Tetraparesis: Spinal cord diseases

By | September 2, 2013

Spinal cord diseases that can cause tetraparesis are listed in Spinal cord diseases that can cause tetraparesis.

Spinal cord diseases that can cause tetraparesis.

Mechanism of disease Specific diseases
Degenerative Inherited neurodegenerative diseases
Calcinosis circumscripta []
Cervical stenotic myelopathy (Wobbler syndrome) []
Degenerative myelopathy []
Intervertebral disc disease (Hansen type I and 11) []
Spinal synovial cysts []
Anomalous Atlantoaxial instability []
Dermoid sinus []
Osteochondromatosis []
Syringohydromyelia []
Vertebral and spinal cord anomalies []
Neoplastic Extradural: metastasis; vertebral tumours (sarcomas, plasma cell tumours); lymphoma []
Intradural-extramedullary: meningiomas; nerve sheath tumours; metastasis []
Intramedullary: ependymomas; gliomas; metastasis; round cell tumours []
Inflammatory Discospondylitis / osteomyelitis / physitis []
Empyema[]
Granulomatous meningoencephalomyelitis []
Infectious meningoencephalomyelitis []
Steroid-responsive meningitis — arteritis []
Idiopathic Arachnoid cysts []
Toxic Tetanus []
Trauma Vertebral fractures / luxations []
Epidural haemorrhage []
Spinal cord contusion []
Traumatic disc herniation []
Vascular Fibrocartilaginous embolism []
Spinal cord / epidural haemorrhage []
Thromboembolic disease []

Tetraparesis: Degenerative diseases

Tetraparesis: Anomalous diseases

Neoplastic diseases

Neoplasia can cause pain and tetra- or paraparesis, depending on the location of the lesion. In dogs, extradural tumours (e.g. primary or metastatic sarcomas, metastatic carcinomas and phaeochromocytomas, and round cell tumours) account for approximately 50-60% of spinal tumours, intradural tumours (meningiomas and nerve sheath tumours) account for approximately 30% and intramedullary tumours (e.g. gliomas and ependymomas) account for approximately 10% (). In cats, the most common spinal tumour is lymphoma. Spinal lymphoma is usually extradural and more likely to occur in the thoracolumbar spine, but can occur in the cervical spine and may infiltrate the brachial plexus (). Neoplasia is more likely to affect older animals and can produce signs by direct compression of the spinal cord, infiltration and destruction of the spinal cord parenchyma, intraparenchymal haemorrhage or by inducing pathological vertebral fractures. Diagnosis, treatment and prognosis of neoplasia affecting the vertebrae and spinal cord are addressed in detail in site.

Nutritional diseases

Hypervitaminosis A

This disease, also known as deforming cervical spondylosis, affects cats that are fed a pure liver diet and is therefore extremely rare in these days of manufactured diets ().

Inflammatory diseases

Discospondylitis

Infection of the intervertebral disc and adjacent vertebral endplates by bacterial or fungal organisms is a common cause of spinal hyperaesthesia in dogs (cats are rarely affected). If left untreated, spinal cord dysfunction can occur as a result of either local inflammation, compression from herniated infected disc material or local abscess formation, or pathological vertebral fracture. Discospondylitis can affect any site in the spine and caudal cervical lesions are common. Because the most common presenting sign is spinal hyperaesthesia, diagnosis, treatment and prognosis of discospondylitis are covered in site.

Spinal empyema

Epidural empyema is a rare but important cause of spinal cord disease. Local bacterial infection of the epidural fat results in accumulation of purulent material causing compression and inflammation of the adjacent spinal cord. This can be a result of local extension of infection from discospondylitis or a cat bite abscess, or can result from haematogenous spread. In humans, it is also reported as a complication of spinal surgery and epidural catheter placement. Characteristic signs are a high fever, acute progressive spinal hyperaesthesia and progressive myelopathy, with the neurological deficits reflecting the site of infection. The diagnosis and treatment of this disease are described in site.

Meningoencephalomyelitis

Inflammatory conditions of the meninges and the central nervous system can cause tetraparesis as a result of involvement of the brainstem or the spinal cord. Typically signs are multifocal, but any inflammatory or infectious CNS disease can cause focal signs of spinal cord disease. Examples of infectious or inflammatory diseases of the CNS that can cause focal signs of spinal cord disease include FIP, canine distemper, fungal infections (in particular Cryptococcus neoformans), the protozoal infections Neospora caninum and Toxoplasma gondii, rickettsial infections and granulomatous meningoencephalomyelitis (GME). These diseases are diagnosed by analysis of cerebrospinal fluid in combination with appropriate titres.

Steroid-responsive meningitis-arteritis (SRMA)

The predominant manifestation of SRMA is severe spinal hyperaesthesia and this disease is therefore described in full in site. With chronic severe disease, neurological deficits (ataxia, para-or tetraparesis) can be present as a result of concurrent myelitis, but this is unusual ().

Idiopathic diseases

Arachnoid cysts

Arachnoid cysts are focal accumulations of cerebrospinal fluid within the subarachnoid space. The term cyst is somewhat misleading, as frequently cyst walls are not evident. Accumulation of cerebrospinal fluid over time causes progressive compression of the spinal cord and neurological deficits related to the site of compression.

