteal reaction is evident in the early stages of the disease (Farzan et al. 2006).

Computed tomography (CT) and magnetic resonance imaging (MRI) demonstrate cystic cerebral hydatid disease effectively (Bükte et al. 2004) and they also serve for imaging of spinal hydatid disease (Figs. 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, and 12.9). After obtaining plain X-rays, CT and MRI should be used for further imaging as diagnostic tools of choice (Göçer et al. 1994; Turgut 1997; Gopal et al. 2007). CT and/or MRI techniques were found to be extremely useful, both for reaching the correct diagnosis and for proper surgical management of hydatid disease (Turgut 2002). CT and MRI have revolutionized neurosurgical practice for the diagnosis of hydatid cysts and allowed early diagnosis of the disease and provided localization of the lesions more accurately than we could do with plain X-ray, and also they could show multiple lesions (Turgut 1997); therefore, they are of value in preoperative planning of the surgical approach to hydatid lesions of the skeleton.

On CT and MRI, the appearance of the cystic fluid resembles that of cerebrospinal fluid (CSF) (Figs. 12.2, 12.3, 12.8, and 12.9) (Polat et al. 2003; Layadi et al. 2005; Gopal et al. 2007; Senoglu et al. 2009). In the past, myelography and CT myelography were used in the diagnosis of spinal hydatid disease (Işlekel et al. 1998), but now MRI has replaced the need for invasive myelography procedures.