How To Address Ganglionic Cysts In The Tarsal Tunnel
Tarsal tunnel syndrome is an entrapment of the posterior tibial nerve or its branches within the tarsal tunnel.1 This syndrome is most frequently unilateral as opposed to carpal tunnel syndrome in the upper extremity, which is typically bilateral.2 Keck and Lam first described the term “tarsal tunnel syndrome” in 1962.3,4
Malaisé first described the clinical signs and symptoms of tarsal tunnel syndrome in 1918. Some of the symptoms include numbness or tingling in the soles of the feet and toes or a burning pain in the ankles.5 A sensation of tightness, cramping pain and worsening of symptoms with prolonged standing have all been associated with tarsal tunnel syndrome.6
Diagnosing this syndrome can be difficult as the symptoms of nerve compression are described in a vague way and may mimic other pathologies of the foot and ankle. Often the patient’s own misconception of his or her multiple foot problems adds to the difficulty.7 Adjunctive methods often aid in both diagnosing the syndrome and differentiating the etiology.
When it comes to proper treatment, the etiology of tarsal tunnel syndrome is just as important as making the correct diagnosis. Using both nerve conduction velocity (NCV) testing and visualizing the area with either ultrasonography or magnetic resonance imaging (MRI) can be key in the physician’s ability to apply the appropriate treatment plan. Magnetic resonance imaging clearly depicts bones, soft tissue and boundaries of the tarsal tunnel, and can often reveal the specific pathology responsible for tarsal tunnel syndrome. This modality easily shows lesions of the synovial sheath, varicose veins and ganglions, which may all present in the tarsal tunnel and can cause the syndrome.1
What You Should Know About Space-Occupying Lesions And Entrapment Neuropathies
One of the most frequently diagnosed neuropathies is related to the entrapment of the posterior tibial nerve and its branches within the tarsal tunnel. The symptoms of tarsal tunnel syndrome may be due to a number of local factors such as space–occupying lesions, trauma and systemic diseases. However, a large number of tarsal tunnel cases are idiopathic.
This article presents two case studies with both patients suffering with tarsal tunnel syndrome due to a ganglion, one originating from the flexor hallucis longus tendon and the other originating from the middle facet of the subtalar joint. Both cases presented with acute onset of unilateral neuropathy and pain.
In the following two case studies, ganglion cysts are the etiology of the patients’ symptoms. Stedman’s Medical Dictionary (27th edition) defines a ganglion as “a cyst containing mucopolysaccharide-rich fluid within a fibrous tissue, muscle, bone or a semilunar cartilage.” The ganglions usually originate “from a tendon sheath in the hand, wrist, foot or can be connected with the underlying joint.”
Conservative measures may not be the best options for managing and treating tarsal tunnel syndrome when it is caused by a space-occupying lesion such as a ganglion cyst. The use of strapping, orthotics or removable walking boots often fails because these modalities do not address the etiology, and the ganglion remains within the tarsal tunnel.
While one may consider many techniques, the basic purpose of tarsal tunnel surgery is to release the flexor retinaculum and dissect the fibro-osseous tunnel that makes up the tarsal tunnel. The specific structures one would release are the fascia envelopes of the abductor hallucis muscle, tibial nerve, medial and lateral plantar branches and the calcaneal branch.
The degree of dissection depends on the anatomical makeup of the individual and the degree of entrapment. When it comes to any space-occupying lesion you find in the exploration of the tarsal tunnel (a ganglion in our case), you would dissect and remove it with care so as to not damage normal structures of the area.
When a space-occupying lesion is involved with tarsal tunnel syndrome, surgery may be the only option to decrease pain and halt or reverse nerve damage. Although surgical release is not effective in all cases, Gondring, et al., found complete relief of symptoms in 85 percent of 68 feet in their study in 2003.5