Clinical signs: Arachnoid cysts occur most commonly in young large dog breeds (e.g. Rottweiler) dorsal to the cranial cervical spinal cord, and in older smaller breeds (e.g. Pug) dorsal to the thoracolumbar spinal cord (), though cysts can occur at any site, at any age and in any breed of dog. Onset of signs (tetraparesis, paraparesis, ataxia) is typically chronic and it is notable that dogs can present with faecal or urinary incontinence as an early sign (). Neck pain may be present.

Pathogenesis: The aetiology of these cysts is most likely multifactorial with inherited predisposition, trauma and arachnoiditis all postulated to play a role ().

Diagnosis: Survey radiographs are unremarkable. Cysts are identified as a focal accumulation of contrast medium in the subarachnoid space, or an intradural filling defect on myelography (). They are also visible as an accumulation of fluid in the subarachnoid space on MR images.

Treatment and prognosis: Recommended treatment in dogs with neurological deficits is surgical decompression by removal orfenestration and marsupialization of cysts. Conservative management may improve a small proportion of dogs but is only recommended in animals with mild neurological deficits. Conservative management includes controlled exercise and anti-inflammatory doses of prednisolone. Animals should be monitored regularly and surgery recommended if deterioration occurs.

The prognosis for dogs treated surgically depends on the severity and duration of clinical signs and the age of the dog. Young dogs with mild signs have an excellent short-term prognosis (< 1 year). Signs may recur in approximately one-third of dogs in the longer term ().

Tetraparesis: Toxic diseases

Tetraparesis: Traumatic diseases

Tetraparesis: Vascular diseases

Degenerative diseases: Breed-specific neuropathy

Metabolic diseases

Endocrine neuropathy

Endocrine diseases that are known or suspected to cause a peripheral neuropathy include diabetes mellitus, hypoglycaemia (as a result of insulinoma in dogs), hypothyroidism and hyperadrenocorticism.

Diabetes mellitus: Poorly controlled diabetes mellitus causes distal axonal degeneration, with the longest peripheral nerves affected first. The most common manifestation of this problem is a sciatic neuropathy in cats causing a plantigrade stance in the pelvic limbs at rest and when walking (). Affected cats retain the ability to walk but hock flexion is absent when the withdrawal reflex is tested. Although pathological changes and sporadic cases of neuropathy have been detected in diabetic dogs, it is usually a sub-clinical problem in this species. Diagnosis is strongly suspected in animals with poorly controlled diabetes and classic neurological findings. Definitive diagnosis is made by electrophysiological studies and nerve biopsy. Although axonal degeneration can be present in severely affected animals, the most common finding is abnormalities in Schwann cells and myelin (). Prognosis for full recovery of peripheral nerve function is guarded, but restoring normoglycaemia prevents progression and in mild cases may result in complete resolution of neurological signs ().

Hypothyroidism: This can be associated with generalized weakness as a result of a peripheral neuropathy. In addition, idiopathic neuropathies such as facial or laryngeal paralysis, peripheral vestibular syndrome and megaoesophagus have been linked to hypothyroidism but the exact relationship between these neuropathies and hypothyroidism remains unclear (). Diagnosis of hypothyroidism is made by measurement of serum total and free T4 and TSH levels. Supplementation with thyroxine may reverse signs of generalized peripheral neuropathy over 2-3 months but laryngeal and oesophageal abnormalities usually persist.

Hyperadrenocorticism: A peripheral neuropathy has been reported in dogs with hyperadrenocorticism but is a rare complication of this disease and is more commonly a subclinical disorder.

Neoplastic diseases

Insulinoma

Chronic, severe hypoglycaemia (< 3 mmol / l) is almost invariably associated with insulinomas in dogs. The most common neurological signs result from the effects of hypoglycaemia on the CNS (seizures, weakness, exercise intolerance and collapse). Persistent hypoglycaemia may also cause a distal peripheral neuropathy that manifests initially as a stiff gait, particularly in the pelvic limbs, but progresses to more obvious signs of a generalized peripheral neuropathy with prominent sciatic deficits (). This paraneoplastic neuropathy has also been identified in ferrets with insulinomas. Treatment of the insulinoma may improve the gait, depending on the extent of the underlying disease.

Paraneoplastic neuropathy

Paraneoplastic peripheral neuropathies are well recognized in humans in association with particular types of cancer but infrequently recognized in dogs and cats. With the exception of the neuropathy associated with insulinomas in dogs (see below), there are only sporadic reports of neuropathies associated with a variety of different cancers such as bronchogenic and mammary carcinoma and multiple myeloma (). Treatment of the primary neoplasia may result in an improvement in signs due to the neuropathy ().

Idiopathic diseases

Distal denervating disease

This is reportedly a common peripheral neuropathy in the UK but it has not been recognized elsewhere. The aetiology of this disease is unknown but, as the name implies, the terminal and intramuscular branches of motor nerves degenerate, producing progressive tetraparesis that is first evident in the pelvic limbs (). Weakness progresses over days to weeks to LMN tetraplegia and dysphonia, and severe muscle atrophy develops. Diagnosis is by electrophysiological studies (EMG shows that denervation and nerve conduction studies are abnormal). Biopsies are not helpful except to rule out other diseases, as the lesion is usually distal to the biopsy site. Treatment involves supportive care and the prognosis is excellent if adequate nursing care can be given-inflammatory diseases.

Tetraparesis: Inflammatory diseases

Tetraparesis: Toxic diseases

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