Changes

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|Spinal cord

|Spinal cord

|*Ataxia, paresis or spasticity of one or more limbs, often asymmetrical, signs usually worse in hindlimbs, may see stumbling, falling, knuckling, toe dragging, circumduction, crossing over, tetraparesis - areflexia, hyporeflexia (LMN) or hyperreflexia (UMN) depending on site of lesion

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*Ataxia, paresis or spasticity of one or more limbs, often asymmetrical, signs usually worse in hindlimbs, may see stumbling, falling, knuckling, toe dragging, circumduction, crossing over, tetraparesis - areflexia, hyporeflexia (LMN) or hyperreflexia (UMN) depending on site of lesion

*Loss of reflexes or cutaneous anaesthesia

*Loss of reflexes or cutaneous anaesthesia

*Apparent lameness, particularly atypical or slight gait asymmetry of hindlimbs (not alleviated by local anaesthesia)

*Apparent lameness, particularly atypical or slight gait asymmetry of hindlimbs (not alleviated by local anaesthesia)

*Sacrococcygeal involvement will produce signs that mimic ''polyneuritis equi''  

*Sacrococcygeal involvement will produce signs that mimic ''polyneuritis equi''  

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|Peripheral nerves(may lead to injuries to muscle tendons or ligaments)  

|Peripheral nerves (may lead to injuries to muscle tendons or ligaments)  

|*Upward fixation of the patella

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*Upward fixation of the patella

*Exertional rhabdomyolysis

*Exertional rhabdomyolysis

*Back pain

*Back pain

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|Brainstem (cranial nerve signs, <5% cases)

|Brainstem (cranial nerve signs, <5% cases)

|*Atrophy of ''temporalis'' and ''masseter'' muscles, loss of facial sensation (V)

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*Atrophy of ''temporalis'' and ''masseter'' muscles, loss of facial sensation (V)

*Facial (VII) and vestibulocochlear (VIII) nerve deficits often seen together:  

*Facial (VII) and vestibulocochlear (VIII) nerve deficits often seen together:  

**VIII - vestibular signs: nystagmus, head tilt, base-wide stance (peripheral or central vestibular disease)

**VIII - vestibular signs: nystagmus, head tilt, base-wide stance (peripheral or central vestibular disease)

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|Cerebrum, basal nuclei, cerebellum:

|Cerebrum, basal nuclei, cerebellum:

|*Abnormal menace response

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*Abnormal menace response

*Circling

*Circling

*Seizures (may be the only clinical sign)(82 in Furr)

*Seizures (may be the only clinical sign)(82 in Furr)

*Altered behavior  

*Altered behavior  

*Depression

*Depression

*Narcolepsy-like syndrome  

*Narcolepsy-like syndrome

Lesions of the brainstem, cerebrum or cerebellum are less frequently recognized than those of the spinal cord.  Horse with severe EPM may be unable to stand or swallow and, if left untreated, progress to recumbency within 14 days to 6 months. (Pasq) This deterioration may occur smoothly or spasmodically (Merck) but is likely to result in death.  It has been suggested that rapidly progressive presentations reflect brainstem lesions.(Furr)  

Lesions of the brainstem, cerebrum or cerebellum are less frequently recognized than those of the spinal cord.  Horse with severe EPM may be unable to stand or swallow and, if left untreated, progress to recumbency within 14 days to 6 months. (Pasq) This deterioration may occur smoothly or spasmodically (Merck) but is likely to result in death.  It has been suggested that rapidly progressive presentations reflect brainstem lesions.(Furr)