Tethered spinal cord: a rare cause of foot deformities

Excerpt

A 22-year-old man was presented with gait instability developed over the last 6 months, accompanying by painful distal dysesthesias in the legs and neurogenic bladder. He reported a 10-year history of progressive intrinsic foot muscle weakness and atrophy bilaterally, which was arbitrary attributed to Charcot–Marie–Tooth hereditary neuropathy, despite the absence of similar deformities in close family members, because this type of neuropathy is the commonest cause of such foot morphology in the region of the patient’s geographic origin. Neurologic examination showed normal motor and sensory function in the upper limbs, asymmetric, more on the right, distal leg muscle weakness (MRC score right gastrocnemius 1/5, left gastrocnemius 2/5; right and left tibialis anterior 4/5; right abductor hallucis 0/5, left abductor hallucis 2/5) (Figs. 1, 2), suppressed tendon reflexes in the legs and hypoesthesia in the anterior and lateral aspects of right leg. The patient needed 4–5 intermittent self-catheterizations per day. Initially, neuropathy was excluded by the normal motor and sensory nerve conduction findings except for the absent response from right abductor hallucis muscle. Consecutively, the existence of several café-au-lait spots on the patient’s back, lower abdomen and thighs in association with family history of neurofibromatosis type Ι raised the suspicion of neurogenic tumor originated from the lumbosacral roots. MRI of the lower spine revealed a tethered spinal cord (Fig. 3), setting the correct diagnosis after many years delay from the first appearance of clinical symptoms in childhood. Inspection of lumbosacral area did not reveal midline cutaneous stigmata such as localized hypertrichosis, dermal sinus or dimple, which would have led to an early investigation for occult spinal dysraphism [1]. Surgical release of spine cord traction by sectioning the tight filum terminale stabilized the patient’s manifestations, including improvement of bladder function. Tethered cord syndrome is a well-described entity manifested during childhood or adolescent with predominately neurological symptoms and signs in the lower limbs [2]. Pain in the back and legs is the commonest sensory symptom, whereas foot muscles atrophy prior to skeletal maturation is also a frequent feature resulting in pes cavus and claw toes, which could be misinterpreted as characteristics of hereditary peripheral neuropathy. In cases such as the presenting one, low-lying of conus medullar without overt congenital stigma could go on unnoticed from childhood to adulthood minimizing the possibility of recovery after surgical intervention [3]. The progressive nature of this condition became apparent in our patient when the clinical picture supplemented with micturition deficit that pointed to a sacral cord lesion. A previous review study showed that surgical untethering offers a good chance to restore bladder function even when performing in adults [4]. It is suggested that tethered cord syndrome should be considered in differential diagnosis of foot deformity in young patients to prevent further neurological deterioration [5].

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